a market-town in the hundred of Sparkenhoe, in the county of Leicester, 107 miles from London. Near it is the celebrated field of the battle between Richard III. and Henry VII., then Duke of Richmond, by which the crown of England was transferred to the latter. The market is held on a Wednesday. The inhabitants amounted in 1801 to 791, in 1811 to 954, and in 1821 to 1117.

BOTAL or BOTALLI, LEONARD, physician to the duke of Alençon, and to Henry III., was born at Asti in Piedmont. He published several books in physic and surgery; and the best edition of his works is that of Leyden, in 1660, octavo, published by Van Hoorne.

1 Particularly in the Correspondence of the Baron de Grissin, and the Memoirs of Marmontel. Linnaeus divides all natural objects into three grand classes, which he calls kingdoms; and the sciences which treat of these are zoology, botany, and mineralogy. Botany, with which we are to be occupied in this place, enables us to distinguish, arrange, and name all plants or vegetables.

Some years ago, Baron Humboldt made a calculation as to the probable number of the different species of plants existing on the face of our globe. Of late, however, owing to the many novelties that have reached us from Brazil and the East Indies, it has been supposed that his estimate is much under the truth. At least sixty or seventy thousand, described or undescribed, are scattered through different collections, and every day brings to light additional species; so that at present the probable number of vegetable productions may not be too highly estimated at nearly a hundred thousand. To obtain a knowledge of every one of these individually, and without relation to any other, would be a Herculean task, for which the utmost extension of human life might not be sufficient, and which, though procured, could not be imparted to others. The study would thus be selfish, and the labours of a lifetime useless. Valuable medical properties might be observed in some one vegetable; but posterity would, in all probability, find similar properties in another plant, much sooner than re-discover that formerly known. Thus many plants whose medical qualities were highly esteemed by our ancestors, are now entirely unknown to us as possessing such. To remedy these evils, means must be resorted to for the classifying or arranging of vegetables. If we divide them into trees, shrubs, herbaceous, biennial, and annual, we shall have five divisions; so that supposing an equal number to each, we shall have only to look into one of those sections for what we are in quest of. Again, each of these may be subdivided according to the height to which the plant grows, the colour of its flower, or its capability of bearing an esculent fruit. But this is one of the rudest systems, and, though used in the earliest state of the science, was soon found to be subject to great variation, and to want the necessary precision. Other more philosophical divisions were afterwards adopted, to which, and the steps requisite for the knowledge of them, we intend to devote this article.

The necessity of a classification being once admitted, resemblances between individuals, not before observed, could not long escape the attention. Thus the affinities inter se of the different species of pine, of the ash, of the lime, of the strawberry, or of the rose, must soon have been admitted; and in framing a system, care would be taken to place these by the side of the allied species, whether in appearance or in qualities. This is what is termed arranging plants according to their species. It would likewise be soon observed that small groups of these species had more affinity between themselves than with other groups;—a general idea would thus be attached to each of these, which would now form a genus;—and when these genera were placed one after the other according to some property or resemblance real or fancied, we should have the arrangement of plants by their genera. Whether, then, we proceed by making grand primary cuts or divisions among all the known vegetables, and then proceed to subdivide these until we arrive at genera and species; or commence by the grouping of species and genera, and mount upwards, we shall attain the means of more readily distinguishing and naming plants, and consequently of imparting to others the result of our observations on their properties and uses.

The cui bono in botany is a question that has often been asked by those who conceive that mere classification is the ultimate object of botany; but, from what has already been said, we trust it will be seen that classification is only the necessary consequence of a wish to impart our ideas to others. It is a universal language, without which the observations of one can be of no use to another, but by which the instructed can unfold to each other, at the remotest parts of the earth, what species or genera of plants have been discovered to possess remarkable properties. "The standing objection to botany," says the eloquent author of the *Natural History of Selborne*, "has always been, that it is a pursuit that amuses the fancy and exercises the memory, without improving the mind, or advancing any real knowledge; and where the science is carried no farther than a mere systematic classification, the charge is but too true. But the botanist who is desirous of wiping off this aspersion should be by no means content with a mere list of names; he should study plants philosophically,—should investigate the laws of vegetation,—should examine the powers and virtues of efficacious herbs,—should promote their cultivation, and graft the gardener, the planter, and the husbandman, on the phytologist: not that system is by any means to be thrown aside,—without system, the field of nature would be a pathless wilderness; but system should be subservient to, not the main object of, our pursuit." Nor ought an objection to be urged against the pursuit of those parts of botany from which hitherto no immediate use has been derived. From the highest organized plant to the lowest, all form a chain, in which a link lost or broken disconnects the whole, and to which the recent addition of new links, in the shape of new species, has tended much to the increase of our knowledge. What anatomist has not derived delight from the examination of the eye of a fly; and what botanist has not obtained information from the meanest weed! But it is even important to attend to the lowest class of vegetables. The lichens furnish many valuable dyes; the algae afford food or medicine; and we are all so alarmed at the poisonous effects of many fungi, that scarcely above two or three species are eaten in this country, whereas, if attention were paid to their botanical character, several far superior in flavour to the common mushrooms might be made use of with perfect safety.

The definition of botany here adopted, though easily understood and perfectly correct, is sometimes of little value to the practical man. Between mineralogy and the two other sciences of zoology and botany we believe there can be little confusion; but between zoology and botany, in the subjects belonging to both of which the living principle seems equally to exist, not only are there great points of resemblance, but instances occur in which it is nearly impossible for the eye to determine whether what we see belongs to the one or to the other kingdom.

The distinction made by Linnaeus between plants and animals consisted principally in the power of motion in the latter. Many animals have, however, now been discovered, which seem to be unable to remove themselves from the spot on which they first made their appearance; and, on the other hand, there are many plants, as the duckweed (*Lemna*), hall-conferva (*Confera aquagropila*), and others, which, if they have roots, do not send them into the earth, but float about as if in search of food; and our distinguished countryman Mr Brown, whose philosophical observations all must respect, has within these few years demonstrated that the component particles or molecules of all matter whatever, whether organized or not, when suspended in a fluid, and viewed with a suitable microscope, are found to be in motion without any visible agency. Perhaps the true differences are to be looked for in sensation and an intestinal canal in the animal kingdom, into which the food is collected; whilst plants are endowed only with irritability, and receive the food through many canals or mouths. But this, although it were universally acknowledged, is of little service, as confusion is only likely to arise in the case of the smallest and least organized, and where the correct knowledge of the anatomical structure is attended with almost insuperable difficulties. In many zoophytes, or lower tribes of marine animals, the external horny or calcareous covering so resembles a plant in its mode of ramification, as to cause doubts which are not easily removed; and there consequently exist many natural objects to this day that are claimed by both the zoologist and botanist. This similarity, combined with the motion to be observed in all molecules, has, we think, given rise to the singular delusion under which many celebrated men abroad have for some years past laboured, when they assert that the minute aquatic algae were animalcules in the first stages of their being, but which afterwards took root and became plants.

A rudimentary plant may have often been mistaken for an infusory animal, and may have even been described as such; and although there be no absolute practical character of almost any use to enable us to distinguish the two, yet we consider their identity as a mere matter of speculation, that has never been proved, and which is not borne out by any analogy derived from what are more organized, and on which observations would be less subject to error.

Subservient to the actual classification and determination of plants, and consequently forming branches of the science of botany, are, 1st, Organography, or the anatomy of plants, or the knowledge of the structure of their parts or organs; 2d, Physiology, or the knowledge of the functions of these parts; 3d, Pathology, or the derangements to which these functions are exposed; 4th, Terminology or Glossology, or the knowledge of the terms employed to designate the parts or organs; 5th, Phytography, or the art of describing plants, so that every species may be distinguished and recognised; and, lastly, Taxonomy, or the art of combining all these in such a way as to produce a systematic arrangement or classification.

What are usually called medical botany, agricultural botany, and economical botany, do not belong to the science of botany, as one might at first suppose from the names, but form respectively mere connecting links between botany and materia medica, as well as agriculture and domestic economy. They exhibit the relation existing between vegetables and the arts, and point out the uses to which different plants are applied. But although they therefore must fall under other subjects in this work, a certain knowledge of their general relation must be of considerable use to the botanist, inasmuch as it may enable him to frame a classification that will bring nearer together plants of similar properties and virtues, as well as of a similar form and structure.

In the same way, botanical geography is not a branch of botany. This exhibits the relation between vegetables and the soil on which they grow, and the climate in which they delight, or, in other words, the physical causes, and the laws of their distribution over the surface of our globe. This will form a part of Physical Geography.

Horticulture or gardening, or the art of cultivating plants so as to improve their beauty or ameliorate their qualities, is dependent on vegetable pathology; but it has long been considered as separate from botany, and will be treated of as a distinct science.

The above six branches of botany are so intimately connected, that it is difficult to discuss one without encroaching on the others. As, however, these are discussed in other parts of this work, we shall here confine ourselves, as much as the nature of the subject will admit, to the three latter,—Glossology, Phytography, and Taxonomy; under which last will be found a short historical sketch of the science.

I.—GLOSSOLOGY.

Glossology, or, as Linnaeus called it, Terminology, gives us, as has already been stated, the knowledge of the terms employed, or furnishes definitions of the names applied to the different parts or organs. The structure of these constitutes organography or anatomy. An account of the organs themselves belongs also, strictly speaking, to the same branch of the subject; but as a mere explanation of terms might prove useless and uninteresting, without understanding to what these terms are to be applied, we shall here exclude the elementary organs, or those which compose the others, and blend the two together; and thus, by explaining the organs and their successive developments, endeavour to lay a foundation, without which a knowledge of the natural system of classification cannot be acquired. Under Vegetable Anatomy, these organs are treated of as subservient to physiology. Here we shall consider them as connected with classification. And as in this article we do not intend to insert a catalogue or description of plants, so we shall pass over many terms that are not essential to a general view of the subject.

The organs of plants not elementary have been divided by De Candolle into the fundamental and reproductive. The former are such as are essential to the nutrition of the plant, while the latter are mere modifications of these. We shall therefore first proceed to the

FUNDAMENTAL ORGANS.

These consist of roots, stems, and leaves.

Roots (Radices).

We shall suppose a seed put into the ground under favourable circumstances. The inherent vital principle common to both plants and animals begins to operate; and a development takes place downwards as well as upwards. The descending portion is termed the Root; and by it plants are fixed to the earth, and nutriment absorbed. In some aquatic plants no root whatever is perceptible. But in such apparent aberrations from what seems a general rule of nature, it may be presumed by analogy that roots do exist even when they have not been observed; in confirmation of which it may be stated, that many plants to which roots were long denied, have actually possessed them in some parts of their existence, and are capable of deriving nourishment either from the earth, water, or air, although in a few the foliaceous portions of the plant are such as almost to preclude the necessity of their having any.

There are several characters which distinguish the root from the stem. The principal are the absence of leaves, of pith even in those plants in which it is abundant in the stem, and of spiral vessels.

A root usually consists of three parts: the neck (collum), or line of separation from the stem; the body or middle portion of the root; and the attenuated fibrous portion, or little roots through which the nourishment is principally derived. Keeping this in view, a root of the simplest kind is, 1st, what is termed conical, or the principal or tap root as it is sometimes called; this tapers downwards, emitting fibres from various parts of its surface, as in the carrot (Plate CXII. fig. 1): 2d, when the conical root is attenuated Glossology towards the neck, as well as below, it is called fusiform (fig. 2), as the radish: 3d, when swollen out extremely in the upper part, and suddenly attenuated below, it is napiform (fig. 3), as in the turnip: 4th, when the fusiform root is as it were cut off suddenly, it is termed abrupt (premorsus) (fig. 4), as in the devil's bit scabious: 5th, fibrous when the body of the root is so reduced as not to be apparent, and nothing is seen but simple or branched fibres proceeding from the neck: 6th, when these fibres swell out slightly in the middle, the root is called fasciculated (fig. 5): 7th, when the fibrous root bears, either at its neck, or here and there attached to its fibres, one or more tubers, fleshy, and containing much starchy feculent matter, it has been often called tuberous, but ought really to be termed tuberiferous, such tubers serving for the nourishment of the plant; when two of such tubers are placed together, as in some species of orchis, they are said to be didymous (fig. 6); and when these again are divided up to the middle into diverging lobes, they are didymous palmate (fig. 7). Some give the name of tuberous roots to any root whatever that contains swellings or tubercles on some part of its length; but in neither sense ought tubers to be classed among roots. In the one they are more properly short, fleshy, subterranean stems, containing usually eyes or buds, from which new plants arise; and in the other they have a very different structure, and are generally termed, 8th, grammatized roots. These exhibit a collection of small tubercles with eyes fit for the reproduction of the plant, without being enveloped by cellular tissue filled with starchy fecule, and thus differ essentially from the tuberiferous. In the same predicament with the tuberiferous is the bulbous root (fig. 8). This consists of a thin, flat tubercle, called by cultivators of hyacinths the crown, from the lower part of which proceeds a fibrous root, while above there is a bulb or peculiar kind of bud, formed of a number of scales (as in the lily), or coats (as in the onion), closely applied to each other; such may rather be termed bulbiferous roots, the bulb being equivalent to a leaf-bud, and the crown to a stem.

With regard to direction, there are only two requiring any notice. The one is contorted, when bent upwards and downwards in a zig-zag manner, as may be seen in the bistort; the other is a creeping root. The usual direction for a root is towards the centre of the earth, but it sometimes happens that one or all of its parts deviate at a right angle from this, and proceed laterally parallel to the surface. When this takes place it is said to be creeping. Roots of this kind are said to be among the greatest enemies the agriculturist has to encounter; but they are in a measure harmless, much confusion prevailing between them and subterranean branches; and we would therefore warn the young botanist not to fall into the error. Indeed the number of creeping roots is much less than has been generally thought; for in most cases these will be found to be true branches springing off from the stem above the neck of the root, but afterwards developed under ground, and even from different points throwing out radical fibres. Among these is the couchgrass (Triticum repens), and the potato, the fibrous parts of which bearing the tubers are now ascertained to be branches, as might indeed have been long ago suspected, from the care found necessary by cultivators to be paid to the heaping up of the earth on the lower part of the stem, so as to increase the number of these branches, and render the crop more abundant. In some plants, as in Vicia ampliflora, such branches or false roots bear pods under ground.

Stems (Caules).

Reverting to the germination of a seed, that part which springs upwards is the stem: it is therefore the intermediate body between the root and the leaves. When the Glossology first state of germination is observed, the rising stem is surrounded by rudimentary leaves. It is thus similar to Pl. CXII., those gems or leaf-buds that are afterwards observed in the axil of all leaves, and which afterwards become branches; and it may therefore be stated in general terms, that all stems are produced by the successive developments of leaf-buds.

When the stem of a plant arising from a seed is evident, the plant is termed caulescent; and when not apparent, or scarcely so, the plants have received the names of acuales or subacuales. These last terms, however, must not be taken in a rigorous sense; for although a stem be sometimes extremely short, or even entirely under ground, it always exists. We may refer here to Gentiana acuulis, Carduus acuulis, and many others, said to have no stem, but which really have one so surrounded by the bases of the leaves, as to be overlooked until they be planted in a more genial soil, when the stem becomes more visible. We have already stated that the crown of what is called a bulbous root is the real stem;—and in the genus Cyclamen, what is usually considered a tuber is an actual stem, from the base of which fibrous roots are protruded, and from the top, leaves and flowers.

It often happens that the stem, instead of ascending, stretches, either wholly or in part, under ground or on the surface, emitting here and there roots from below, and branches or leaves which rise upwards. Such a stem is called a rhizoma (fig. 9), or, if it do not emit fibres, a cornua. Most of what Linnæus improperly described as creeping roots are of the former description: of these each rising branch may easily be separated, and becomes a new individual. The jointed roots or scaly roots of botanists are also subterranean stems; for the knots and scales are the rudiments of buds and leaves, which no true root possesses. Sometimes a plant pushes out horizontally long stems of a peculiar nature, emitting only from the extremity roots and leaf-buds, as in the strawberry. Such stems are termed stolones or runners.

