Seed Structure The outer covering of a seed is called the seed coat. Seed coats help protect the embryo from injury and also from drying out. Seed coats can be thin and soft as in beans or thick and hard as in locust or coconut seeds. Endosperm, a temporary food supply, is packed around the embryo in the form of special leaves called cotyledons or seed leaves. These generally are the first parts visible when the seed germinates. Plants are classified based upon the number of seed leaves (cotyledons) in the seed. Plants such as grasses can be monocots, containing one cotyledon. Dicots are plants that have two cotyledons.