Seed:-

• Seed is the final product of sexual reproduction. It is the fertilized ovule formed inside fruits.
• It consists of seed coat(s), cotyledon(s), & an embryo axis.
• The cotyledons are simple, generally thick, and swollen due to the storage of food (as in legumes).
• Mature seeds may be non-albuminous or albuminous.
• 1. Non-albuminous seeds: have no residual endosperm as it is completely consumed during embryo development (e.g., pea, groundnut, beans).
• 2. Albuminous seeds: retain a part of the endosperm as it is not completely used up during embryo development (e.g., wheat, maize, barley, castor, coconut, sunflower).
• Occasionally, in some seeds (black pepper, beet etc) remnants of nucellus are also persistent. It is called perisperm.
• Integuments of ovules harden as tough protective seed coats. It has a small pore (micropyle) through which O₂ & water enter into the seed during germination.
• As the seed matures, its water content is reduced, and seeds become dry (10-15 % moisture by mass). The general metabolic activity of the embryo slows down.
• The embryo may enter a state of inactivity (dormancy). If favourable conditions are available (adequate moisture, oxygen and suitable temperature), they germinate.