Branches as well as stems arise from leaf-buds. Every leaf or modification of a leaf possesses these in their axil, or the angle formed by the leaf and the branch; and therefore all leafy stems must likewise be branched, and without any limit to the ramification, unless the leaf-bud has met with injury, or in peculiar circumstances has not been called into action. As leaf-buds are axillary, so branches are not elongated, strictly speaking, by means of leaf-buds, but by a prolongation of the axis of the original leaf-bud from which it arose. This distinction is, however, very subtle and unnecessary; for the terminal scaly bud, though only the undeveloped portion of a leaf-bud, is so similar to regular leaf-buds in the external as well as internal structure, that they cannot be distinguished but by their position. De Candolle indeed calls them all leaf-buds, and we ourselves feel inclined to admit the idea of a terminal leaf-bud; but, while we do so, we must add, that from the terminal being really only a portion of an axillary one, it must be viewed as a modification of the axillary; and therefore, although appearances be sometimes against us, we must again repeat that all leaf-buds are axillary. Spurious leaf-buds, or gemmae as they are called, sometimes capable of producing branches and leaves, or even new individuals, are frequently scattered irregularly on the stem or branches, as, for example, on the elm, where they are abundant; but these must not be confounded with true leaf-buds. The leaf-buds, the development of which depends on the rise of the sap, have the outer or lower scales or leaves first expanded; and this same law ought to hold with regard also to their successive development. And such is the case in some trees. But the extremities of the branches The summit of branches or stems is usually green, soft, and herbaceous; and when the primary stems do not rise above the surface, but only the tender branches, that plant is termed herbaceous, in opposition to those with a perennial stem. An herbaceous stem generally dies down to the ground every year. A perennial stem may be succulent or fleshy, woody, shrubby, or somewhat shrubby; but these terms bear their own meaning. Linnaeus devised for expressing the duration of plants four very simple marks, which have been adopted by nearly all botanists. These are, \( \odot \), to denote annual; \( \delta \), biennial; and \( \varphi \), perennial; while \( \mathfrak{h} \) indicates a shrub or tree. De Candolle, however, has somewhat changed these and added others. He adopts four principal signs, \( \odot \), \( \varphi \), \( \delta \), and \( \mathfrak{h} \). The first relates to a plant called monocarpic, or which flowers and fructifies only once; the second denotes a rhizocarpic plant, which has herbaceous stems that die down to the ground every year; the third applies to a caulocarpic one, whose stems are straight and perennial; and the last marks a climbing plant. The first, third, and fourth of these, being indefinite, are divisible into several others: Thus, \( \odot \), shows the life of the plant is only for one year; \( \varphi \), for two years; \( \delta \), that it is many years before it flowers, but after which it dies. Again, \( \mathfrak{h} \) indicates a suffructicose plant, or one that though shrubby does not elevate itself more than a foot or two; \( \mathfrak{h} \), denotes a shrub of from two to ten feet high, in which the branches arise from the base of the stem; \( \mathfrak{h} \), marks a small tree of from ten to twenty-five feet high, and whose trunk is without branches at the base; and \( \mathfrak{h} \), is a decided tree upwards of twenty-five feet. As to the symbol for climbing, \( C \) marks a plant that climbs to the right, and \( J \) one that climbs to the left. To these the same botanist has added \( \Delta \), to point out an evergreen.

On examining the trunk or branch of an ash or oak tree, we perceive in the centre a mass of spongy cellular tissue, called pith. Around this, and inside of the wood, are placed a series of spiral vessels and ducts, constituting the medullary sheath. This communicates on the one side with the pith, and on the other with the medullary rays, leaf-buds, and veins of the leaves. Next we find the wood, consisting of concentric layers, one of which is formed every year. These layers are composed of cellular tissue, woody fibre, and ducts, and are traversed by the medullary rays composed of cellular tissue, and connecting the centre with the circumference. The fully formed or central layers are called the heart-wood, and the exterior the albumen. The bark surrounds the wood. This may be seen to have the same number of concentric layers as the wood, but of these the hardest or most fully formed is exterior, and the youngest interior. The liber is that portion of the bark which is successively formed next the wood. Each concentric layer, whether of wood or bark, consists of two strata, the one of woody fibre and ducts, the other of cellular tissue, of which the latter in the wood is interior, and in the bark exterior; so that wood and bark may be viewed as similarly constituted of woody fibre and pith; which last, however, in the bark, is on the outside. Between the liber and albumen is formed in spring a viscid secretion called cambium. The matter which causes such plants to increase in diameter has been found by experiment to descend; but the investigation of this subject belongs more to vegetable anatomy and physiology. Suffice it to say, that such an appearance as we have above described takes place in a very great proportion of vegetables; and from the circumstance of their receiving the annual increase between the outside of the old wood and inside of the old bark, some botanists have termed such plants Exogenous (Exogene). There are other plants, however, in which no such distinctions exist, and where the stem is formed of bundles of ducts and spiral vessels interspersed through a cellular tissue; and this is surrounded by a stratum of cellular tissue and woody fibre, different from bark, inasmuch as it cannot be separated from the stem itself. Such plants have their diameter increased by the addition of central vascular tissue and ducts, and are therefore called Endogenous (Endogene). Both Exogene and Endogene containing spiral vessels, are called vascular, in opposition to another division of vegetables, the cellular (cellulares), in which they do not exist; but as these plants do not spring from seeds, we shall pass them over at present.

Occasionally, projections from the medullary sheath reach the circumference of the stem and branches, forming what are called nodi, to which are attached leaves and leaf-buds; and the spaces between these nodi are called internodia. The tuber of the potato seems to be a collection of these nodi and leaf-buds (there called eyes), the leaves being abortive from the tubers being formed under ground.

The stem peculiar to the grasses and other allied tribes is termed a culm (culmus). This is simple, or rarely branched, generally hollow within or fistulose, and separated at intervals by knots or partitions, from which issue the leaves.

The stem may be simple or branched, and with the branches may be cylindrical or conical; round (teres) or angled; smooth (levis), furrowed, glabrous (free from any processes), or rough, or pubescent, or hairy. These terms, bearing the same signification in botany as in common language, need no definition. Among Endogenous plants, from the abortion of leaf-buds, the stems are usually cylindrical and unbranched; while, from the leaf-buds being almost always developed in the Exogene, the stems are generally branched and conical.

Belonging to the stem we may take notice of two processes. The one is a spine (spina), which always arises from what was a leaf-bud; it is therefore a kind of branch, and must not be confounded with the other process, or prickle (aculeus), which does not spring from leaf-buds, and is a mere dilatation of the cellular portion of the bark.

Leaves (Folia).

Leaves are those expansions which issue laterally from the stem and branches of plants. They take their origin

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1. The Linnean character \( \delta \) has been employed by De Candolle to mark a flower or a plant that bears stamens and no pistils; and, to correspond with it, he has recommended the adoption of \( \varphi \) for a plant with pistilla and no stamens; \( \mathfrak{h} \), according to him, designates a plant which has flowers containing both.

2. To save our readers the trouble of referring at every step to the article on Vegetable Anatomy, we shall give here an explanation of the principal elementary organs:

1. Cellular tissue, or parenchyma, is composed of transparent vesicles, variously colouring with each other. 2. Woody fibre is a tissue consisting of elongated tubes, similar to the vesicles of cellular tissue, and is therefore often also called elongated cellular tissue. 3. Spiral vessels are formed of elastic tissue, twisted spirally into the form of a cylinder, and capable of being unrolled. To these alone the name vessels (vasa) ought to be given; and hence they are always to be found in the vascular tissue of plants properly so called. 4. Ducts are elongated, transparent tubes, composed of a tissue that is not capable of unrolling.

VOL. V. Glossology from the bark, and are always to be observed, either in a rudimentary or perfect state, immediately below the leaf-buds. They are originally continuous with the stem and nudi, but afterwards, from a cause that does not appear to be yet well understood, an articulation more or less complete takes place, when the leaf falls off. Very few instances occur where there are no leaves on the stem, as in the genera Orobanche, Lathrea, and Cuscuta, and even then there are rudimentary leaves in the shape of scales or tubercles.

The first thing we have to attend to is the position of the leaves. Those situated near the root are often larger, and of a different shape, from those higher up the stem; and the former are termed radical, the latter cauline leaves. We usually observe, that as these approach the extremity of the branches which bear the flower, they decrease much in size, assume a different form and colour, and are termed floral leaves or bracteas. Of these we shall afterwards have occasion to speak, when we come to the inflorescence of plants.

When the stem or branch is cut through, several leaves are sometimes found in the same horizontal plane. When only two are observed, and these opposite to each other, they are usually said to be opposite. It has, however, been lately proposed to term opposite those only, the bases of whose petioles are connected either by stipules or otherwise, reserving to the others the appellation of pseudo-opposite; but this distinction has been hitherto adopted by almost no systematic writer. When more than two are in the same plane, they are said to be in whorls, or verticillate; but, strictly speaking, such are of very rare occurrence; Hippuris and Myriophyllum may however serve as examples. But it is improper to apply this term to the leaves of the genus Galium, in which the two opposite leaves alone bear axillary leaf-buds, the others being mere foliaceous stipules.

When the branch is cut through horizontally, and only one leaf appears in the section, the leaves were said by Linnaeus to be scattered (sparata), or alternate, with little discrimination. More modern botanists have, however, observed that these are primarily arranged regularly; but afterwards so many disturbing causes occur as to render their true disposition scarcely perceptible. By true alternate leaves ought to be understood those only which are placed on two sides of the branch, in such a way that the third leaf is under the first, and the fourth under the second; and when such are close together they are said to be distichous. But leaves are usually placed in simple spirals, in such a way that the sixth is under the first, the seventh under the second, and so on. There are also instances where the spiral is formed of more than five leaves, and hence there may be double, triple, quintuple, or sextuple spirals. The practice, however, still prevails of calling all such alternate in which the spiral is not very evident.

Of these two systems the type of the verticillate is the opposite, while that of the spiral is the alternate; and cases even happen where the one of these seems almost to pass into the other. Thus, in Exogenous plants, although the leaves may be opposite to each other on the lower part of the plant, they often assume the spiral direction above; and, in the Endogenous, although the lower leaves be in a spiral, the upper ones are sometimes verticillate. This induced Desfontaines to institute a close analysis, by which he discovered a remarkable relation between the structure of the stem, the number of cotyledons, and the disposition of the leaves, from which we are now enabled to derive a general law, that in all Dicotyledonous or Exogenous vegetables, the leaves are primarily opposite, or verticillate, but may become alternate, or form a spiral, according to the mode of growth of the plant; and that in all the Monocotyledonous, or Endogenous, the reverse happens, the leaves being primarily alternate, or in a spiral, but afterwards subject to be more or less exactly opposite. Thus, in the position of the leaves we have an auxiliary enable us to determine to which of these two great classes of vegetables a plant belongs.

Some botanists add to the above fascicled leaves (folia fasciculata); but these are combinations of which both systems are susceptible. Thus, in Aspalathus, where the three leaflets appear to arise from one point, this is a deception caused by the shortness of the petiole. Another case commonly quoted is, when the leaf becomes abortive at the same time that a very short branch furnished with leaves appears from the leaf-bud. Thus, in the barberry, the thorn is the rudiment of the real leaf; and what we call leaves are new leaves placed close together on a very short branch, and belonging to the leaf-bud. In the pine tribe the sheath is the rudiment of the leaf; while the two, three, or five leaves within it are the first leaves of an abortive branch. The cedar exhibits and explains this very easily; for in the early part of spring, the leaves are fasciculated; but in summer, when the leaf-buds or axillary branches have time to elongate, the leaves become alternate.

A leaf consists of the petiole, the lamina or limb, and a pair of stipules; but sometimes only one of these three parts can be observed. The petiole is that which connects the lamina with the stem, and through it the bundles of ducts and spiral vessels pass before they branch out in the limb. Its form is usually cylindrical or slightly channelled above; but it sometimes happens that it is flattened, and presents on each side a foliaceous appendage, when it is said to be margined, as in Dionaea muscipula (fig. 41, b). This margin is frequently contracted at regular intervals; and from each contraction in a compound leaf springs a leaflet. We often find, however, that the leaflets are abortive, in which case the petiole may easily be mistaken for the lamina; and this is indeed what is called by some a lomentaceous leaf. But more commonly a terminal leaflet remains, although the others be abortive, as we see in the orange tree; and to distinguish the two kinds we must be much guided by analogy. This confusion is however of little consequence; for as we may regard the longitudinal nerve of the leaf as a prolongation of the petiole, the limb or lamina itself may be viewed as a margined petiole.

The fibres that pass through the petiole, and which in Exogenous plants arise from the medullary sheath, and in the Endogenous from the bundles of vascular tissue, sometimes in the former class, instead of being united from the base into a compact bundle, as more commonly happens, spring side by side from various points more or less round the branch. The base of the petiole is thus plane, and is ampelicaule or semi-ampelicaule, or perhaps even sheathing (vaginatus). Before the fibres enter the lamina, however, they tend to one point, so that the upper portion does not differ from a common petiole with a rounded base. This expansion of the base of the petiole is to be seen in a remarkable manner in the upper leaves of Bugleorum perfoliatum and some others, where it has all the appearance of a foliaceous limb.

Towards the summit of the stems of the Umbelliferae, the lamina and the cylindrical part of the petiole frequently disappear, nothing remaining but the sheathing base. In Lathyrus Nissolia this happens to all the leaves, and there the sheathing base becomes more dilated than usual. The affinity derived from other considerations between Pyrola and Monotropa shows that the scales of the latter are petiolar sheaths, and in the Orobanche tribe they must be viewed in the same manner.

It happens sometimes, especially when the lamina is not developed, that the petiole, without being sheathing Glossology at the base, expands throughout its whole length, and takes a state intermediate between foliaceous and petiolar. This has received the name of *phyllodium*; as in many species of *Acacia* from New Holland, some of which when young present a slender petiole and a bipinnate leaf, but afterwards lose their leaflets by the dilatation of the petiole.

Sometimes the petiole is elongated beyond the lamina, or perhaps in compound leaves the terminal leaflet may have no lamina but only the midrib, while the petiole or midrib retains its usual cylindrical figure, becomes very long, twists spirally, and then constitutes a tendril (*cirrus*) (fig. 37, a). In others, though rarely, the leaves are abortive, and the petiole remains straight and cylindrical. In some plants with compound leaves, as in *Astragalus Tragacantha*, the terminal leaflet becomes abortive or is changed into a spine, when the petiole is said to be spinescent.

The lamina of the leaf next claims our attention. This is an expansion of the parenchyma of the petiole, and commences where the bundles of vascular tissue that traverse the petiole begin to diverge from each other and form what are called the veins of the leaf. The divergence of these fibres, says De Candolle, is in two different ways. They either separate, making with the base or its prolongation an angle properly so called, and most frequently an acute one, when the leaves may be said to be *angulineered*; or they form on the base or its prolongation a curvature, when the leaves may be termed *curvilineered*. The former structure is essential to the Exogenous, the latter to the Endogenous. Among those, the nerves of which form an angle, there are four forms.

1. Leaves *pennineered* (fig. 14), where the petiole is prolonged into one longitudinal nerve, which on both sides sets out lateral nerves, as in the Spanish chestnut. In a linear leaf these lateral nerves must be all equal in length; in an elliptic, oval; or orbicular leaf, those about the middle must be longer than those at the base or summit of the leaf; in an ovate one, the longer nerves are below the middle; in an obovate leaf, above the middle. When the lower pair or two lower pairs of nerves are much larger than the others, and almost the size of the midrib, as in the Jerusalem artichoke, the leaves are said to be *triplineered* or *quintupleineered*.

2. Leaves *palmineered* (fig. 10), where several nerves diverge all at once from the base of the leaf.

3. Leaves *petineered* (fig. 11), where several nerves radiate from the apex of the petiole in a plane different from the direction of the petiole. It results from this disposition that the lamina does not appear at first to be a prolongation of the petiole, but rather a disc placed at its summit. It is evident, when the point of attachment is near the margin of the lamina, that we should have almost a palmineered leaf; indeed in some plants these two forms occur promiscuously.

4. Leaves *pedalineered*, where the central nerve is very short, but setting off on both sides two strong diverging lateral nerves, which, instead of being branched alike on both sides, present almost no lateral nerves on the outer side; whilst, in the inside, secondary nerves spring out almost parallel to each other. This form is of rare occurrence, but may be seen in some passion-flowers.

The curvinerve leaves may either have their nerves converging or diverging; but these require little illustration.

In Exogenous plants the veins branch in various directions, anastomosing, and forming a kind of net-work. In Endogenous plants they are nearly parallel to each other, being connected by single transverse unbranched veins.

To this the Coniferae and Cyadaeae form perhaps the only exceptions: these have the stems of the Exogenous, but the same arrangement of the veins as in the Endogenous.

The veins of some leaves are capable of producing from their extremities gemmae similar to those we have described as occurring on the stem and branches. These gemmae usually arise from the margin; but as the vein must be open, or have a stoma, as it is anatomically called, at the point of insertion; and as such stomata, though frequent on the under side, have been rarely observed on the upper surface; so the gemmae are seldom or never produced on the upper side.

A leaf is either simple or compound. It is *simple* when its lamina is entire (*folium integrum*), or when, if separated into several divisions, these segments are not articulated with the petiole. The position and ramification of the nerves have great influence in determining the shape of the leaf. Of those that are entire, the simplest of all forms is the *linear* (fig. 12), where the margins are parallel. By the central position of such a one being slightly dilated, we have an *oblong*; when more dilated, an *elliptical* leaf (fig. 13); and when much so, an *orbicular* one. When the dilatation is below the middle, we have an *ovate* (fig. 14); when above the middle, an *obovate* leaf (fig. 15). When the oblong tapers gradually into a point at the apex, it becomes *lanceolate* (fig. 16). If a leaf be very narrow, and taper upwards from its base, it is *subulate* (fig. 17); and when long, narrow, stiff, and sharp, it is said to be *acicular* or *setaceous* (fig. 18); when narrow and very slender, it is *filiform*. When an elliptical leaf tapers much below, so as to be narrow at the base, and broad and rounded at the summit, it becomes *spathulate* (fig. 19); and when narrow at the base, and truncated or somewhat squared off at the top, it is *cuneiform*. Such are the principal forms. When almost any of these are produced at the base, so as to have two lobes on each side of the petiole, they are said to be *cordate* or *heart-shaped* (fig. 20 and 21) when the lobes are rounded; *segitate* (fig. 22) when acute and scarcely diverging; and *hastate* (fig. 23) when acute and diverging much outwards. When an orbicular leaf becomes cordate at the base, it is called *reniform* (fig. 24).

