Explain about seed.

In angiosperms, the seed is the final product of sexual reproduction.

It is often described as a fertilised ovule. Seeds are formed inside fruits. A seed typically consists of seed coat $(s)$, cotyledon $(s)$ and an embryo axis. The cotyledons  of the embryo are simple structures, generally thick and swollen due to storage of food reserves (as in legumes).

Mature seeds may be non albuminous or albuminous. Non-albuminous seeds have no residual endosperm as it is completely consumed during embryo development (e.g., pea, groundnut).

Albuminous seeds retain a part of endosperm as it is not completely used up during embryo development (e.g., wheat, maize, barley, castor, sunflower). Occasionally, in some seeds such as black pepper and beet, remnants of nucellus are also persistent. This residual, persistent nucellus is the perisperm.