Monocotyledonous Seed: Maize (Corn), Wheat, Rice is some important monocotyledon seeds, contains one cotyledon as store food for germination of seed. Actually these all are caryopsis fruit not seed because in all these seed coat is fused with fruit wall. The com grain is a flat oblong structure which externally it shows a large yellowish upper are which marks the position of endosperm and on the lower side, there is a small whitish area which contains the embryo. The outer 2 / 3 part of grain is endospenn and 1 / 3 part of grain is made up of embryo. Hilum and micropyle absent because it is fruit not seed. In longitudinal section of maize seed following structures are observed
- Seed coat
- Endospem
- Embryo.
1. Seed coat:
It is found as a thin yellow layer around the seed which actually formed by fusion of pericarp and seed coat.
2. Endosperm:
It is endospemiic seed because in mature seed endospenn is present. It is upper flattened yellow or white part of which stores starch as food. Outer part of endospenn which is attached with seed coat is made up of protein only andcalled as Aleurone layer. Inner part of endosperm is starch rich..
3. Embryo:
A large lateral single cotyledon is present in it which is called as Scutellum. Surface of scutellum which is in contact with endosperm is called as Epithelial layer. Epithelium layer produces Gibberellins hormone for mobilizing food reserve of endospenn at the time of seed gemination.
Embryo consists of embryo axis. End of embryo axis towards broader end has plumule which has few rudimentary leaves. End of embryo axis towards pointed end has redicle which covered by root cap. Extension of scutellum which covers plumule is called as Coleoptile Extension of scutellum which covers redicle is called as Coleorhiza