Leaves, or rather the lamina of leaves, are either sharp-pointed or acute, *pungent*, *mucronate*, or *acuminate*, or they are blunt (*folia obtusa*), (fig. 15, 24); when such a leaf has a small sinus at the apex, it is *retuse* (fig. 25); when the sinus is deeper, as if a piece had been cut out, it is *emarginate* (fig. 26); and when still more so, *obcordate*; till by degrees we have *bifid*, two-lobed (*folia biloba* (fig. 27), and *bipartite*. What is called the appendage (fig. 41, a) in *Dionaea muscipula* is a two-lobed lamina. From the gradual transition of one form into another, botanists might long ago have learned the little importance to be attached to any individual shape; unhappily, however, for science, species have too often been multiplied on such weak grounds. In studying the phytographical department, we would recommend, that either in describing, or endeavouring to understand a description, each form should be taken with a considerable latitude of meaning, and as subject to vary into the others on either side.

A divided leaf may be *cleft* (*folia trifida*, *quadrifida*, &c.), or, if the divisions be deeper, it is *lobed* (*folia triloba*, &c.), and, when deeply cut, *partite* (*folia tripartita*, &c.); but when the divisions are deep and unequal, the leaf is *laciniate* (fig. 28). When a leaf is rounded at both extremities, but contracted in the middle, it is *panduriform* (fig. 29) or violin-shaped; and when there are more than

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1 The terms *ovate* and *obovate*, although generally adopted, are incorrect; they ought to be *ovat* and *obovat*. A truly ovate leaf refers to thickness as well as surface. It has indeed the shape of an egg, and oval is the longitudinal section of such. Glossology, one contraction on each side, as in the oak, it is sinuated (fig. 30). When a leaf is divided laterally into lobes more or less deep, it is pinnatifid (fig. 31); when these lobes are very narrow and nearly parallel, it is pectinate; when the lateral lobes are acute and recurved, it is runcinate (fig. 32); when the terminal lobe of a pinnatifid leaf is round and larger than the others, the leaf is lyrate (fig. 33); when a leaf is so deeply divided laterally that the lobes are only connected at their base, it is pinnaeipartite; and when the lobes are completely isolated, it is pinnatisect (fig. 34). Linnaeus, as well as many modern botanists of eminence, called the last pinnate, and referred it to a compound leaf; but the transition from the entire leaf to the pinnatisect shows distinctly that the latter is but a simple leaf, of which all the parenchyma has not been developed.

A divided leaf may have its lobes again divided, when it is said to be bi or tri-pinnatifid, &c.

A compound leaf is when the lamina is articulated with the petiole. It is either digitate or pinnate. Leaves are digitate (fig. 35) when all the leaflets start from the same point at the apex of the petiole, as in the lupines; in the orange there is but one leaflet; in other plants three, four, or more. Leaves are pinnate when the leaflets spring out laterally from the common petiole, and are oppositely (fig. 36) or alternately pinnate, according as these leaflets are opposite to or alternate with each other; and are imparipinnate (fig. 36) or paripinnate when there is, or is not, a terminal leaflet. When there is but one, two, or three pairs of leaflets, the leaf is said to be unifoliate (folium unijugum), bifoliate, trifoliate (fig. 37), &c. A decompound leaf is where the common petiole is divided into secondary petioles, each of which bears a foliole or leaflet. Of these, when the secondary petioles all spring from the apex of the common petiole, the leaf is digitato-pinnate; or when there are only two secondary petioles, conjugato-pinnate (fig. 38). When each of the secondary petioles bears only one pair of leaflets, the leaf is bigeminate (fig. 39); and when the secondary petioles spring out as leaflets do in a pinnate leaf, but are themselves pinnate, the leaf is bipinnate (fig. 40). Decomposed leaves may be again divided, when they are called supradecomposed (folia supradecomposita).

The margin of the divisions of a simple or compound leaf is variously modified. It may be very entire (integerrimum) or crenulate, when furnished with little projecting points; or dentated, when the margin presents small radiating acute teeth, that neither incline to the bottom nor to the apex of the leaf (fig. 21); or serrated (fig. 14), when the teeth are inclined; or thorny, when the teeth are narrow, stiff, and sharp (as in the holly); or ciliated, when there is a series of hairs along the edge, like a person's eye-lashes.

With regard to the expansion, surface, pubescence, consistence, form (we do not mean by this the superficial shape, but the shape as a mass, of which the other is but a section), and colour, it is unnecessary to say anything, having restricted ourselves to a more general view of the subject.

Leaves unite very easily either with each other or with the stem. When two have their margins close together at the time of their development, they often unite quite accidentally; but there are some plants in which such a union is not accidental, but constant. In the honeysuckle a transition may be observed from the leaves perfectly distinct, to those that are joined by their bases. The genus Bauhinia presents many instances of leaves being united by their edges: a palmnerved leaf may thus be viewed as composed of several penninerved leaves soldered partly together. When leaves unite to the stem they are termed decurrent; and this may be either caused by the middle nerve coalescing with the stem, as in the floral leaves of Glossogyne, or by the adherence merely of a prolongation of the parenchyma of the leaf.

Some botanists speak of an appendiculate leaf, in which there ought to be an extraneous body attached to it; but the more the structure of the different parts is studied, the fewer instances are to be recorded. Thus a cirrus or tendril is usually an abortive leaflet, or petiole, or stipule. The supposed appendage of Dionaea muscipula (fig. 41, a) is the real lamina of the leaf, while the supposed leaf is the petiole (fig. 41, b). The pitcher of Nepenthes (fig. 42, a) is also now regarded as the leaf; and the lower portion (fig. 42, c) the petiole, which is partly margined. This plant, however, is scarcely yet completely understood; probably the lid (fig. 42, b) to the pitcher alone is the limb of the leaf; while the petiole at first consisting (as in the lower leaves (fig. 43, 44) that arise from the plumule on germination) of a mere pitcher, afterwards elongates (fig. 42, c, a) into a margined portion, a cirrus, and a pitcher. In Sarcoecia, said also to have a pitcher-shaped leaf, the petiole forms a hollow sheath with the lamina or lid at its apex.

Stipules (fig. 37, b) are those small foliaceous organs sometimes situated on each side at the base of the petiole. They never occur in the Endogene, nor in any Exogenous plants that have sheathing petioles, and are rarely found in genera with opposite leaves. Their presence or absence seems to be eminently connected with the general symmetry of plants, for they exist or are wanting in all of the same family. They have frequently the same structure, and are often transformed into leaves; even leaf-buds have been observed in the axils of some of them, so that they may be viewed as rudimentary leaves. Stipules sometimes change into spines; but the spines in Acacia are not stipules, but prolongations of a swelling of the stem under the leaf, which serves it as a kind of support. This is evident from there being frequently real stipules independent of the spines; but usually, when the spines are formed, the stipules above them are abortive. Stipules seem occasionally to change into tendrils, and this is the most probable explanation of the lateral tendrils of the gourd and cucumber tribe. They are in general smaller than the leaves; but in Lathyrus aphaca they are remarkably large, while the leaves are entirely abortive. Those at the base of the same petiole are not always alike; one of them even in some plants becoming abortive, while the other persists. Stipules that are situated between the petiole and the branch are intrapetiolar; and, in the case of opposite leaves, when they are between the two opposite petioles, they are interpétiolar, or intrafoliacous. Stipules sometimes unite together, and when so, if they form a sheath round the stem, they are called ocreae; and if the union take place between the petiole and the stem they are termed intra-axillary. They also often adhere to the petiole by their margins, and then one must use the greatest caution not to confound with them the cellular appendages of the petiole itself.

Leaves arise on the young shoots, or already exist Vernation more or less developed when the shoot begins to appear. At this period the external leaves frequently take the appearance of scales, and serve as a protection to the others. The compact mode in which the young leaves are arranged before expansion is called the vernation or gemination, and is determined by different causes, viz., their position on the stem and mode of adherence, the disposition of the principal nerves, and the different degrees of separation or union of the parts. All the appearances resulting from these may be reduced to three classes: 1st, They are folded or rolled longitudinally on the midrib, which remains straight; or, 2d, they are folded or curved, The usual state of Exogenous plants is to have the leaves so folded that the two parts of the lamina on each side the midrib are applied to each other by their upper surface; but this is much modified by other circumstances. Thus, when two penninerved leaves are strictly opposite, and another pair at right angles to these, they are only half folded, in such a way as to inclose the inner pair: and such a vernation is termed opposite (fig. 45). When less decidedly opposite, one of the sides of each leaf is exterior and the other interior (fig. 46), and then the vernation is half-equitant (semicamplexus); and when the leaves are alternate or spiral, they are each of them folded by themselves, and placed side by side, when it is called conduplicate (fig. 47.) Penninerved leaves being considered as composed of several penninerved ones united by their margins for some part of their length, each of the divisions has a tendency to be folded, exhibiting a plicate vernation (fig. 48). The leaflets of palmate leaves present of course the same disposition. Some penninerved leaves, although folded together, have the margins rolled outwards, as in the rosemary, and the vernation is revolute (fig. 49); or they may be rolled in, as in the water-lily, and it is involute (fig. 50). These latter peculiarities are very rare among the Exogene, but common among the Endogene. When the young leaves are so narrow that they are not folded, but cover each other without any apparent order, they are said to be imbricated. Such plants as have a petiole that embraces the stem for some length (which chiefly happens among the Endogene) present a slightly different disposition. Here most of the leaves are reduced to a dilated petiole, and are simply curved and imbricated the one over the other, as in the coats of what are erroneously called bulbous roots (fig. 8); but there are other plants with a sheathing petiole, that show an inclination to a longitudinally-folded leaf (as in the Iris) as much as if they had a midrib, and the vernation is equitant (fig. 31): so called because, as they are alternate, each of them rides upon or embraces by its two margins the two margins of the leaf that follows it. Another disposition, but almost peculiar to the Endogene, is the convolute (fig. 52), as in the scitamineae, where the limb is rolled round one of its margins on an axis. The vernation is termed replicate when the leaf is so folded that the upper part is applied to the lower, as in the aconite; and circinal when, instead of being folded, it is rolled in such a way that the apex serves as an axis; which last curious structure may be observed in the genus Drosera, and in the Cycadeae.

**CELLULAR PLANTS.**

The observations hitherto made relate almost exclusively to Vascular plants, the terms relating to the external forms of which alone can be applied also to the Cellular vegetables; so that, before proceeding to the reproductive organs, we may devote a few lines to such as come under the latter denomination. And here we must draw a line between such as are furnished with ducts in addition to mere cellular tissue, and those in which we find an entire homogeneity of structure; and, for the sake of distinction, we shall call the former ductulose, and the latter educulose.

**Ductulose.**

All belonging to this section, on account of the presence of ducts, and in some instances apparently of stems, more than one author of eminence has classed with vascular plants; but there are no spiral vessels present, and although it is often difficult to distinguish between spiral vessels and ducts, we prefer to make the characters of the Glossology two great classes of vegetables depend on the presence or absence of the former, rather than of the latter; the more so because we feel convinced, that, with the aid of spiral vessels, and not without them, can true seeds be produced. As ducts are always to be observed in roots, even in the most fibrous, so there is a presumption that true roots exist in all the ductulose. As, however, no spiral vessels occur above the root, there can be no collum or line of separation between stem and root, and therefore the whole plant may be viewed as one uniform body, every section presenting the same structure. On account of the appearance of stems, the ductulose may be said to have an axis.

1. The Equisetaceae must first be noticed. These have Equisetitle or no resemblance to the other ductulose, and almost taccæ as little to the vascular plants. Their nearest affinity is perhaps with the genus Camarina (one of the Exogene). Their vernation is straight. They have no true leaves, but a furrowed fistular stem, in which, under the cuticle or external membranous coating, so much silic is deposited as to render some of the species of great use in polishing furniture and other household utensils. The stem is moreover articulated, separating at the joints, each articulation being surrounded by a prolongation of the joint below it in the shape of a membranous toothed sheath; the number of the teeth, if not combined, corresponding with the number of the furrows on the stem. The stem is either simple, or has branches articulated like the stem, placed in whorls at their articulations, each whorl consisting of as many branches as there are teeth to the sheath.

2. The Filices or ferns seem to approach very closely to Filices, some of the Endogene, particularly to the palms, in general habit, and also slightly to the Cycadeæ, which form part of the Exogene; but if our ideas be correct, the affinities that have been traced between them have been much exaggerated.

In our estimation, an entire fern corresponds only to a leaf among the vascular plants; and that part which has been called a stem or rhizoma under ground, or a stipes or caudex when erect and above ground, as in the tree ferns, is, we think, analogous to a mere petiole. Each leafy expansion has been termed a frond, without sufficient attention having been paid to its origin. But a frond whose stipes pushes out radicular fibres from its base, is, we think, similar to a simple leaf; while those species whose frond is attached to a rhizoma or caudex resembles a pinnate leaf. Thus the ferns do not resemble vascular plants, but only a portion of one. The vernation of all, with the exception of Ophioglossum and its allies, is circinate like the Cycadeæ; but instead of being rolled inwards, it is rolled outwards, unlike any vascular plant that we remember. As, however, the views here announced have not hitherto been adopted by any botanist, we may, in reference to the terms more generally in use, mention, that every leafy portion which rises above ground is termed a frond, and its stalk or support a stipes. The creeping part under ground or on the surface is termed a rhizoma, and when erect and like the trunk of a tree, a caudex. The stipes is flattish or concave on the side corresponding with the upper surface of the frond, and convex on the other. It is glabrous, or rough, or prickly, or scaly (paleaceous), or downy (pubescent), as in vascular plants. The frond is said to be simple, or lobed, or pinna-tifid, or pinna-tipartite, as in a true leaf. It is even called pinnate when there is no membranous connection between the divisions, although there be no articulation at the base of each. In substance also it may vary from rigid and coriaceous to thin and membranous.

3. Marsiliaceæ. These are either creeping or floating liæææ. Glossology; plants; the former have petioles to what are called their leaves, with a circinate vernation like the ferns. The supposed leaves are of a coriaceous texture, and either consist of three or more wedge-shaped divisions, and are conduplicate when young; or they are entirely abortive, leaving nothing but the petiole, as in *Ptilaria*. Those, again, which float have the leaves closely imbricated and sessile, and resemble the *Hepaticae*, and appear to be involute, or folded together in vernation.

4. *Lycopodiaceae* are seemingly intermediate between the ferns and mosses with which they were formerly confounded. They have either creeping stems or a cormus, with erect branches, which are either round or angled, and provided with leaves. The leaves vary from scotaceous to ovate, are acute, undivided (with only one exception), smooth, and of a thick texture, resembling often in a slight degree those of the pine tribe. In several, however, they are plain and foliaceous; sometimes they are closely imbricated round the stem, or they appear distichous, with generally two other rows of smaller ones, that are appressed, and may be taken for stipules. They have either a middle nerve or none at all. In one genus, the leaves are reduced to mere scattered teeth, and in another they are all radical, long, subulate, channelled above, and convex below. Their vernation is straight. They are usually found on mossy ground, sometimes on trees, rarely in or under water.

*Eductulose.*

These are entirely composed of cellular tissue, so that here we find as much uniformity in their internal structure as diversity in the other classes of vegetables; but, by a strange compensation, their external forms are even more varied than in the higher organised plants.

The entire mass of these vegetables appears to be composed of one substance, which takes different shapes, destined to fill different functions, without actually constituting distinct organs. Persoon, in speaking of the mushroom, has named the whole portion that does not serve for the reproduction of the species a *peridium*; Acharius has called it a *thallus* in the lichens; and Lamaroux, *frons* or *frond* in the algae. De Candolle, again, is disposed to apply the term *thallus* generically to all the nutritive organs combined in the true cellular plants, at least to those of the algae, fungi, lichens, and hepaticae; and it would be well if botanists, who have made these tribes their study, had agreed to drop entirely the terms *leaves*, *stem*, or *roots*, which have no real affinity with those of vascular plants, and can be only applied metaphorically. But as they are generally retained in some of these orders, we will continue also to employ them.

5. The *Musci* or mosses have most affinity with the ductulosae, and approach very closely indeed to some of the lycopodiaceae. What are called their roots consist of slender fibres of a brownish colour, more or less branched and jointed, which spring either from the base of the stem, as in *Phascum*, or along it, as in several species of *Bryum*, in which great part of the stem is sometimes covered with these radicular fibres. The stem is cylindrical, but is said to be compressed, plane, or tetragonal, according to the disposition of the leaves. It is often very short and simple, especially when the plant is annual, but is sometimes branched, either by pushing out roots near the base, or by emitting lateral or terminal branches, each of which denotes usually a year's growth, and they are thus called by Hedwig *innovations*. The leaves arise from the stems, being sometimes collected together at the base, sometimes at the apex, and sometimes alternate or in a spiral: they are sessile, and embrace the stem at their base; and they have the appearance of oval or elongated scales, rarely obtuse, generally pointed or acuminated, and the point is not unfrequently prolonged into a long hair, or twisted like a cirrus or tendril. Only one instance is yet known where the hair-like point is branched. They are usually entire, but in *Diphyacium* and *Buxbaumia* they are laciniate. Some leaves are deprived of all appearance of a nerve, and are entirely formed of a homogeneous cellular tissue; others present in the middle a nerve variable in length; others again two nerves; and these nerves are formed of cells, which by their union imitate the nerves of vascular leaves. The margin is either entire, crenated, toothed, or serrated; and the serratures are sometimes so fine as to cause it to be called ciliated; but these appearances are not occasioned, as in vascular plants, by (as it were) an incision into the leaf, but arise from a mere contraction of the marginal cellules, more or less evident in the same species, and even specimen, in different states of its growth. The leaves, as we have said, embrace the stem, but sometimes in so very oblique a manner as to form two opposite vertical rows, and thus appear distichous, as in *Schistostega pennata*. But this must not be confounded with the structure in that section of *Dicranum* called *Fissidens*, in which the leaf is slightly folded, and the upper portion on each side of the nerve soldered closely together, while the nerve itself is prolonged at the back into an appendage equal to the half of the leaf. Some botanists seem inclined to suppose that these leaves, resembling those of an *Iris*, may be formed by the partial soldering of two closely approximated and obliquely placed leaves; but we are borne out in our view by an examination of the young leaves, either at the very base of the stems, or at the perichaetium, in which they are as in other mosses, the nerve not being yet provided with its appendage.

