Describe the structure of maize grain.

Explanation

It is a monocotyledonous, endospermic single seeded dry fruit called caryopsis. The grain is conical and flattened. On one side the broader end bears a papilla representing remains of the style. The same side has a depression in which a ridge indicates the position of underlying embryo. Hilum and micropyle are.absent. Surface is nearly smooth. The covering of the grain is made of fused pericarp and testa. 2/3 of the grain interior has food storage tissue of endosperm. It is rich in starch. A protein rich aleurone layer lies on the outside of endosperm. Embryo lies on one side towards the upper pointed part. A single large cotyledon lies lateral and parallel to the embryo axis. It is called scutellum., which is attached to the middle part of embryo axis. Its outer layer, in contact with endosperm is called epithelial layer. The layer secretes GA for formation of amylase during germination. Embryo axis ends in plumule towards broader side and radicle towards pointed side. Radicle has a root cap. Plumule bears a few small leaves. Sheaths derived from scutellum cover the two ends of embryo axis, undifferentiated coleorhiza over the radicle root cap region and hollow folial coleoptile over the plumule. Area of embryo axis is between plumule and cotyledonary node is epicotyl while the area between cotyledonary node and radicle is called hypocotyl.