Seed

A seed is the reproductive unit that develops from a fertilised, mature ovule. It is made up of a seed coat and an embryo, with or without endosperm. The embryo contains a radicle, a plumule, and one or two cotyledons. The outermost covering of the seed is the seed coat, which shows an outer layer called the testa and an inner layer called the tegmen. The hilum is a scar on the seed coat marking the point through which the seed was attached to the fruit. The embryo lies enclosed within the seed coat, and its embryonal axis consists of the radicle and the plumule; the part of the embryonal axis between the cotyledon(s) and the plumule is the epicotyl, while the part between the cotyledon(s) and the radicle is the hypocotyl. The endosperm formed in the seed is nutritive tissue, and the food stored in it may be only partially used up duri …