6. The *Hepaticae* resemble much the mosses, and most Hepaticae of the genus *Jungermannia*. But here there is no trace of nerves; and at the base of the leaves are often to be found leafy appendages or accessory leaves, falsely called stipules, sometimes united by the side to the leaf, and sometimes distinct from it. There are some species of this genus without these appendages, having the leaves vertical, scarcely at all embracing the stem, but having their margins prolonged down its side, so that the stem resembles a petiole furnished with distichous segments. When these segments are united by the edges on each side, we have a foliaceous limb, and such species are called *frondose*, the midrib corresponding to what is termed the stem in the others. Sometimes this midrib is obscure, as in *Jung.epiphylla*; in *Jung.pinguis* it cannot be traced, so that we may pass to the genera *Anthoceras*, *Marchantia*, and *Riccia*, in which we see only a nerveless foliaceous disc, representing both stem and leaves; pushing out from below, the roots; and from above, the organs of fructification. From the supposed existence of a stem and leaves, both musci and hepaticae are said to have an axis.

7. The *Algae* are principally found in water, and consist of expansions, sometimes filiform, sometimes foliaceous, or a mixture of these. Their perfect homogeneousness has been acknowledged by all who have studied them, and thus the appellations of frond or thallus has been given to the whole mass of the plant. They present different degrees of consistence; some being coriaceous and of an olive colour, others cartilaginous and of a rose colour; some membranaceous, and others gelatinous. The

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1 Arnott, Nouv. Disp. des Mousses, p. 27. with the stem: in a few this veil has the appearance of a Glossology ring round the stipes, and is then called an annulus.

REPRODUCTIVE ORGANS.

We now come to the reproductive organs, or those organs essential to the reproduction of the plant; and under this denomination we comprehend all those parts that are situated beyond the leaves. Linnaeus first made the observation, that the parts of a flower were metamorphosed leaves; and this will appear very evident from considering the facility with which any one part changes into another. Thus, leaves gradually pass into bracteas, and the latter have often so much the appearance of true leaves as to be only distinguished from them by their position. Between bracteae and bracteoles there is scarcely a limit; and either of these, when immediately under the flower, is often liable to be confounded with the calyx, or supplies the place of a calyx. Again, between a calyx and corolla there is the closest resemblance; so much so, that when one only was present, it has been a matter of dispute by what name it ought then to be described.—Jussieu and his followers calling it uniformly by that of calyx, but Linnaeus pronouncing it a calyx only if green, and a corolla if coloured; whilst more modern botanists, to avoid a discussion attended with little good, have adopted instead of it the ambiguous term perianth. But horticulture shows this affinity in a still more striking degree; many of the primrose tribe in cultivation having the calyx changed into a corolla placed under the true corolla, and in every respect similar to it. In a double flower, all are aware, the stamens change into petals; and in the water-lily (Nymphaea) it is no easy matter to draw the respective lines of demarcation between stamens, corolla, and calyx. It is more difficult to admit at first the connection between the fruit and the others, instances of the metamorphosis being more rare. Thus, in half double flowers, the fruit, or parts of the fruit, or carpella as they are called, remain often unchanged, as in the peony; but in many truly double flowers, as among the pinks and carnations, every portion of the fruit is actually transformed into petals. On the other hand, in Magnolia fuscata, the stamens actually change into carpels; and we have specimens before us, exhibiting the same change in the Salix Croceana. In some species of Ononis, and the other genera of leguminous plants, in which there is usually one perfect carpel, we have seen it transformed into a leafy process, demonstrating that the carpel is nothing but a folded leaf.

The parts belonging to the flower, though thus primarily alike, yet differ much afterwards, particularly in their physiology. The more foliaceous parts, as the bracteae, calyx, and corolla, serve for the nutriment or protection of the others, which are more immediately called the sexual organs. In several parts of the flower we may distinguish the portions of the leaves of which they are composed, so as to detect more or less clearly the petiole and the lamina. Thus, in a calyx the sepals are usually formed by dilated petioles, although in the roses the lamina also makes its appearance. Of the corollas, the petals present in general a dilated petiole; but sometimes an unguis or claw may be noticed, as well as a limb, conformable to the petiole and lamina of a leaf. Among stamens, the filament is the petiole, while the anther is produced by each side of the lamina being rolled inwards, and forming two loculi or bags. The carpels are formed by the folding of the lamina of a leaf, the ovules arising from the extremities of the lateral nerves. Here the petiole is often wanting, though in several genera of Leguminosae, in the caper plants, and others, it is very distinct.

From what we have now said, it may be laid down as an Botany.

Glossology axiom, that a flower is an assemblage of several whorls of foliaceous origin, arranged above or within each other, so closely that the internodia, or distance between each series, is not distinguishable. But this will be better understood when we come to the definition of the particular parts.

Inflorescence.

Inflorescence is the ramification of that part of a plant intended for its reproduction; or, in other words, it is the mode in which the flowers of a plant are distributed. The organs peculiar to it are peduncles, pedicels, bracteae, and bracteoles or the accessory envelopes to the flowers.

As leaves are lateral, so must also be the parts of the flower, hence we might naturally expect the floral stem or branch to be prolonged beyond it; and this indeed often happens in monstrosities, as in some roses and pear trees; but otherwise the flower absorbs all the nutriment from the branch destined to that purpose. Thus we may state as a general law, that a flower is terminal on the little branch that supports it; and this branch is termed a peduncle or pedicel. The pedicel with the flower being thus precisely similar to a branch and its leaves, the flower-bud which gives rise to such must be analogous to leaf-buds; and the great difference between them is, that the latter elongate indefinitely in the form of branches, while the former do not elongate beyond the flower.

Flower-buds always, therefore, like leaf-buds, are terminal, or arise from the axils of leaves, which leaves are called bracteae or floral leaves; and those leaves which appear on the pedicel, between the bracteae and calyx, are called bracteoles. These are often confounded, but are nevertheless essentially distinct; the former belonging more to the stem, the latter to the flower-bud. Bracteae and bracteoles are often beautifully coloured, the more so, usually, the nearer they are to the flower. When a single one is rolled together, highly developed and coloured, and is placed at the base of the form of inflorescence called a spadix (fig. 53, b), it is named a spathe (fig. 53, a); and the upper ones, arising among the flowers themselves, are termed spatheoles. When several are verticillate, or densely imbricated around the base of the form of inflorescence called an umbel or capitulum, they are termed an involucre; and those at the base of each partial umbel are called involucella. In the grasses there are usually two at the base of the spikelets, which receive the name of glumes; while the small ones surrounding each floret in the spikelet, called glumelle or paleae, may be viewed as involucella. Small imbricated bracteae are often called scales, as in the thistle and artichoke. On dissecting the capitulum of flowers of many of the Compositae, small colourless bracteae may be perceived at the base of the florets;—these have received the name of paleae, but they appear to be a mere continuation or modification of the scales of the involucreum.

With regard to the axis of inflorescence and its bracteae, sometimes the axis itself, but more usually the branch which springs from it, is termed a peduncle. These peduncles often bear bracteae, from the axils of which arise secondary peduncles. The same may again happen, and the ultimate support to the flower is then termed a pedicel. A pedicel may be clothed with bracteae; but these have no flower-buds in their axils, and therefore each can only, strictly speaking, bear but one flower. In the honeysuckles there appear to be two flowers and two fruits to each stalk, but this is caused by the combination or union of the two pedicels that terminate the axis. When two or more pedicels spring near to each other from the axis of inflorescence, the axis is termed a rachis. Those axes that spring out of the earth, and bear no true leaves, are denominated scapes. Peduncles are usually cylindrical or slightly compressed; in Glossoxylophyllum it is said to be flat or foliaceous, but this appearance originates rather from the expansion of the axis or rachis than of the peduncle itself. In the case of an umbel, the axis tends to dilate at the apex, and this dilatation seems to depend on two causes: it is either in proportion to the number of flowers that ought to be on the summit, or it becomes the larger the more sessile the flowers are on the horizontal expansion. That kind of umbel found in thistles and other compound flowers is a remarkable illustration of this: the expansion on which the flowers are situated here bears the name of receptacle; some few botanists calling it also, in particular cases phoranth or climanth. These receptacles are sometimes quite flat, sometimes conical or cylindrical, and sometimes concave; and in the fig the margins of the receptacle are so approximated as to represent a bag, on the interior surface of which all the flowers are seated. By many botanists the axis of inflorescence is termed the peduncle, and the peduncles pedicels. But it is impossible here to lay down any certain rules by which these may be understood, the same author at different times using the same terms with a different meaning.

The inflorescence of plants is very various, and depends entirely on the power of developing the flower-buds in the axils of the bracteae. Two points are, however, common to all the forms: all must be axillary, or a modification of that, and have the flowers terminal on the peduncles or pedicels. They may be reduced to two classes: simple, when it is formed by the development of one bud and one branch; or compound, when it is formed by the development of several buds or branches.

Simple inflorescence.—When a flower-bud gives rise to only one flower, terminal on its peduncle, and the axis of the plant does not elongate beyond the bud, the flower is commonly called terminal and solitary. When, however, the axis continues to elongate, and the bracteae retains the form and size of a leaf, the flower is called axillary and solitary. But if the buds, instead of giving rise to one terminal flower, have the axis elongated, bearing several flowers, and each flower on a peduncle, a raceme is produced; and when each flower is sessile, or placed in the axil of the bracteae, without a peduncle, a spike is formed. The difference between these two is very slight, or, more properly speaking, a spike is a mere conventional term, to imply those cases where the peduncle is scarcely perceptible; and, by the aid of horticulture, the one is frequently made to pass into the other. When the bracteae are nearly equal in size and closely imbricated, and the spike articulated with the stem, it is termed an amentum or catkin; but this articulation is often not to be detected; thus, in some willows, the male catkins fall off, while the female are permanent. The real spikes of the grasses are commonly termed spikelets or locustae; and when we there speak of the flowers being in spikes or panicles, we actually mean that the spikelets are arranged in spikes or panicles. The spadix (fig. 53, b) is a sort of spike, in which the flowers are closely packed together upon a succulent axis, which is enveloped in a coloured convoluted bractea or spathe: the spadix is usually simple, but in some palms it is branched. A raceme differs, as we have said, from a spike by having the pedicels that issue from the bracteae more elongated. When a raceme has its peduncles spreading, elongated, and bearing bracteae, and pedicels again arising from these bracteae, a panicle is formed. Usually in these two the lower peduncles are only slightly longer than the others; but when they are very long, and the upper ones very short, it is commonly termed a corymb. But this appellation was given before the subject of inflorescence was properly studied, and with De Glossology. Candolle we feel inclined to adopt here the terms corymbose raceme, or corymbose panicle. When the axis of a raceme is so very short that all the peduncles issue from one point at its apex, we have a simple umbel; and when the same happens to a panicle and to its branches, a compound umbel is formed. In these frequently the bracteas fall off early, or are abortive. A capitulum may be either a spike, raceme, or umbel, in which all the flowers are placed together in a globular head. Capitula also differ from each other by the form of the axis, many kinds of which may be seen among the Compositae. Now, as all these different kinds of inflorescence spring from a solitary flower-bud,—and as a flower-bud is quite analogous to a leaf-bud,—and as in a leaf-bud the outer or lower part is first developed;—so in a spike, a raceme, a panicle, an umbel, or a capitulum, the lower flowers are first expanded, and this mode of flowering or order of expansion is called centripetal.

Composed inflorescence, or when the inflorescence is the result of the expansion of several buds or branches.—The most perfect instance of this is a true corymbus. Here the axis of the plant assumes the appearance of an axis of inflorescence, developing flower-buds which follow the centripetal order of expansion; but as it is a continuation of the axis of the branch, and as we have already observed that those leaf-buds nearest to the summit are first developed, so, in a compound inflorescence, the flower-buds towards the extremity of the axis are first evolved, and the lower ones the last. In a corymbus, then, each particular branch follows the centripetal law, while the whole mass of inflorescence proceeds in an inverted order. Although we have only referred to the corymb generally as a mode of inflorescence, individually it resembles a raceme, of which the lower flowers have long, and the upper ones short pedicels. The Achillea millefolium will well illustrate the corymbus; each of what is commonly called the flowers of such a plant being a capitulum. Now, let us suppose that the capitulum of such an inflorescence is by some means reduced to a solitary floret,—and approximations to this are to be observed in many Compositae,—we shall then have a cyme, in which the solitary central flower is first developed, and, lastly, the lower ones. This kind of expansion is called the centrifugal. Viewing, with De Candolle and Roepel, the terminal bud by which a branch is prolonged, as similar in all respects to a true leaf-bud, and supposing in the same way the existence of a terminal flower-bud, this kind of inflorescence has received the name of terminal or definite, because the flower being supposed to occupy the extremity of the branch, no more can be formed beyond it; while the centripetal inflorescence has been termed indefinite or axillary, because the axis being never terminated by a flower-bud, it may be elongated until there be no more juices left for the further development of the flower-buds. The term cyme is usually applied to those cases in which the primary branches issue from the same point, while the smaller branches are unequal, starting from different points; but elevating the flowers so that they may be nearly all in one horizontal plane, as in the elder or dogwood. But this is not always the case: the central portion may be elongated; and then, when the peduncles and pedicels are relatively opposite to each other, as in Erythrea, we have what are called dichotomous cymes. A fasciculus, on the other hand, is a contracted cyme, in which the lateral branches are very short, and the flowers are clustered together, as in many of the pink tribe. A glomerulus is when the cyme is so contracted, and the ramification is so little apparent, that it has been usually confounded with a true capitulum. This disposition is of rare occurrence, but is to be observed in some Compositae. The last form of inflorescence we shall notice is a thyrsus; and this may be conceived to be composed of cymes, arising from the axils of the leaves of a branch as it is successively developed. Thus the sage, Pl. CXII., the thyme, and the labiate plants, exhibit a thyrsus. The stem or branch is prolonged indefinitely, of which the lower flowers first make their appearance; but the inflorescence that proceeds from the axil of each leaf is a true cyme, in which the terminal flowers are first expanded.

If we be correct in what we have stated, the centrifugal mode of expansion is a reduced form of the centripetal, combined with the mode of development of branches. It ought, therefore, to be scarcely distinguished from the other; and cases do occur only referable by analogy. Roepel and De Candolle, who admit the existence of terminal flower-buds, observe that the terminal mode has two opposite bracteas, while the axillary has but one; and they apply this test with great ingenuity to the case of a solitary peduncle and flowers, in order that it may be referred to one or the other of the two classes.

Torus.

The torus, or the proper receptacle of the flowers, is an expansion of the pedicel, from which spring the petals and stamens, and seems to be formed by an abortion or partial development of one or both of these parts. Although, therefore, not properly by itself an organ, it is of great importance in the structure of flowers; for not only do the stamens and petals arise from it in the state in which they usually appear to us, but even when these are transformed into nectariferous glands, or into those doubtful bodies sometimes confounded with stamens and sometimes with petals. These appearances may therefore be met with either outside of the petals, or inside of the stamens, or between these. Usually, however, the torus is inconspicuous, and is reduced to a narrow circular space between the calyx and the pistil. When this zone is under the ovary the petals and stamens are said to be hypogynous, and the plants are termed thalamiflora. But frequently the external part of the torus extends itself along the bottom or the interior of the calyx, and the stamens and petals are said to be perigynous, and the plants are called calyciflora. When the inner portion of the torus expands along the pistil in a greater or less degree, the stamens and petals then seem to arise from the pistil, and are denominated epigynous. But there is still another case, when the torus extends both along the calyx and the pistil at the same time; and a necessary consequence of this is, that the tube of the calyx adheres to the pistil. The petals and stamens thus spring from a zone round the apex of the fruit, and between it and the calyx, and seem to be seated on the fruit itself; an appearance which has induced botanists to apply to it also the term epigynous. But if these two kinds of epigynous insertion were to be considered as but one, so ought in the same way what is called perigynous to be viewed as a modification of the hypogynous; for in the perigynous the torus, though connected with the calyx, was distinct from the fruit, and as much under it as in the true hypogynous; and, strictly speaking, both the perigynous and second kind of hypogynous may be regarded as combinations of the other two. Most modern botanists have, however, considerably altered the signification of some of these terms, especially when speaking of the insertion of the stamens. According to them, when the stamens contract no adhesion with either the calyx or the pistil, they are hypogynous; when they do arise from the calyx, but are free from the pistil, they are said to be perigynous, and such does not differ from the view we have taken above; but when the stamens contract an union with both the surface of the calyx and the pistil, they are Glossology termed epigynous, while the true epigynous insertion, or where the stamens are united to the style, but free from the calyx, receives the name of gynandrous. We think it right to state here, that it is in the altered sense that epigynous is now usually adopted in systematic works. When the torus is conspicuous, and of a fleshy nature, it is often known by the name of disc. To those bodies between the calyx and pistil, unlike either the stamens or petals, of the nature of which Linnaeus was uncertain, he gave the general name of nectary.

