With the help of a suitable labelled diagram, describe the structure of a dicot seed.
It is a dicotyledonous and non-endospermic seed. It is produced in a long cylindrical pod (fruit – phali) External characters. The seed is brown or whitish brown in colour. The seed is hard and smooth and kidney-shaped i.e. Convex on one side and concave on the other side. The concave side bears whitish scar called hilum. It is the place which is attached to the wall of the pod through a stalk called funicle. At one side of the hilum is a small pore called micropyle water enters through it.
Internal structure — The seed is covered by a hard, tough covering called testa. Inner to the tests is the embryo. The embryo consists of two cotyledons and embryo axis. The Embryo axis has plumule and radicle. The plumule is present in between the two cotyledons and its top bears two folded tiny leaves. It forms future shoot and leaves of the growing seed. Radicle is rod-shaped and is out of the two cotyledons. It forms the root of the growing seed. When the seed grows the two cotyledons come out of the soil and form cotyledonary leaves and turn green in colour. Cotyledons give food to the growing seedling as it has food. The germination in this seed is epigeal as cotyledons come outside the soil in the growing seed.
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- Classification and Structure of Seeds - Dicot Seed Structure (Bean Seed)