Legume - Development of seeds

Outer epidermis of the ovary usually forms the exocarp of the leguminous pod. Next few cell layers constitute the mesocarp with thick-walled parenchyma. The endocarp consists of sclerenchyma on the inside of which is epidermis or a few layers of parenchyma and epidermis. In Astragalus macrocarpus, for example, inside the sclerenchymatous part of endocarp there is a thin-walled hypodermis and an epidermis. Vascular bundles are located in the mesocarp accompanied by some sclerenchymatous cells. The two valves of the dried legume usually twist, resulting in their opening and scattering of seeds. The twisting and opening of valves is brought about by shrinkage of the sclerenchymatous cell layers which are obliquely oriented.