Floral Envelopes.

These immediately surround the sexual organs, and are formed of one or more whorls of variously modified leaves. When there are two whorls, the plants are termed dichlamydeae; and the outer is called a calyx, the interior a corolla.

Calyx.

The calyx is usually of a green colour, and foliaceous; each segment is termed a sepal; those like leaves are sometimes articulated at their base, when they are either quite distinct from each other, or cohere in the form of a lid (as in Echinoscleria) during the flowering of the plant. But they are often continuous with the peduncle, and consequently persistent. In such cases they are either distinct, or are united together by their margins. When the sepals are distinct, the calyx is said to be bi-, tri-, or polysepalous, according as there are two, three, or many leaves; and when soldered, it is called gamosepalous, or, by the strict followers of the Linnaean nomenclature, monophyllous; when only slightly united at the base, it is partita (bi-, tri-, quadripartitus, &c.); when united to the middle, it is termed divided (bi-, trifidus, &c.); and when soldered till near the apex, it is called toothed (bi-, tridentatus, &c.). If no teeth be perceptible, it is then entire; and in that case the number of parts must be determined analogically, or by other means. The cohering portion is termed the tube. Some sepals in the same calyx may cohere together in a greater degree than the others, and this gives rise to a bilabiata calyx. In a few genera with articulated sepals, the divisions cohere together, but separate from the tube in the form of a lid or operculum. Sometimes the calyx is reduced to a mere ring round the base of the corolla. In the Valerians this ring is afterwards developed into a pappus, formed of numerous long and fine radiating segments. In many Compositae the margin of the calyx also constitutes a pappus, appearing either in the form of a ring, or bristles, or scales, or rough hairs (pilosus), or feathery hairs (plumosus). The calyx may be free from, or unattached to, the fruit; or the tube may be closely incorporated with it, or adherent (calyx adnatus).

Corolla.

The corolla is for the most part more or less coloured; and it exists in the greater part of the Exogenous plants. Sometimes it is very small, and reduced to the appearance of mere scales, and even in some genera is quite abortive; and when this happens, we must proceed with the greatest caution, and depend much on analogy, so as not to confound those groups of plants in which it ought to be present with those furnished with a perianth, in which a true corolla is always supposed to be absent. The divisions of the corolla are called petals. They are almost always articulated at the base, and consequently fall off; and when this happens at a very early stage, they are said to be caducous. When the petals have no articulation, as in Campanula, they either remain for a long time, or are persistent; or are marcescent, when they wither away without falling off. When the petals are quite distinct from each other, the corolla is polypetalous; or, when more or less united by their margins from the base upwards, monopetalous, an incorrect term, which ought to be exchanged for gamopetalous; and then it may be partite, divided, toothed, or entire. The vine, and the keel (carina) of a peeblossom, or other papilionaceous flowers, exhibit this structure. When the lower part of a petal, as the petiole of leaves, is narrow, and consists of the union of all the vessels that expand and ramify in the upper portion, the contracted part is the claw or unguis; the dilated, the limb or lamina. If the unguis be long, straight, and closely approached to each other, even though distinct, a kind of tube is formed; but, properly speaking, it is only a tube when the claws are united. The orifice of the tube is termed the throat or sinus; and this may be naked (nudus), or furnished with little scales or appendages, called sometimes a crown. The shape of the corolla is frequently of importance in distinguishing natural groups of plants. When all the petals are equal, it is said to be regular; when a monopetalous regular corolla has no tube, but swells out gradually from the base to the summit, it is bell-shaped or campanulate (fig. 54); and urceolate if it is swollen at the base, and contracted at the top; when there is a tube, and when it is narrow below, but dilates upwards, so that the limb is campanulate, the corolla is infundibuliform, or funnel-shaped (fig. 55); it is rotate (fig. 56) or wheel-shaped if the tube be very short, and the limb spreading and nearly plain; hypocrateriform, (fig. 57) when the tube is long, narrow, and cylindrical, and the limb spreading like a star; and tubular, when it is almost entirely composed of a narrow elongated tube, slightly dilated upwards; but this may be viewed as a very slender state of the infundibuliform. When the petals are unequal in size, or cohere unequally, the corolla is irregular; and if such petals unite, we shall have an irregular monopetalous corolla, which is said to be labiate or bilabiata (fig. 58) when the tube is more or less elongated, the throat open and dilated, the limb divided transversely into two parts or lips (labia), the one superior, the other inferior, which lips are subject to various modifications, one of the most curious being where the upper lip is so slightly developed as to appear to be absent, as in Tenerium. A personate (fig. 59, 60) or mask-like corolla is when the tube is more or less elongated, the throat very dilated, but closed up by the approximation of the limb, which has two unequal lips, as in the snapdragon; but it is often very difficult to distinguish between personate and labiate flowers. When the upper part of the tube of the corolla is split down on one side, and becomes flat, it is what is called ligulate (fig. 61), as in the hawkweeds, or exterior flowers of the daisy. A regular polypetalous corolla is said to be rosaceous (Plate CXIII. fig. 62) when composed of three, four, or five, rarely more petals (fig. 62, a), of which the claw is very short, and the lamina diverging from each other, as in the rose. When there are five petals, the unguis of which are elongated, forming a false tube, and concealed within the calyx, the corolla is carophyllate, as in the pinks; and when there are only four petals, with long straight claws (fig. 63, a), and patent lamina, forming as it were a cross, the corolla is cruciform (fig. 63), as in the wallflower; but it is not essential to this last, that the petals be perfectly alike and equal to each other. Of irregular polypetalous corollas, the only one that has received any particular designation is the papilionaceous (fig. 64). Here there are five petals; the upper one is usually larger than the others, and covers them before the flowers expand, and is called the vexillum or standard (fig. 64, a), from its resemblance to a flag; the two lateral ones, like the wings of a butterfly, are the alae or wings (fig. 64, b); and the two lower ones, usually more or less Sexual Organs.

Many of the ancient philosophers were well aware that there was a difference of sexes in plants as well as in animals; and Theophrastus even states, that the fruit of the female palm will not germinate, unless the pollen of the male be shaken over the spathe of the female when both of them are in flower; but it was not till the time of Grew that anything certain was understood on the subject. He was the first who regarded the stamens as the male, and the pistilla as the female organs. Linnæus afterwards improved on Grew's ideas, and has adduced so many proofs from theory, and what is of greater importance, from experiments of a tedious and delicate nature, that none now can experience the smallest doubt. An account of his arguments and experiments, and others of a late date, with the mode in which fecundation is supposed to be accomplished, forms one of the most interesting parts of vegetable physiology.

Stamens or Male Organs.

Each male organ is a stamen; but the whole taken collectively forms the androcarpum, a term that bears the same relation to stamens as a corolla does to petals. These are situated between the petals and pistilla. Although a calyx and corolla be usually present in flowers, yet we have seen that they are not essentially necessary; but no plant can produce seed without the assistance of stamens and pistils, or their modifications. When stamens and pistils occur in the same flower, it is termed perfect or hermaphrodite; but, as sometimes happens by abortion or other causes, the stamens appear in one blossom and the pistilla in another. Again, according as these are on one or on different individuals, the flowers are called monococious or dioecious; and, generally speaking, the flowers are imperfect or diclinous (flores dichenes).

The number of stamens is variable, five or ten being the usual number among the Exogenae, and three or six among the Endogenae; but, on the one hand, these are subject to abortions, and on the other to multiplication. When the last takes place, it is by the addition of one or more rows similar to the first; so that although apparently indeterminate, they are actually a certain multiple of the primitive number.

A stamen consists of a filament (fig. 68, a) and an anther (fig. 68, b). The former is the body, which arises from the torus, and is sometimes cylindrical, or awl-shaped, or prismatical, and is even at times expanded, as if into a scale or petal. It is either articulated or contiguous with the torus. Part of it is often united with the petal, particularly when the petals themselves cohere; and the stamen is then called epipetalous. Its length is generally proportioned to the style, but it is sometimes wholly wanting, presenting a sessile anther. In the same flower the filaments are generally equal in length, and such are called isostemonous, but in many they are unequal. In Geranium and Oxalis, where there are ten stamens, five are larger than the other five, and alternate with them. When there are six stamens, of which four are larger than the other two, as in the cabbage, mustard, and the other Cruciferae, they are called tetradynamous; and where there are four, of which two are longer than the other two, they are didymous, but here there is usually the rudiment of a fifth stamen, dissimilar from all the others. The direction of the filaments is usually straight, but they are in some plants bent inwards, in others outwards. In Parietaria (the pellitory of the wall) they are reflexed; for here the filament is bent backwards in such a way that the upper half lies along the lower, and between it and the perigonium. When the filament is too slender and weak to support the... Glossology. weight of the anther, and hangs down, it is pendent; when it bends towards the lower part of the flower, it is decumbent or declinate; and when to the upper part, ascendent.

The filaments are usually free, or isolated from each other; but they are sometimes united more or less upwards from their base into a column or androphore. When there is one androphore or bundle of filaments, the stamens are monadelphous; when two androphores, diadelphous; and when several androphores, polyadelphous.

Anther. The anther is a kind of bag borne by the filament, and corresponds to the lamina of a leaf. It is either sessile, when there happens to be no filament, or it is placed at the top of the filament in three ways: it may be attached by the middle of its back to the slender apex of the filament, and is then oscillating or versatile (fig. 73); or it is attached by its base to the top of the filament, with which it then seems continuous, and is then erect (fig. 69); or it adheres to the filament by its back, and is then adnate or adherent, in which case the filament is often prolonged into an appendage. When adherent to the inside of the filament, it is said to be introrse, and to the outside extrorse. Each bag or cell of the anther is called a lobe; and the solid substance that connects them, and which in fact corresponds to the midrib of the leaf, is the connectiveum (fig. 69, a). Usually the connectiveum is very small and inconspicuous, but in some plants it is prolonged into an appendage, that may be confounded with an elongation of the filament; in others it is prolonged below, as in some heaths, into an awn or crest; in a few it is so broad that the bags of the anther are at a considerable distance from each other (fig. 70). Usually each anther has two lobes; but in a few plants there is only one, and this may happen either from some natural conformation of the plant (and only when the anther is erect), but more generally from the accidental abortion of one of the lobes (and then particularly when the lobes are distant), or by the filament happening to be split, each half bearing a lobe, and representing a distinct stamen. The reverse also happens, so that each anther may appear to consist of four lobes; but this arises either from each lobe being divided into two cells, by the back of the lobe being folded inwards; or it has really four, six, or more lobes (as in some willows), caused by the adhesion of two, three, or more stamens into one. The lobes or cells of the anthers open in different ways, by what is termed the line of dehiscence. This usually indicates the margins of the lamina of the leaf out of which the anther is formed, and therefore the most frequent position of this line is longitudinally along the middle of each lobe (fig. 71), in which case the anthers are bitocular or bitrose. When this line does not open during its whole length, but only above or below, exhibiting two pores, as in the heaths, the anther is styled biporose (fig. 68); or when there is only one lobe, it is called one-pored (pore simplex). Very rarely, as in the lavender, the anther dehisces transversely; but the most singular case is when it opens by valves, as in the barberry and the laurels (fig. 72), that are free below, and hinged as it were by their upper edge. The anther has various shapes; the principal are globular when the two lobes form one globe, didymous when each of the two lobes are globose; the terms linear, sagittate, cordate, reniform, &c., are also to be applied to it in the same way as to leaves of plants. When the filaments are united, the anthers may be so likewise, as in salix monandra; or they may be free. But although the filaments may be free, the anthers may be united to each other by the margins, as in the Compositae, and such are then called synangemones. In Stapelia, where the loculi or cells of the anther are at a distance from each other, each coheres with the locus of the neighbouring anther.

An anther contains and frequently emits a matter call-

ed pollen, the use of which is to give life to the ovule or Glasselos young seed. The grains of pollen seem to arise from the extremities of the veins which are found in the leaf that constitutes the anther, and are probably formed from the spiral vessels. When the grains of pollen burst, they again discharge a multitude of very minute particles, called molecules or granules. When the grains of pollen easily detach from each other, they are said to be pulverulent, and then they may be either perfectly smooth without any viscous coating, or they may be viscous. Sometimes the viscosity is not at once perceptible, but may be traced by means of papillae or small eminences on the surface, which are in fact secretory organs, giving rise to the viscous surface. The nature of these grains of pollen seems constant in each family of plants; and even the shape of these grains is sometimes of consequence in distinguishing natural tribes. In the Asclepiadaceae and Orchidaceae the grains are not pulverulent. Instead of separating readily, all the pollen contained in one cell or bag coheres into what is then termed a pollen-mass; or when each of those are divided into two or four portions, each is sometimes called a massule. When in the Orchidaceae these pollen masses are formed of grains united together by means of an elastic tissue, they are said to be sectile (as in Orchis); but in Epipactis and others they are granulose or farinaceous; and in Corallorhiza and Malaxis, &c., they are of a solid compact substance.

Pistils or Female Organs.

The whole female organs in a flower, taken collectively, have been named gynoecium. This may consist of one or more pistilla, or distinct portions. Thus, in the primrose there is truly one, in Ranunculus many pistilla. The female parts being, like the stamens, petals, and sepals, formed of modified leaves, each pistillum may arise either from one such leaf or from the combination of several. These component parts are called carpels, and are placed in the centre of the flower. They may be arranged, 1st, round a real axis or column, which is the abortive prolongation of the pedicel, and are united to it by their inner angle; this is evident in Malva and Lavatera, and in Euphorbia. 2d, They may be verticillate round the central column, but hanging from its summit, and consequently only attached to it by the apex of the inner angle, as in Geraniaceae. 3d, They may be verticillate round the summit of the axis, but erect, and only adhering by their inner angle at its base; and then the axis may be extremely short, as in Sedum or Aeonium, or it may be slightly prolonged, as in some rutaceae. 4th, The carpels may be placed in a spike round the central column, as in the magnolias and tulip-tree, and some ranunculusses. 5th, But if the column be very short and round, the carpels, instead of forming a spike, will form a head round the column, as in the strawberry, where the column is fleshy. 6th, If the exterior portion of the axis be prolonged along the inner surface of the calyx, while the central part is not, we shall have a hollow cup, in the interior of which the carpels are seated, as in the genus Rosa or rose; and here the expansion of the axis is united to the tube of the calyx by means of the torus. All plants in their primitive state seem to have several carpels in each flower, but they may be reduced to a solitary one by abortion.

Each carpel (fig. 74) may be viewed as a folded leaf, of Carpel which the petiole seldom appears; but when it does it is called a thecophore, or support to the fruit. The ovules or young seeds arise from the extremities of the veins, and therefore are usually attached near to the margins of the leaf, or, as it is folded, to both sides of the inner angle of the carpel; and the parts to which they are fixed are called the placenta. The ovules, like the pollen of an anther- Homology cannot probably be formed without the assistance of spiral vessels, and therefore are not to be looked for in the stems, which are destitute of these elementary organs. The portion above the theca, containing the ovules, is the ovarium (fig. 74, a). But the summits of the placentas are prolonged into two thread-like bodies, sometimes long, and sometimes very short. These are usually combined into one, which is then named the style (fig. 74, b); and its glandular apex, fitted for the absorption of the vivifying part of the pollen, is the stigma (fig. 74, c).

The carpels show a still greater tendency to unite with each other than even the exterior parts of the flower, though often this union seems to take place in a very slight degree. In Stapelia they appear to cohere only by the stigmas; in Asclepias by the stigmas and styles; in some by the ovaries alone, in others by the ovaries and styles; but the most complete is by the ovaries, styles, and stigmas. When the styles are united there is usually said to be but one, although the pistil ought more properly to be then called gamostyle; and in the same way, when the ovaries are united, there is still said to be one ovary, called by Linnaeus a germen, consisting of a number of cells (loculi), although each of the cells is in fact an ovary.

The number of stigmas is determined by that of the carpels and styles, or their divisions; so that in a compound ovarium, when we speak of one stigma, we actually mean several united into one mass (fig. 75, c), as in the primrose. It is sessile when there is no apparent style, terminal when placed on the top of the style or ovarium, and lateral when attached to the sides of these organs. In substance it may be fleshy, glandular, or membranaceous, and even petaloid when it resembles a petal, as in the iris. Its form needs no illustration further than, when several are only partially combined, they are said to be bifid, trifid, or multifid, as if there were actually a simple one variously divided. Its surface is either smooth or pubescent; in some plants it is pellucidiform (fig. 76), or of hairs forming a small tuft; in others, as in Anemone, Clematis, and many grasses, it is plumose (fig. 77), or furnished with hairs arranged in a line on both sides, like the vanes of a feather; and is aspergilliform (fig. 78) when the hairs are placed in many whorls around the stigma, like a bottle-brush. In a few orders, as Goodenovceae, Scrophulariaceae, and Brunoniaceae, the stigma is enveloped in a peculiar membranous appendage, called an indusium.

The style is in common language said to be simple (simplex), or single (unicune), either when it is the style to one carpel (fig. 74, b), or is formed by the union of several into one body (fig. 75, b), and is divided when the component parts are more or less adherent. But a style in its simplest state, being actually formed by the prolongation of the two placentae of a carpel, is even then a compound body. What are said to be two styles in the grasses (fig. 78) is thus in reality but one divided style.

