SEMEN, SEED. See BOTANY, sect. iv. p. 435.
With respect to number, plants are either furnished with one seed, as sea-pink and bistort; two, as wood-rose and the umbelliferous plants; three, as spurge; four, as the lip-flowers of Tournefort and rough-leaved plants of Ray; or many, as ranunculus, anemone, and poppy.
The form of seeds is likewise extremely various, being either large or small, round, oval, heart-shaped, kidney-shaped, angular, prickly, rough, hairy, wrinkled, sleek or shining, black, white, or brown. Most seeds have only one cell or internal cavity; those of lesser burdock, valerian, lamb's lettuce, cornelian cherry, and fescus, have two.
With respect to substance, seeds are either soft, membranaceous, or of a hard bony substance; as in gromwell, tamarind, and all the nuciferous plants.
In point of magnitude, seeds are either very large, as in the cocoa-nut; or very small, as in campanula, amaranth, rampions, and throat-wort.
With respect to situation, they are either dispersed promiscuously through the pulp (semina nidulantis), as in water-lily; affixed to a future or joining of the valves of the seed-vessel, as in the cross-shaped and pea-bloom flowers; or placed upon a placenta or receptacle within the seed vessel, as in tobacco and thorn-apple.
Seeds are said to be naked (semina nuda) which are not contained in a cover or vessel: such are those of the lip and compound flowers, the umbelliferous and rough-leaved plants; covered seeds (semina tecta) are
Semen contained in some vessel, whether of the capsule, pod, berry, apple, or cherry kind.
A simple feed is such as bears neither crown, wing, nor downy pappus; the varieties in feeds, arising from these circumstances, are particularly enumerated under their respective heads.
In assimilating the animal and vegetable kingdoms, Linnaeus denominates feeds the eggs of plants. The fecundity of plants is frequently marvellous; from a single plant or stalk of Indian Turkey wheat, are produced, in one summer, 2000 feeds; of elecampane, 3000; of sun-flower, 4000; of poppy, 32,000; of a spike of cat's tail, 10,000 and upwards: a single fruit, or feed-vessel, of tobacco, contains 1000 feeds; that of white poppy, 8000. Mr Ray relates, from experiments made by himself, that 1012 tobacco-feeds are equal in weight to one grain; and that the weight of the whole quantum of feeds in a single tobacco-plant, is such as must, according to the above proportion, determine their number to be 362,000. The same author estimates the annual produce of a single stalk of spleen-wort to be upwards of one million of feeds.
The dissemination of plants respects the different methods or vehicles by which nature has contrived to disperse their seeds for the purpose of increase. These by naturalists are generally reckoned four.
1. Rivers and running waters. 2. The wind. 3. Animals. 4. An elastic spring, peculiar to the feeds themselves.
1. The feeds which are carried along by rivers and torrents are frequently conveyed many hundreds of leagues from their native soil, and cast upon a very different climate, to which, however, by degrees they render themselves familiar.
2. Those which are carried by the wind, are either winged, as in fir-tree, trumpet-flower, tulip-tree, birch, arbor-vitæ, meadow-rue, and Jessamine, and some umbelliferous plants; furnished with a pappus, or downy crown, as in valerian, poplar, reed, succulent swallow-wort, cotton-tree, and many of the compound flowers; placed within a winged calyx or feed-vessel, as in scabious, sea-pink, dock, dioscorea, ash, maple, and elm-trees, logwood and woad; or lastly, contained within a swelled calyx or feed-vessel, as in winter-cherry, cucubulus, melilot, bladder-nut, fumitory, bladder-senna, heart-feed, and chick-pease.
3. Many birds swallow the feeds of vanelloe, juniper, mistletoe, oats, millet, and other grasses, and void them entire. Squirrels, rats, parrots, and other animals, suffer many of the feeds which they devour to escape, and thus in effect disseminate them. Moles, ants, earthworms, and other insects, by ploughing up the earth, admit a free passage to those feeds which have been scattered upon its surface. Again, some feeds attach themselves to animals, by means of hooks, crotchets, or hairs, which are either affixed to the feeds themselves, as in hound's tongue, mouse-ear, vervain, carrot, bastard-parley, fanicle, water hemp-agrimony, arctopis and verbesina; to their calyx, as in burdock, agrimony, rhexia, small wild bugloss, dock, nettle, pellitory, and lead-wort; or to their fruit or feed-vessel, as in liquorice, enchanters' night shade, cross-wort, elvers, French honey-suckle, and arrow-headed grass.
4. The feeds which disperse themselves by an elastic force, have that force resident either in their calyx, as
in oats and the greater number of ferns; in their pappus, as in centaurea crupina; or in their capsule, as in geranium, herb-bennet, African spirea, fraxinella, horse-tail, balsam, Malabar nut, cucumber, elaterium, and male balsam apple.