in the anatomy of plants, a kind of large bud, generally produced under the ground, upon or near the root of certain herbaceous plants, hence denominated bulbous.

A bulb is defined by Linnæus to be a species of hybernaculum, produced upon the descending caudex or root; consisting of stipule, petioli, the rudiments of the former leaves, and scales or bark.

To elucidate this definition, it is proper to remark, that every bud contains, in miniature or embryo, a plant, in every respect similar to the parent upon which it is seated. Plants therefore are perpetuated in the buds, as well as in the seeds; and the species may be renewed with equal efficacy in either way.

The tender rudiments of the future vegetable, of which the bud is composed, are inclosed, and during the severities of winter defended from cold and other external injuries, by a hard bark or rind, which generally consists of a number of scales placed over each other like tiles, and fastened together by means of a tenacious, resinous, and frequently odoriferous, substance. Thus defended, the buds remain upon different parts of the mother plant till the ensuing spring; and are, therefore, with great propriety, denominated by Linnæus the hybernaculum or winter-quarters of the future vegetable.

With respect to their place, buds are situated either upon the stem and branches, or upon the roots: the former are styled gemmae, or buds properly so called; but as they subsist several years by their roots, may be furnished with the other species of hybernaculum called bulbs, which, according to the definition, are seated upon the descending caudex or root.

Again, trees which are perennial, with a woody and durable stem or trunk, have generally proper buds or gemmae, but no bulbs.

In bulbous plants, as the tulip, onion, or lily, what we generally call the root, is in fact a bulb or hybernaculum, which incloses and secures the embryo or future shoot.

At the lower part of this bulb may be observed a fleshy knob or tubercle, from whence proceed a number of fibres or threads. This knob, with the fibres attached to and hanging from it, is, properly speaking, the true root; the upper part being only the cradle or nursery of the future stem, which after the bulb has repaired a certain number of times, it perishes; but not till it has produced at its sides a number of smaller bulbs or suckers for perpetuating the species.

One part of Linnæus's definition still remains obscure. The bulb, says he, is composed of the remains or rudiments of the former leaves of the plant; rudimenta foliorum praeteritorum.

It is easy to comprehend that buds contain the rudiments of the future leaves; but how can bulbs be said to contain the radiments of leaves that, to all appearance, are already perished? To explain this, let it be observed, that, in the opinion of very eminent botanists, the root, in a very great number of perennial herbs, is annually renewed or repaired out of the trunk or stalk itself; in which sense only, roots are properly said to descend.

In the perennials alluded to, the basis of the stalk continually, and by insensible degrees, descends below the surface of the earth, and is thus changed into a true root; which root, by the continuance of the said motion of the stalk, also descends; and thus, according to the durableness of its substance, becomes a longer or shorter root; the elder or lower part rotting off in proportion as the upper is generated out of the stalk. Thus, in brownwort, the basis of the stalk, sinking down by degrees till it is hid under the ground, becomes the upper part of the root; and continuing still to sink, the next year becomes the lower part, and the following year rots away.

This is exactly what obtains in bulbous roots, as well as in the far greater number of other herbaceous perennials; as arum, valerian, tansy, samphire, primrose, wood sorrel, iris, and others.

The immediate visible cause of this descent is the string-roots which this kind of trunks frequently puts forth; which descending themselves directly into the ground, serve like so many ropes for pulling the trunk after them. Hence the tuberous roots of iris are sometimes observed to reascend a little upon the rotting or fading away of the string roots which hang at them.

In bulbous roots, where the stalk and former leaves of the plant are sunk below, and formed into what is called the bulb or wintering of the future vegetable, the radicles or small fibres that hang from the bulb are to be considered as the root; that is, the part which furnishes nourishment to the plant: the several rinds and shells, whereof chiefly the bulbs consist, successively perish, and shrink up into so many dry skins; betwixt which, and in their centre, are formed other leaves and shells, and thus the bulb is perpetuated.

What has been said of the descent of roots by the sinking of the stalk, is further confirmed by the appearance of certain roots; as of valerian, plantago major, and the devil's bit, in which the lower part appears bitten or chopped off. In these the lower part rotting off as the upper descends, the living remainder becomes stumped, or seems bitten.

All bulbous roots, says the learned Dr Grew in his anatomy of plants, may be considered as hermaphrodite roots, or root and trunk both together; for the radicles or strings only are absolute roots; the bulb actually containing those parts which springing up make the body or leaves of the plant; so that it may be regarded as a large bud under ground.

Bulbous roots are said to be solid, when composed of one uniform lump of matter: tunicated, when formed of multitudes of coats surrounding one another; squamosè, when composed of, or covered with, lesser flakes; duplicate, when there are only two to each plant: and aggregate, when there is a congeries of such roots to each plant.

**BULBOCASTANUM.** See **BUNIUM**, Botany Index.