The two stigmas in Compositae indicate the same structure, as well as those of many Euphorbiaceae, where the divisions of the style and stigmas are double those of the carpels. The style may be included within the flower (inclusa), or protruded beyond it (exserta). It is usually terminal in a compound ovarium; and lateral, or basilar (from the base), in a simple one. In some plants with a deeply lobed ovarium, the individual ovaries are attached to each other almost only by their bases; and hence the united style, springing from the point of union, forms as it were a continuation of the axis. The style is of various shapes, but the most singular is when it is petaloid, as in Glossogyne, the iris. It may be straight, or declinate, or ascending.

When no union takes place among the carpels, the ovarium is termed apocarpous, as in Ranunculus; and when there is an adherence, so that a compound ovarium is formed, it is called syncarpous (fig. 75). In the former case there may be one or more pistillae, according to the number of carpella; in the latter only one. The ovary being formed of the lamina of the leaf, the edges of which may be sometimes rolled inwards, it is evident that we may have each carpel of two cells, as in Astragalus; but the division is very seldom perfect. When the ovaria are united into a compound or syncarpous ovarium, the sides of the component leaves or ovaria (which sides are then termed dissepiments) may be evanescent, in which case we have a unicellular ovarium with a central placenta (fig. 79); and when the leaves forming the ovaria are scarcely folded, but nearly plane, the placentiferous margins touching respectively the margins of the next ovaria, an unicellular syncarpous ovarium is produced (fig. 80), having the placenta parietal, or exhibiting longitudinal lines on the interior surface. In a compound ovarium, when the margin of the folded carpel is rolled inwards a little way, so that each ovarium is almost bilocular, it is evident that the placentas must be situated nearly in the centre of each division of the fruit, in which case the two placentae in each cell may either unite closely together, as in Kalonia or Rhododendron (fig. 81); or may diverge from each other (fig. 82), as in the gourds. An apocarpous ovarium may be known from a syncarpous one, when there is no abortion, by the number and position of the placentae. Although in every plant a carpel is present, yet in Cycadaceae and Coniferae, where there is neither style nor stigma, the apocarpous ovarium is plane or spread open like a scale, leaving the naked ovule, on its inner surface, exposed without any covering to the pollen; and even, though very rarely, the carpel may be so modified that the ovary is abortive, and nothing is visible but the naked ovule.

The ovary is free or superior when it contracts no adherence with the calyx; or inferior, and then it is syncarpous, and the tube of the calyx adheres with it. But the individual ovaria may be placed inside the tube of the calyx without being united with a syncarpous ovarium, as in the roses, when they are said to be parietal. Between an inferior ovary and ovaries parietal it is sometimes difficult to draw a distinction; for when there is only one series of the latter, they may project so far towards the axis of the fruit as nearly to meet each other, and thus resemble a syncarpous ovary. But the difficulty is diminished by considering that, in a true inferior ovarium, each carpel must so touch the calyx as to represent a syncarpous ovarium seated within the tube. Each carpel must therefore unite laterally with its contiguous one, and at the same time all must be united at the axis of the ovarium, so that there must result from the union one compound pistil. A compound pistil ought thus to indicate an inferior ovary. On the contrary, a separation of pistillae will always be accompanied with parietal ovaries (as in the rose and apple); and to these rules there is, we believe, no deviation. An apparent one is in that section of the genus Rosa called stytyle, as in the Ayrshire rose, and another in Crataegus monogyna, in both of which the styles unite into one; but even here a slight dissection of the ovarium will show that the individual carpels are not strictly united at their inner margins, and consequently that the ovaria are

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1 In this tribe the sides of the carpel or leaf connecting the exterior with the centre of the compound ovarium are extremely thin and inconspicuous, while the inflexed margins are remarkably well defined; hence Serigne and De Candolle have been erroneously induced to suppose that here the midrib of the constituent leaf is, by some inexplicable means, placed in the centre of the ovarium. Glossology-parietal, and the compound ovary apocarpous, or of more than one pistillum.

PL CXIII. The partially adherent calyx of many saxifragas has led some botanists to say of them that the ovarium is half inferior (semi-superum); but from their being two pistilla, it is apocarpous. In Umbelliferae there is but one pistil, although two styles; and the ovary is syncarpous and inferior. To avoid confusion it might be better to adopt the terms of syncarpous and apocarpous ovaria, and adherent or free calyx; and a combination of these will indicate the structure of the fruit.

Each simple ovarium is more or less compressed; but the usual shape of a syncarpous one is ovoid. It is, however, sometimes elongated. In most plants it is entire, but in the borage tribe and labiate plants it is deeply lobed (Pl. CXIV. fig. 118).

Ovulum.

The ovulum, as we have already explained, is the body borne by the placenta, and is destined to become a seed after impregnation. The position of the ovula is of great importance in determining natural affinities. When it is fixed by its base to the bottom of one of the cells of the ovarium, of which it takes the direction, it is said to be erect, or if it hangs from the summit of the cell it is inverted; but if the ovulum is attached to the middle portion of the placenta, it may have an upright direction, and is called ascendant, or point downwards, and is then suspended (appensum); or if it appears attached by its middle, so that one half points upwards and the other half towards the base of the cell, it is called pericarpal. By most botanists, however, the erect and ascendant ovula are confounded under one name, and the inverted and suspended are known by the term pendulous. Either of these may at times resemble the other by an accidental inversion, when the ovule is said to be resupinate. The ovulum is either sessile, or on a stalk called a funiculus or podosperm (fig. 83, a), and in either case the point by which the connection is formed is usually termed the base of the ovulum, and its other extremity the apex. The ovulum consists of a nucleus and two external coats; the outer of which (fig. 83, 84, and 85, each at the letter b) is called the testa or primine sac; and the inner, the internal membrane, or secundine sac, or the tegmen (fig. eed.e). The base of the nucleus (fig. card.d) is always incorporated with the base of the internal membrane, and their common base is attached at some points to the testa. The junction of the three forms the chalaza. The chalaza is sometimes at the base of the testa, but is more frequently at the apex of that external covering, so that the apices of the nucleus and tegmen, though in some plants pointing to the apex of the testa, are more usually directed to its base. Close to the apex of the nucleus, and consequently at the opposite extremity from the chalaza, a small aperture or foramen (fig. eed.e) is to be observed in both the primine and secundine sacs. This foramen (called by Mirbel exostome in the primine, and endostome in the secundine) must always be found near the base of the ovulum when the apex of the nucleus points towards that base, and at the summit of the ovulum when the apex of the nucleus points to that part; and consequently the situation of this foramen will at once indicate the internal structure of the ovulum. And this is of the greatest importance, as the future embryo is now well ascertained to be so placed in the nucleus that the radicle points directly to these orifices, as do the cotyledons to the chalaza; and a means is thus given of discovering even in the ovulum the future internal arrangement of the seed. In what we have said, we have presumed the testa, tegmen, and nucleus, to be straight; but in some plants all or some of these are more or less bent or curved, in which case we may have the apex of the nucleus directed towards its base, as in the Cruciferae and Chenopodiaceae, and even the grasses; or towards the side of the testa, as in the Leguminosae.

The testa is usually entire, except at the foramen, but in two known genera, Banksia and Dryandra, it opens longitudinally, leaving the tegmen exposed. The surfaces of the testas of the two collateral ovules in these plants then unite, putting on the appearance of the dissepiment of a capsule; and the two cohering ovula seem to be as one bilocular ovulum. By this means the internal membrane or tegmen becomes the external envelope of the seed.

When the apex of the nucleus is contiguous to the base of the ovulum, a connection takes place between the base of the ovulum and the base of the nucleus, by a bundle of vessels (fig. 85, f) called a raphe. This raphe is almost always on the side of the ovule next the placenta, and even the apparent exceptions to this rule tend to confirm it. Thus in the tribe to which Eucalyptus belongs, the ovules are erect, yet in some species of that genus they

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1 Brown and Mirbel term the chalaza the base, and the foramen the apex of the ovule, without regard to the point of attachment of the ovule to the placenta, which must be attended to in studying their works.

2 Mirbel, as we have already stated, considers the base of the ovulum and seed as at the chalaza, and he divides seeds into orthotropous, anatropous, and campylotropous. The first are attached to the ovary by their base, having a perfectly regular form, and the axis is rectilinear. The campylotropous are also fixed to the ovary by their base, but their form is irregular, and their axis is curved, so that the two extremities meet. The anatropous, like the orthotropous, have a rectilinear axis, but they are resupinate on their funiculus, to which they adhere longitudinally; and by means of which they are attached to the ovarium at a point near their apex. These variations are explained by Mirbel, by what he denominates the states of development, or the force of expansion, or of inertness, or of contraction of the different parts of the ovulum; and he has endeavoured to show how these causes, acting either together or independently, alter or preserve the regularity of the primitive shape. Every ovulum, according to him, has at first a regular form, and the chalaza close to the hilum or funiculus; so that if the force of development be equal at all points, the regularity of shape must be preserved, but if it be greater on one side than on the other, an irregularity must ensue. In this way an equilibrium of forces must have taken place in any orthotropous seed, but not in the anatropous or campylotropous ones. When an ovulum tends to become anatropous, the chalaza or the inner extremity of the funiculus is pushed forward in a slightly oblique direction, and invades the ovulum, so that its base is placed where its summit formerly was, and vice versa; a kind of resupination which is stated by Mirbel to take place in the course of development, and which he has been able to trace through the successive changes. By this means the vessels of the funiculus become elongated in proportion to the length of the axis of the ovulum; and such prolongations, united laterally to the primine sac, and extending from the exostome to the chalaza, is what he terms the raphe. These characters distinguish the ovule destined to become in maturity a campylotropous seed: the indissoluble union of the hilum and the chalaza; the great force of development of one of the sides of the ovule; and the inertness or even contraction of the opposite side, which remains stationary, or even diminishes, while the other elongates. Had this last side been free in its development, it would have elongated in a straight line; but it is constrained by the inertness or contraction of the opposite one, and can therefore only increase by turning round the other as a centre. From this arises that annular form which most of the campylotropous seeds possess; and hence also, in all curved seeds, the chalaza ought to be constantly opposite to the hilum, and the foramen at the opposite extremity. Although all seeds may be reduced to these three types, yet by their development being stopped before the ovulum attains to the perfection of the type, and from similar results arising sometimes from different causes, many anomalies may be expected. Several have been pointed out by Mirbel himself. Thus, in the pea, the young ovule exhibits the anatropous form; but afterwards the raphe remains stationary, while the opposite side expands, and the seed appears campylotropous, but with a raphe. Fecundation having taken place, the floral envelopes usually fade away, the stamens disappear, and the pistil begins to increase in size and become the fruit. Although the style and stigma, having fulfilled their functions, are now nearly obliterated, the fruit ought always to show some traces of them on its surface, whenever they were seen on the ovary. In Cycadeae and Coniferae, where the ovulum is exposed to the immediate action of the pollen, there is neither style nor stigma upon the scale or open ovary, so neither is there on the fruit, indicating the existence of naked seeds; but the grains of corn and wheat and other grasses, having the remains of a style, are true fruits; the supposed naked seeds of the borage tribe and labiatae are for the same reason parts of a fruit. As the pistillum advances towards maturity, many alterations take place, in consequence of abortion, non-development, obliteration, or even union of parts. Thus a compound pistil having a compound or syncarpous ovary, may have a fruit of but one cell, as the hazel-nut; or a solitary pistil may, by the involution and divarication of its placentas, change into a fruit with several cells; or the placenta itself may expand horizontally, dividing one true cell into several spurious ones. In all cases, however, the contrasting the structure of the pistil with that of the fruit will materially aid us in our investigations.

The base of the fruit (fig. 86, a) is the part where it is joined to the peduncle. The apex (fig. 86, b) is where the remains of the style are found.

The portion of the pistil called the ovarium is in the ripe fruit termed the pericarp; it is sometimes extremely thin, as in the grasses, the borage tribe, the Compositae, &c., but is often extremely thick, and even fleshy. As the leaf of a plant has an upper and under surface, and an intermediate parenchyma in which the nerves are placed, so the pericarp consists likewise of three portions: the outer coating, which often determines the form of the fruit, called the epicarp (fig. 87, b); the inner lining or the endocarp (fig. 87, d); and the parenchymatous or fleshy substance between these (fig. 87, c), termed the sarcocarp or mesocarp. When the ovary is inferior, or united with the tube of the calyx, as in the apple, the epicarp becomes confounded with the tube (fig. 87, a), and then the sarcocarp may be readily taken for the parenchyma of the calyx; but in peaches and other fleshy fruits not adherent to the calyx, it is the sarcocarp that constitutes the flesh. The endocarp is usually a mere membrane, but it sometimes is incorporated with a portion of the sarcocarp; and when this portion becomes hard and osseous, it constitutes what is called a putamen (when it contains but one seed), or nucleus nuclea (when they contain several seeds). As an ovary may be apocarpous or syncarpous, so also may be the pericarp. It is therefore said to be unilocular (fig. 104 and 105) when there is one cell, and bi-, tri- (fig. 88), or multilocular, according to the number of cells. These loculi or cells are separated from each other by dissepiments. By reverting to what has been said about the ovarium, we shall easily perceive that true dissepiments can only be formed in one way. Two contiguous portions of the endocarp are projected into the interior of the pericarp, and are agglutinated together by the parenchyma of the primary leaf; now the sarcocarp.

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Mirbel takes rather a different view of the subject: he considers the nucleus as a mere envelope, terms it the testes, and states that it includes two others—the quartine, which appears to be attached to the summit of the cavity, and that containing the quintine, or embryonic sac, the last envelope, and adhering at both extremities to the quartine. But each of these parts, if they do exist, has not been seen in every ovule; and in those in which they have been observed, they are not all visible at one time, but in succession; when the first is most evident, the last are merely rudimentary; and when the latter are developed, the former are scarcely distinguishable. Mirbel even points out five distinct periods of development. The dissepiment is thus always of two membranes, which must contain between them vessels and nerves; and these again will point out the former junction of the two membranes, even although, by the sarcocarp drying up, they should have lost their adherence, and have separated from each other. Dissepiments may be complete when they extend from the base of the epicarp to its apex, and incomplete when they permit two contiguous cells to communicate with each other. In the thorn-apple (Datura stramonium) there appears at first sight to be four dissepiments, two complete and two incomplete; but in reality in this plant there are only two, curiously modified.

The axis of the fruit is that round which the constituting carpels are placed. It is sometimes not apparent. When it actually exists it is usually termed a columnella, as in Euphorbia, Lavatera, &c.; but when two mericarps are united together it is called the commissura (fig. 92).

As seeds are inclosed in the pericarp, it is essentially necessary that they, after maturity, have the means of escaping. Sometimes, however, the pericarp does not open naturally, but is either split by the process of germination, or rots away by the action of the soil or of the atmosphere. It is then said to be indehiscent, as in the grasses, Compositae, &c. But usually it splits open, and is then dehiscent; and the pieces into which it divides are termed valves. In some the dehiscence is incomplete, as in Antirrhinum (fig. 89), where it is indicated by two pores at the apex, and in many Caryophyllaceae (fig. 90), where the valves only separate at the apex into teeth. The pericarp is said to be uni-, bi-, or multivalved, as there are one, two, or many valves. When a fruit is in its simplest state, or formed by the transformation of one carpellary leaf (Plate CXIV., fig. 104), there may be two sutures or lines by which it may open. The one is (a) where the margins of the leaf or the placenta meet, and this is called the central suture; the other, or the dorsal suture (b), is at the part corresponding to the midrib of the leaf. But, in a compound fruit, an opening may also take place at the junction of any two carpels; and from these considerations the various kinds of dehiscence may be explained. If the line of opening corresponds with the junction of the carpels, the dehiscence is septicidal (fig. 91); so that where there are dissepiments, these are divided each into two constituent membranes, and the cells remain closed at the back; or the valves were formerly said to be alternate with the dissepiments, or to have their margins turned inwards. If the opening is by the dorsal suture of each carpel, the dehiscence is loculicidal (fig. 86 and 88); so that here the dissepiments do not divide into two portions, but the cells are opened at the back, or the dissepiments were said to be opposite to the valves, or the valves to bear septa in their middle. In some plants the cells remain closed, and separate in that state from the axis, which is then an extension of the peduncle (fig. 92). In others the placentas separate from the dissepiments and adhere to the axis, while the cells open, and, with the dissepiments, separate from it (fig. 93). When the dissepiments adhere to the axis, but separate from the back of the valves or carpels, the dehiscence is said to be septifrage (fig. 94). When a dehiscence, instead of being vertical or longitudinal, takes place across the cells, it is called transverse (fig. 95), as Anagallis.

The shape of the pericarp may be spherical, or ovate, or leathery (like a lens), or prismatic, which terms are easily understood. It may be acute, or obtuse, or lobed. When the fruit is inferior it is often crowned by the teeth of the calyx; and these teeth in many Compositae, as we have already explained, are represented by a series of hairs called a pappus, which is either (fig. 96) pilose, when each hair is simple, or plumose (fig. 97), when each hair presents on each side a series of finer hairs, arranged like the wings of a feather. Glossology. In Valeriana (fig. 98) the limb of the calyx is at first rolled up so as to form a circular ring on the top of the ovary, but afterwards (fig. 99) expands and elongates, and constitutes a true plumose pappus. When the tube of the calyx is filled by the seed, the pappus is said to be sessile (fig. 97); but when it is much attenuated at the apex beyond the seed, a kind of stalk or stipes is formed to the pappus, and it is termed stipitate (fig. 96), but between these there are some states that tend to weaken these as characters.

