Reproductive structure of higher plants (angiosperms
). It develops from a fertilized ovule and consists of an embryo and a food store, surrounded and protected by an outer seed coat, called the testa. The food store is contained either in a specialized nutritive tissue, the endosperm
, or in the cotyledons
of the embryo itself. In angiosperms the seed is enclosed within a fruit
, whereas in gymnosperms it is usually naked and unprotected, once shed from the female cone.
the seed develops into a new plant.
Seeds may be dispersed from the parent plant in a number of different ways. Agents of dispersal include animals, as with burs
and fleshy edible fruits, and wind, where the seed or fruit may be winged or plumed. Water can disperse seeds or fruits that float, and various mechanical devices may eject seeds from the fruit, as in the pods of some leguminous plants (see legume
There may be a delay in the germination of some seeds to ensure that growth occurs under favourable conditions (see dormancy
). Most seeds remain viable for at least 15 years if dried to about 5% water and kept at -20°C/-4°F, although 20% of them will not survive this process.
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