Plant embryos in seeds have structures called cotyledons. A cotyledon is the central portion of a seed embryo to which the epicotyls- the immature shoot, and the radicle- the immature roots, are attached.
Plants are classified according to the number of cotyledons present in the embryo. If the embryo has one cotyledon (monocotyledon) it is a monocot plant, and if there are two cotyledons (dicotyledon), it is a dicot plant.
Based on the type and location of storage materials, seeds can be subdivided into endosperms and non endosperms.
Endospermic seeds are those that have an endosperm in the mature seed. It is fleshy, oily, surrounds the embryo, and functions as the sole food storage organ. Inside the seed coat, a thin and papery cotyledon is present. Monocot plants have endospermic seeds.
Non-endospermic seeds do not have an endosperm in the mature seed. The cotyledons are thick and fleshy, and function as the sole food storage organs. Dicot plants have non-endospermic seeds.