Fruits have been classified in several ways, and have received various designations. From what we have already said of the ovarium, we trust the following division may be easily understood. A fruit is either simple, multiple, compound, or aggregated.

It is simple when it is the maturation of a single carpellary leaf. Fruits of this class may be either indehiscent or dehiscent. Of the former is 1. the caryopsis, where the pericarp is very thin and membranous, and so closely united to the solitary seed as not to be distinguished as a separate body, as in the wheat and barley (Plate CXIII., fig. 100); 2. an utricule is similar to the caryopsis, the pericarp being membranous, but it has no adherence with the seed; 3. an acheneum is also one-seeded, but here (fig. 101) the pericarp is hard and bony, as well as distinct from the proper covering of the seed, as in the Compositae (these three are often confounded); 4. a samara (fig. 102) is a coriaceous, membranous, very compressed, few-seeded, indehiscent fruit, that is often prolonged laterally or at the apex into wings or appendages, but this kind does not perhaps exist in nature in an uncombined state; 5. a drupe is a fleshy nut inclosing a putamen, as the cherry and peach; 6. a nut (nux), in its strictest sense, as now adopted by Richard and De Candolle, differs slightly from a drupe; it contains a putamen, but the sarcocarp (then called nucum) is coriaceous instead of being fleshy. The dry dehiscent fruits are, 7. the follicle (fig. 103), or a carpel dehiscing by the ventral, and having no dorsal suture; 8. the legume (fig. 104), having both ventral and dorsal sutures, by either of which, or by both or neither, it may dehisce; rarely the sides fall off, leaving nothing but the sutures, which then form a kind of frame called replum. The legume is, strictly speaking, unilocular, but in some plants appears bilocular, from an inflexion of the ventral suture (fig. 105). In some instances it is separated into several parts by horizontal partitions (fig. 106) arising out of the placenta, or by contractions of the legume itself, as in Hippocrepis or Scorpirus (fig. 107), at which it falls into pieces, when it is said to be lomentaceous.

A fruit is multiple when the ovarium is apocarpous. It has more than one style, and is formed of more than one carpellary leaf in the same flower. The carpels may be either at a distance from each other or slightly connected, but the endocarp does not separate from the epidermis to form dissepiments. Few individual names have been given to this kind, botanists having usually contented themselves with saying that it is composed of achenia, drupes, &c., according to the structure of each individual carpel. When these are arranged upon or round a real or imaginary axis, the fruit has been by some called, 9. clavion; the strawberry (fig. 108), bramble, ranunculus, anona, and peony, are examples. 10. The pomum or melonoida also belongs to this class; here the fruit is crowned by the teeth of the calyx, and is formed of several parietal carpella attached to the interior of the tube by the intervention of a usually thick and fleshy expansion of the torus. Of this there are three varieties. 1st, When the numerous achenia are attached to the slightly fleshy calyx, the fruit is a hip or cynorrhodon (fig. 109), as the rose. 2d, When the calyx of the hip does not become Botany.

The third variety is the apple or pomum (Plate CXIII, fig. 87), in which there is but one longitudinal series of carpels attached to a very fleshy calyx, and so enlarged as to appear to meet in the axis of the fruit. A pomum, then, at first sight seems to be the maturation of one inferior plurilocular, instead of several parietal ovaria.

A compound fruit is derived from a syncarpous ovary, and is formed by the union of several carpellary leaves. In Rumex, and other plants with apocarpous ovaries, more than one series of carpells are often matured. This, however, happens rarely among the syncarpous, but it sometimes occurs; thus, in Nicotiana multivialis, where the fruit is a capsule, two rows of carpellary leaves are united into one pistillum. 11. A capsule (Plate CXIII, fig. 89 and 90) is a dry, dehiscent pericarp, usually many-celled; but may, by the placenta being parietal, or by the disappearance of the dissepiments, be occasionally one-celled. 12. When a capsule opens transversely, it is called a pyxidium (fig. 95). 13. When a capsule bursts into achene, it is termed a di-, tri-, or polakenium. 14. When the tube of the calyx adheres to one of this last kind, the fruit is called cremocarpium (fig. 92), as in the Umbelliferae; and each of the two constituent parts (a) a mericarpium. 15. When a capsule is composed of cocci, or cells that open elastically by a membranous spring placed at the bottom, it sometimes has got the name of elaterium or regma, as in Euphorbia. 16. A silique when long and narrow (fig. 110), and silicula when so short as to be almost as broad as long (fig. 111), is a dry pericarp formed of four carpels, the placenta of which are parietal; moreover, the stigmas and placentas of an opposite pair of these carpels are abortive, so that the carpels themselves represent valves, while the two other intermediate carpels are contracted, and project, from the inner side of each placenta, a membrane, which unites at the centre of the fruit to the corresponding opposite membrane, the four membranes being ultimately united into one dissepimental membranous expansion. In common language, then, a silique or silicula may be defined to be a dry, dehiscent, two-valved fruit, in which the seeds are attached to placentae situated at the sutures of the valves, and which is usually divided into two loculi or cells by a false dissepiment or prolongation of the placenta, that is parallel to the valves. After the valves have fallen, the placentae often remain, with or without the dissepiment or septum, in the form of a replum. 17. When two samarae are applied to each other so closely that there appears but one (fig. 115), as in the ash and elm (the compound nature of the fruit, however, being still evident from the double stigma even when one of the cells is abortive), the fruit is still commonly called a samara; but in Acer, where the constituent parts are readily distinguished, the fruit is said to consist of two seamaroid carpels. 18. A carcelurus (fig. 116) is dry and indehiscent, with several cells and seeds, as the lime tree. 19. A gland is a dry, bony, indehiscent, one-celled and one-seeded fruit, but always the result of an ovary with several cells and several seeds. The pericarp unites closely to the seed, and is inclosed more or less in a sort of involucrem. This term is sometimes restricted to the case where the involucrem or cup is coriaceous and scaly, as in the acorn; and when it is foliaceous, as in the hazel, it is called a nucula. Many botanists apply to both of these the name nut or nue. When the involucrem is entirely wanting, and the fruit is borne on a fleshy support, it has been termed a xylocladium (fig. 117), as in the cashew-nut. 20. A microbasis (fig. 118) applies to the fruit of the Labiatea and Boraginaceae. Here it is tetraspermous or four-sided, and appears to be quadrilocular; and each division, resembling a distinct achene, is placed around the slender base of the style; in reality, however, it is a bilocular fruit, each cell being divided by a spurious dissepiment into two, each one seeded, that in general easily separate from each other. 21. In a sarcobase (fig. 119) the ovary is syncarpous, or of one pistillum; but all the carpels appear distinct, and are borne on the fleshy base of the compound style, as in the Ochnaceae. 22. A nuculanium is a fleshy fruit, not adherent to the tube of the calyx, and including several distinct putamen or nucules. 23. An ostocarpium is a superior fleshy fruit, with several cells, the sarcocarp being bony. 24. The balanosta is a somewhat coriaceous, plurilocular, polyspermous, inferior fruit, adherent with the calyx and crowned with its teeth, as in the pomegranate and myrtle. 25. A berry (bacca) is a succulent fruit, with a membranous pericarp, the seeds of which lose their adhesion when ripe, and lie loose in pulp, as the gooseberry or grape (fig. 120). 26. The orange or hesperidium is a multilocular succulent fruit, similar to a berry, but having the epicarp, sarcocarp, and endocarp well defined, and forming a leathery pericarp. The loculi or cells are filled with pulpy bags or vesicles, which are mere cellular extensions of the sides of the carpella. 27. A pepo or peponida is a fleshy inferior fruit, either indehiscent or bursting irregularly, and consisting of about three carpels, each of which is divided into two loculi by its placentiferous margin (Plate CXIII, fig. 82) being so introflexed as to reach the dorsal suture. The sides of the carpel, and even sometimes the introflexed portion, usually disappear in the ripe fruit; so that at first sight it would be said to be, and has been so described, a one-celled, fleshy, indehiscent fruit, with parietal placentas that send out sometimes false dissepiments towards the axis (fig. 121), as the cucumber and gourd. We do not agree with Richard in calling the fruit of the Nymphaea or Nuphar a peponida. In these there is in fact an apocarpus ovarium (fig. 122), each carpel being merely attached by its back to an expansion of the torus, which soon decays, leaving the carpels distinct from each other. The torus also surrounding the styles and the stigmas, makes the whole assume the false appearance of one pistillum; and that part of each carpel which is directed towards the axis of the fruit is the placentae, and not a dissepiment. There is, therefore, little or no difference between the Nymphaeaceae and Nelumboaceae, except that the carpels of the latter are monospermous. The fruit of Hydrocharitaceae resembles in some degree a peponida; it is one-celled, and the placentas are truly parietal, but project from the false dissepiments towards the axis, appearing sometimes as if a many-celled fruit.

Aggregated fruits are formed out of several flowers. 28. An amenium or catkin exists in those plants to which there is no floral envelope; but in place of it there is a membranous bractea situated below each pistillum, as in the Salix or willow. 29. When the bractea of an amenium becomes extremely small, and the carpellary leaf is a large indurated scale, open at all periods of its growth, and containing naked seeds, we have a cone or strobilus (fig. 129), as in the pine tribe; and when this is much re-

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1 If \( c', c', c' \), etc., in fig. 112, be four carpels with parietal placentae and ovules (\( v', v', v', v' \)), and if \( c', c', c' \), etc., be the stigmas to each, then if \( c', c', c' \), etc., be abortive or disappear, we shall have the appearance in fig. 113; and if, in addition, the placentae \( b, b, b, b \), project each a membrane into the centre of the fruit, when these membranes unite we shall have the section of a silique or silicula, as in fig. 114. The fruit is formed of two parts, the pericarp and the seed. What we have already gone over belongs to the former; we now proceed to the latter.

The seed is that part of a perfect fruit which is found in the internal part of the pericarp, attached to the placenta, or to its process, the funiculus. Every seed arises from a fecundated ovule, and therefore a naked seed can only be said to exist in those rare cases in which we have found a naked ovulum. Its essential character is to include an organized body, which, under favourable circumstances, is developed, and becomes a plant similar to that from which the seed was obtained. This body is called the embryo.

The position of the seed is of equal importance with that of the ovule; but as the terms are the same, we will not here repeat them.

In the ripe seed, what was the base of the ovulum becomes the base of the seed, and is called the hilum or umbilicus; the expansion of the raphe at the base of the nucleus becomes the chalaza; and the foramen is then called the micropyle (fig. 129, a). The testa (fig. 130, a) or primine sac sometimes disappears, and in others becomes thick; the tegmen (fig. 130, b) becomes usually incorporated with the testa, although it also in some plants disappears, and the two are generally known under the name of episperm. De Candolle has, without considering the ovule, but only regarding the ripe seed, followed Richard, and viewed the episperm as but one coat, the outer surface of which he has termed the spermoderm, the inner, the endopelura, and the intermediate portion, chiefly constituted by the spreading vessels of the raphe, the mesosperm. But the terms testa, tegmen, and raphe, are much less exceptionable, as they exhibit a relation to the structure of the ovulum. In some plants, as we have already said, the testa is fleshy; in others it is attenuated (fig. 128) into a long process, both of which may be mistaken for an arillus if proper attention be not paid. In the cotton-plant the whole surface is covered with hair-like expansions, when the seed is said to be wrapt in wool; or such hairs may be merely placed at one or both ends, when they constitute a coma. In some plants there are tumours on the testa, near the hilum, or at its opposite end, called striphiola or cornucule (fig. 131), the precise nature of which is unknown; but in some instances they appear to be dilatations of the chalaza, and in other cases they seem caused by a diseased state of the lips of the foramen or micropyle.

After impregnation, the nucleus undergoes great changes. The embryonic sac increases rapidly in every way, and often pushes back the cellular tissue or parenchyma of the nucleus, until this latter is reduced to a thin pellicle or membrane, and is ultimately filled with nothing but the embryo; in which case the membrane or sac itself either disappears entirely, or becomes incorporated with the parenchyma of the nucleus; and such plants are said to be destitute of albumen. In others, however, numerous globules are deposited on the inside of the sac, and these by their agglomeration constitute the endosperm (fig. 130, c), inclosed in which is the embryo (fig. 130, d). But the almost complete destruction of the parenchyma of the nucleus, and great development of the embryonic sac, does not always take place: for in some plants the sac is only enlarged sufficiently to contain the embryo, and the parenchyma is to be observed (fig. 130, e) in the ripe seed filled with globules of a starchy substance, and is thus converted into a body similar to the endosperm; but, from its different situation and mode of formation, is called by another name in order to distinguish it, viz. the perisperm. In a few plants both the endosperm and perisperm may be traced, as in the water- We adopt these terms in conformity with Brongniart; but we must observe that systematic writers use these words, as well as albumen, promiscuously. In common language these are applied to that body which is to be sometimes found between the embryo and the coats of the seed, and whose cellular substance is totally different from the organized embryo; but when botanists discovered, as in the water-lily, in the Scitamineae, Piperaceae, and some other tribes (fig. 132), not only the albumen, but a second body more immediately surrounding the embryo, they gave this name of vitellus (Brown), or sac to the embryo (Lindley). Brown, however, afterwards showed that the vitellus was a kind of albumen, and that two kinds might exist in the same plant; and more lately Brongniart has suggested the propriety of employing expressions for each. Perhaps, on the whole, the term albumen, so generally adopted, might be used promiscuously for whichever is developed, and when it is necessary to distinguish both, to employ the terms endosperm and perisperm. We object to the use of the phrases vitellus, and sac to the embryo, because in many instances the albumen is entirely formed of this supposed sac or vitellus, and that if these words are to be adopted, they ought to be so constantly, and not in those cases only where both parts of the albumen are visible.

The nature of the albumen is of great importance: it is farinaceous in the grasses; coriaceous and almost cartilaginous in many umbelliferæ; ruminated when it is wrinkled by reason of prolongations of the coat of the seed into the folds of the albumen, as in the Annonaceæ; fleshy in most of the Euphorbiaceæ; horny, as in the coffee-bean; or thin and membranous, as in many Labiatae.

The embryo, as we have already said, is that organized body existing in the perfect seed after fecundation, which is destined to become a plant similar in all respects to the parent. It may either have or be without an albumen. When the albumen is present, and the embryo is applied to a point on its surface, it is said to be external (exterior); or if rolled round it, is peripheric. If shut up within the albumen, it is said to be inclosed (inclusus), and then may be either in the centre of the albumen (centrælis), or not in the centre (eccentricus). Usually there is but one embryo in each seed; but plants occur in which there are more than one, as the Allium fragrans, mistletoe (fig. 133), &c.

As the embryo is already organized in the seed, and becomes a plant by mere development, so all the parts of the future plant must exist in it, although in a mere rudimentary state. It must, therefore, contain the rudiments of the root, of the stem, and of the leaves.

Radicle. This is the rudiment of the root (fig. 134, a), and by germination becomes a root. Such may either happen by the mere elongation of the exposed radicle, or by its bursting through a peculiar envelope, and protruding the root from within. Plants which have this cover to the radicle are termed endorhizæ (fig. 135, a), and those which have none exorhizæ. Moreover, with very few exceptions, Glossoglossæ, and which are generally attended with other peculiarities, all exogenous plants are Exorhizæ, and the endogenous, Endorhizæ; so that the radicle indicates the future structure of the stem. The radicle is usually quite distinct from the albumen; but in Cycadæ and Coniferae there is an organic connection between them. Hence Richard has raised these orders to a distinct class, and called them synorhizæ.

The neck or collum is the line of separation between the radicle and the portion above it.

The Plumule (fig. 134, c), is what is destined to become the stem, and is therefore a rudimentary leaf-bud. It is by some divided into the cauliculus, or the portion between the radicle and the cotyledons, and the gemmule, or that which is situated above the cotyledons. If, however, our idea of the plumule be correct, the cauliculus corresponds to the neck or collum, while the gemmule is all that constitutes the true plumule. The plumule is often undistinguishable from the cotyledons, as in most of the exogenous plants that have albumen; while it is pretty evident in all endogeneæ without albumen. Among the endogeneæ the plumule is frequently rolled up in the cotyledon, and is not observable till after germination.

