a genus of plants belonging to the pentandria clas. See BOTANY Index.

SEMIN, SEED. See Botany Index.

With respect to number, plants are either furnished with one seed, as sea-pink and bistort; two, as wood-roof and the umbelliferous plants; three, as spurge; four, as the lip-flowers of Tournefort and rough-leafed 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, fleck 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 sebeften, 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, ammamnia, rampions, and throat-wort.

With respect to situation, they are either dispersed promiscuously through the pulp (Jemina nidulantia), 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 (Jemina 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 (Jemina testa) are contained in some vessel, whether of the capsule, pod, berry, apple, or cherry kind.

A simple seed is such as bears neither crown, wing, nor downy pappus; the varieties in seeds, arising from these circumstances, are particularly enumerated under their respective heads.

In assimilating the animal and vegetable kingdoms, Linnaeus denominates seeds 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 seeds; of elecampane, 3000; of fun-flower, 4000; of poppy, 32,000; of a spike of cat's tail, 10,000 and upwards: a single fruit, or seed-vessel, of tobacco, contains 1000 seeds; that of white poppy, 8000. Mr Ray relates, from experiments made by himself, that 1012 tobacco seeds are equal in weight to one grain; and that the weight of the whole quantum of seeds in a single tobacco plant, is such as must, according to the above proportion, determine their number to be 360,000. The same author estimates the annual produce of a single stalk of spleenwort to be upwards of one million of seeds.

The dissemination of plants respects the different methods or vehicles by which nature has contrived to diffuse 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 seeds themselves.

1. The seeds 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-vite, meadow rue, and jessamine, and some umbelliferous plants; furnished with a pappus, or downy crown, as in valerian, poplar, reed, succulent-fallowwort, cotton-tree, and many of the compound flowers; placed within a winged calyx or seed-vessel, as in fabious, sea-pink, dock, dioscorea, ash, maple, and elm-trees, logwood and wood; or, lastly, contained within a swelled calyx or seed vessel, as in winter cherry, cucubalus, melilot, bladder-nut, fumatory, bladder-sena, heart-feed, and chick-pea.

3. Many birds swallow the seeds of vancelloe, juniper, milletoe, oats, millet, and other grasses, and void them entire. Squirrels, rats, parrots, and other animals, suffer many of the seeds 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 seeds which have been scattered upon its surface. Again, some seeds attach themselves to animals, by means of crotchets, hooks, or hairs, which are either affixed to the seeds themselves, as in hound's tongue, mouse-ear, vervain, carrot, bastard parsley, fanicle, water hemp-agrimony, arctopus, and verbenas; to their calyx, as in burdock, agrimony, rhexia, small wild bugloss, dock, nettle, pellitory, and feedwort; or to their fruit or seed-vessel, as in liquorice, enchanter's nightshade, croswort, cleavers, French honey-fuckle, and arrow-headed grafs.

4. The seeds 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 papus, as in centaurea crupina; or in their capsule, as in geranium, herb-bennet, African spirea, fraxinella, horse-tail, ballam, Malabar nut, cucumber, elaterium, and male ballam apple.

SEmen, in the animal economy. See Physiology and Anatomy Index.

SEmen Sanctum, or Santonicum. See Artemisia.