The fertilized ovule is called seed and possesses an embryo, endosperm and a protective coat. Seeds may be endospermous (wheat, maize, barley and sunflower) or non endospermous.
(Bean, Mango, Orchids and cucurbits).
Cicer seed (example for Dicot seed)
The mature seeds are attached to the fruit wall by a stalk called funiculus. The funiculus disappears leaving a scar called hilum. Below the hilum a small pore called micropyle is present. It facilitates entry of oxygen and water into the seeds during germination.
Each seed has a thick outer covering called seed coat. The seed coat is developed from integuments of the ovule. The outer coat is called testa and is hard whereas the inner coat
is thin, membranous and is called tegmen.
In Pea plant the tegmen and testa are fused. Two cotyledons laterally attached to the embryonic axis and store the food materials in pea whereas in other seeds like castor the endosperm contains reserve food and the cotyledons are thin. The portion of embryonal axis projecting beyond the cotyledons is called radicle or embryonic root. The other end of the axis called embryonic shoot is the plumule. Embryonal axis above the
level of cotyledon is called epicotyl whereas the cylindrical region between the level of cotyledon is called hypocotyl.
Oryza seed (example for Monocot seed)
The seed of paddy is one seeded and is called Caryopsis. Each seed remains enclosed by a brownish husk which consists of glumes arranged in two rows. The seed coat is a brownish, membranous layer closely adhered to
the grain. Endosperm forms the bulk of the grain and is the storage tissue. It is separated from embryo by a definite layer called epithelium.
The embryo is small and consists of one shield- shaped cotyledon known as scutellum present towards lateral side of embryonal axis.
A short axis with plumule and radicle protected by the root cap is present. The plumule is surrounded by a protective sheath called coleoptile. The radicle including root cap
is also covered by a protective sheath called coleorhiza. The scutellum supplies the growing embryo with food material absorbed from the
endosperm with the help of the epithelium