The cotyledons (fig. 134, b) are the primordial leaves of the plant; and as the plumule corresponds to a leaf-bud, so the cotyledons must be lateral, and situated at its base. We have already observed that in exogeneæ the leaves towards the bottom of the plant have a tendency to be opposite, and in endogeneæ alternate. In the embryo, then, where there can be but few leaves, we may naturally expect this disposition to be exact; and in fact it is so, exogeneæ having opposite or verticillate cotyledons, and endogeneæ alternate. In the former case they are usually two in number, whence exogenous plants are also called dicotyledonous; but sometimes there are more than two, as in the pine. These, however, being in a whorl, are mere modifications of the opposite cotyledons; and it has not been thought necessary to distinguish them from the dicotyledonous. When the cotyledons alternate, it is obvious that one only can be present at the base of the plumule; hence endogenous plants are called monocotyledonous. In some of these the first leaf of the plumule is at the same time slightly developed, whence botanists have supposed that some endogeneæ have two cotyledons. Their alternating with each other will, however, completely distinguish them from the dicotyledonous plants. Sometimes the two cotyledons of the exogeneæ are consolidated into one piece, as in Lecythus; in other plants, in which the leaves are reduced to mere scales, the cotyledons are also in a reduced state, and scarcely perceptible; but we have no right to infer, as some have done, that the embryo has none at all, or is acotyledonous. The cotyledons are erect, and placed close to each other, containing between them the plumule; they may be fleshy or foliaceous, narrow and semicylindrical, or broad and

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1 We have already stated Mirbel's view of the structure of the ovulum, and said that he has pointed out five distinct periods of development. In the first, the ovulum is scarcely perceptible, being a small palpy conical substance, without a foramen. In the second, the exostome and endostome open, and they are to be perceived dilating insensibly until they have attained their maximum. The primine and secundine are manifest, as is also the tercine; but this only puts on the appearance of a round or conical cellular mass, of which the apex protrudes beyond the secundine. In the third period the primine and secundine, united together, increase much in size, have their double orifice closed, and consequently conceal the tercine, which becomes a membranous ring. In the fourth period the quintine arises from the internal surface of the nucleus, and the quintine is elevated into a narrow utricle attached by the one extremity to the point corresponding to the tercine, and by the other to that corresponding to the endostome. This is the period in which the ovule passes into the state of a seed. In the fifth period the quintine expands, the embryo exhibits the cotyledons as well as the tercine, and the quintine is full of fluid; and the existence of the albumen is formed either in the cells of the quintine, or in those of the quintine or tercine, when it is no longer possible to recognize the different envelopes of the ovule. These considerations of Mirbel, though apparently different, are in reality much the same as those of Brongniart, the quintine corresponding to the parenchyma of the embryo, and the quintine to the embryonic sac. Glossology, flat; they may be plane, or plicate, or conduplicate (fig. 136), as in the cabbage, or convolute (fig. 139) or wrinkled; they may be entire, or lobed, or divided. They are said to be hypogeous when they remain under ground during germination; or epigeous, when, by an elongation of the column, they rise out of the ground during that process, as in the bean.

Having thus explained these parts, we have to notice the direction of the embryo. It may be straight or curved. The radicle is the base of the embryo, and the summit of the cotyledon the apex. Now, as the hilum is the base of the seed, so, when the radicle points towards the hilum, the embryo has the same direction as the seed, and is said to be homotropous, and if at the same time it be straight, orthotropous; and when the cotyledons point to the hilum, it is inverted, or is called antitropous. When it assumes a horizontal direction, or lies across the seed, and has not the same direction with it, it is heterotropous. And, lastly, in a curved seed, both extremities of the embryo may be turned towards the hilum, and it has been then termed amphitropous (fig. 140); but this is a modification of the antitropous. It has been now discovered that the radicle, or base of the embryo, is always situated at the foramen of the ovule or micropyle of the seed, and that the other or cotyledonal extremity is invariably directed towards the chalaza. If, then, the nucleus of the ovule have a contrary direction to the ovule itself, or if the micropyle be near the hilum, the embryo is homotropous; but if the nucleus be erect, or the micropyle be at the apex of the seed, it is orthotropous; and if the micropyle be at the side of the seed, it is heterotropous. In a curved seed, where the micropyle and chalaza are brought nearly into contact, we have the amphitropous embryo.

The position of the hilum in regard to the radicle, or, as one may say, the direction of the embryo with respect to the seed, is called the spermatic direction of the embryo, and is usually of great importance in defining most natural groups. Thus, in the horse-chestnut, where there are two seeds in each cell, of which the one is erect and the other inverted, or rather resupinate, the spermatic direction of the embryo is the same in each. But in some tribes, as the Proteaceae, the situation of the hilum on the seed appears to be variable; in which case we must resort to the pericarpic direction of the embryo, or its direction relatively to the fruit; and then, when it has the same direction as the fruit, it is erect, or the radicle is said to be inferior; and when it has an opposite direction, it is inserted, or the radicle is superior.

In a curved embryo, the relative position of the radicle and cotyledons is of great importance. Upon this De Candolle has founded his divisions of the cruciferous. When the radicle is so bent that it touches the back of one of the cotyledons, it is said to be dorsal, or the cotyledons incumbent (fig. 137). When it is applied to the edge or cleft of the cotyledons it is lateral, or the cotyledons are aduncuous (fig. 138). The same terms are analogically applied, even when the radicle is very slightly bent, but where, by a continuation of the bend, it might touch the back or edge of the cotyledons, as in the genus Polygonum.

Arrangement of the Organs of Reproduction.

All the organs of reproduction being modified leaves,

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1 Mirbel takes notice of an anomaly in the Primulaceae and Plantaginaceae, arising from the unequal development of the parts of the ovule. Here the primule sac or testa, in consequence of an extraordinary increase on the extensible side of the ovule, and a gradual contraction of the opposite one, has by degrees the exostome turned towards the chalaza, so that at last, as in other curved seeds, the two extremities coalesce; but the extensible side of the secundine, and even of the tercine or nucleus, soon ceases to increase with the corresponding side of the primule; so that the embryo, of which the radicle remained close to the summit of the internal envelopes, becomes stationary with the endostome, whilst the exostome has pursued its course and does not stop till it reaches the base of the ovule. The examination, then, of a simple solitary pistillum will thus, although we may have before us no more than a flower without the bracteae, determine the anterior and posterior situation of the lobes of the calyx or sepals. In the same way, when the division of the flower is quinary, and the carpels are reduced to two, the one is usually anterior, and the other posterior; or the solitary carpel being anterior, the addition to it is posterior. The only exception to this with which Mr Brown (who first laid any stress upon it) appears to be acquainted, was in some genera of Dilleniaceae. Martius, and following him Lindley, have distinguished Gentianaceae from their allies by the two carpels being placed right and left, and not anterior and posterior; but perhaps these able naturalists have not taken into due consideration the nature of the inflorescence and the consequent position of the bracteae. At present, therefore, we do not consider that tribe as an exception. In Dilleniaceae even, if we understand rightly the structure of the order, the apparent exceptions are caused by peculiarities upon which it were improper here to enter, may even imprudent, for no one in Europe has had the same opportunities of studying the group as the distinguished naturalist to whom we have alluded.

With regard to the number of parts in each whorl of the flowers, the symmetrical number is five among the dicotyledonous, or sometimes four, while in the monocotyledonous it is three. When, however, we consider that, on the one hand, there may be a reduction of parts, by the sepals, petals, stamens, and carpels, being much subject to abortion and union, and, on the other, an excess, either by multiplication, by more series than one of the same kind being developed; or by the combination of several flowers into one, we may easily conceive how few plants belong either to pentandria pentagynia, or to pentandria monogynia with a five-celled fruit.

Some botanists have supposed that the calyx and corolla form only one envelope; but this question seemed put to rest till the complete number of stamens and styles were found each equal to the conjunct number of both the floral coverings, when we have seen it revived. But we would suggest to those who may be inclined to adopt such an opinion, the difficulty of the case when petals are placed before the sepals. If these formed one envelope, then we must suppose the alternating petals abortive, and the apparent one a transformed stamen; and this supposition might be true if we never found a real stamen also opposite to the sepal and petal; but the Berberidaceae form at once an exception. We are aware that such a difficulty might be partly overcome by viewing the calyx of the Berberidaceae as a series of bracteae; so that we should have but one floral covering, and thus approach them to the Laurineae; for, by the abortion of some stamens, there is nothing to prevent the others being opposite to the petal, provided the petals were not also opposite to the sepals.

Having now at length explained the reproductive organs of vascular plants, we cannot pass over the cellular. In all these, as we have already said, there are no spiral vessels; and if, as we imagine, such are essential to the formation of a fecundating pollen, and of an embryo, we shall have no difficulty of denying to the whole class a real seed. Some botanists have insisted on the presence of male and female flowers; but if these do exist, they are in so very modified a state, so small, and so obscure, that all cellular plants have been invariably termed cryptogamous or agamos, in opposition to vascular plants, or those with spiral vessels in which there are flowers, and hence called phanerogamous or phanerogamous, from their sexes being evident and well formed. From the imperfection of the pollen and ovula (allowing such to exist) no embryo is formed, and thus cellulares are by some called arhizae (without a radicle), and by others acotyledonous (without cotyledons); both of these terms, however, from their allusion to an embryo, are, in our opinion, subject to criticism, so that those at one time adopted by Richard, of embryonate (with sexes, seeds, and embryo), and embryonate (without sexes, without seeds, and without an embryo), for the two grand divisions of vegetables, are more strictly correct. But if cellular plants have no seeds, how are they reproduced? Linnaeus has laid down the rule ovum vivum ex oro; but at that time the anatomical structure and physiology of the ovum was not so well understood; and there does not seem to be any doubt in the present day, that where spiral vessels are not present, a new individual may be formed by mere dilatation of some portion of the parent plant suited to the purpose, remotely similar to the multiplication of polypi in the animal kingdom, or even to spurious leaf-buds among vegetables. The portions thus capable of expansion have been by some termed seeds, from a general resemblance to true seeds, but are strictly called sporules. These sporules appear to give rise to a plant, in many cases, by elongating at some one point that seems to be only determined by contingent circumstances. In the ductulous cellular plants (we allude chiefly to those ferns with a rhizoma, for these alone have been examined with sufficient care) the sporule elongates into what at first has the appearance of a short club-shaped body (fig. 141) with two or three transverse darker coloured streaks. This, then, by degrees expands into a flat cellular and somewhat foli-

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1 Since the above was written, we have received a work by M. Dunal of Montpellier on the floral organs. This distinguished botanist considers that all the parts of a flower in its perfect state may be referred to three systems, which are respectively composed of several verticils or series in the following order, the divisions of each verticil constantly alternating with those of the preceding verticil. I. Cycloidal system, and always sterile. Of this there are three verticils, the first being sometimes called exterior sepals; the second is often termed by botanists an outer calyx; the third is the calyx of authors, and within its segments, and opposite to them, and often adhering with them, are an equal number of scales or lepida analogous to those in the next system, but which form only a part of this third verticil; and these scales cover the whole inside of the calyx in many achlamydeous. II. Male reproductive system, or androecium. This is composed of two ranks, an exterior and interior. Of the former, the first verticil furnishes the petals, in the axils of which are found scales or lepida, being the first of four verticils; the second verticil is of an equal number of petals, and alternates with them. The inner androecium has also two verticils. III. Female reproductive system, or gynoecium, consisting likewise of two verticils, the first of which usually constitutes the fruit, and consequently has its divisions opposed to those of the calyx or third verticil of the cycloidal system. Thus, the whole parts of the flower consist of nine series or verticils. The lepida or stamens found in the axils of the petals or first verticil of the exterior androecium, as well as the real stamens, are often separated into several, or, as Dunal terms them, chorizate, as in the almond. The fleshy disoid torus found in some plants he supposes to arise from the abortion of the inner androecium; a perigynous ring or disc, as in the Santalaceae, he supposes to be formed by the union of the lepida and filaments of the outer androecium. We shall not here enter into a discussion on the merits of this theory, which it is difficult to understand without a reference to M. Dunal's figures; but shall merely observe that it is exceedingly ingenious, and, if properly substantiated, may explain several anomalies in the structure of flowers hitherto involved in considerable obscurity. Glossology, ceous substance (fig. 142), setting out radicular fibres from its margin; and these being now capable of deriving immediate nourishment from the earth, the body of the sporule disappears. This flat substance appears by elongation to become the rhizoma; for soon after it is fixed to the ground, it emits, from a point on its upper surface (fig. 143), a thread, which is afterwards the stipes and the leafy part of the plant. Mosses germinate nearly in the same way; the clavate, and as if articulated, body arises from the sporule, and then elongates, branches, and forms the radicular portion, from some part of which the stem (as it is called) is projected, bearing the leaves (See Phascum serratum, fig. 144). Many Hepaticae germinate as the mosses. Conifers (part of the Algae) arise like the roots of mosses, and these fibres afterwards more or less unite together. Most lichens germinate like the ferns, the dilated filament becoming the frond. The Fungi have not been well observed in this respect; but it seems probable that, in the greater number, the whole mass is formed by the mere expansion of the sporule. How in all these orders the sporules are formed from the cells of the parent plant, and how they are endowed with the power of expansion, is a difficulty not easily solved; but this, as well as the investigation of the vivifying principle of the pollen on the embryo in vascular vegetables, is a subject purely physiological, and does not fall within our limits. We shall, however, merely state the only analogy, and it is a distant one, we can trace between these. Sporules are brought into life by coming into contact with external moisture, while the granules of pollen may be viewed as sporules that require to be fully shaped and fostered by the juices in the interior of the embryonic sac.

1. Equisetaceae.—The stems, and often the principal branches, of this tribe, are terminated by an ovate or conical spike, or rather raceme (fig. 145), composed of several verticillated scales (fig. 146), which are pedicellate, peltate, and angular. From the under side of these scales several wedge-shaped involucra or indusia project downwards, and burst longitudinally on the side next the pedicel, and discharge a multitude of globules. These globules (fig. 147), when seen under the microscope, consist of a central green compact spherical body, furnished at its base with four elongated clavate filaments, slightly united by pairs of an elastic nature, so that when moist they twist spirally round the central portion, but when dry unroll and expand themselves, bearing on them many minute granules. The use of these parts is unknown. Hedwig supposed the central body to be a pistillum, and that each pair of elastic filaments formed one stamen, whose pollen was the granules. Brongniart, tracing in these plants a general resemblance to Coniferae and Cycadées, presumes that the central body is a naked ovulum, and the filaments four grains of pollen united in pairs to its base. But although we admit either of these theories, we cannot regard the male organs as perfect; and the uniform structure of the supposed pistil or ovule militates against both hypotheses. Perhaps the central body may be viewed as a short seta or receptacle, analogous to that found in Ferns; the clavate filaments would then supply the place of a theca and annulus, while the minute granules would be sporules. This view is probable, if we consider each globule with the filaments as the result of a transformed frond.

2. Filices.—The organs of reproduction, commonly called the fructification, of ferns, arise from veins either on the under surface of the frond, or at its margin. In some genera the frond, or a part of it, becomes deformed, and seems entirely covered by these organs. Each cluster of organs is called a sorus (fig. 148 and 149), and is sometimes protected by a membrane termed an involucre or indusium (as in fig. 148), which is always attached to the Glossolea veins. This indusium is said to be plane when it lies flat upon the sorus; or peltate when more or less circular, but PL CXY depressed in its centre so as to form a kind of small pillar in the middle of the sorus; or reniform when it is the half of a peltate involucre, and thus resembling a half circle, attached by its centre on the one side of the sorus. It is squamiform or scale-like when it has the appearance of the scales of the frond. It may be continuous when the involucra of several sori are united into one uninterrupted line, and is single or double according as it extends from the vein on one or on both sides of the sorus. Thus a peltate involucre is double, and consists of two reniform ones. An involucremum is usually superior, but is sometimes inferior, or placed under the sorus, and surrounds it. It may either open outward (exterius delhisceus) in an opposite direction to the midrib, or inwards (interius delhisceus) towards the midrib; and when it is inferior, may burst from the apex into laciniæ or into two valves, or the upper part may disappear, leaving the lower cup-shaped (involucremum pateriforme). Sometimes the part of the vein to which the reproductive organs are attached is projected from the frond into the sorus, and is then called a receptacle. The sori may be fixed to the middle of a vein, or at its bifurcation, or at its extremity. They are round, or linear, or reniform, distinct or confluent, or continuous. They consist of groups of capsules; these, called more properly thecae (fig. 149), are either pedicellate, with the stalk passing round them in the form of an elastic ring or annulus, or are sessile, and usually destitute of such a ring; the former are called annulate, the latter exannulate. These thecae either burst open irregularly, or into two valves, or on the opposite side from the ring (fig. 150) when it is present. The sporules seem arranged without order in the interior. The sori may be considered as a group of fronds, the stalk of the theca as a modified stipes, the annulus as the midrib or rachis, and the theca itself as the transformed frondose portion. This highly probable view was first, we believe, suggested by Mr Lindley. Hedwig and others, who have wished to discover sexual organs among ferns, have been much puzzled, each having a different opinion, though none seems as yet worthy of notice.

3. Marsiliaceae.—The fructification is situated at, or Marsilia very near the root or rhizoma; in one plant along the secund petiole of the frond or leaf. It consists of a somewhat globular involucremum (fig. 151 and 152), of a leathery or membranous texture. This, unlike the ferns, does not open, and is probably composed of a transformed frond, the veins of which give rise to one or more partitions; hence the involucremum appears to have sometimes several cells. Attached to the veins or partitions are small bodies, apparently of two different kinds. Of these, in Marsilia (fig. 152), the one (fig. 153, a) is an oval-stalked theca, containing corpuscles, some large and roundish, others minute and angular. The other kind are very small bags filled with minute granules, and attached (fig. 153, b), several together, to the stalk of the theca. The theca, by the sexualists, has been considered a pistillum, and the bags as anthers. In Pilularia the structure is much the same, only the supposed anthers occupy the upper portion of the involucremum, and the theca the lower. In Salvinia the anthers consist of grains, attached by long threads to a central column; in Azolla they are angular, and inserted upon a central body that occupies the upper half of the involucre, while the lower half is filled with a turbid fluid, and the thecae are placed within a different involucremum.

4. Lycopodiaceae. Here the organs of reproduction are Lycopodiaceous or in spikes, and are composed of roundish cap-diacces.