endocarps

Endocarp is the innermost layer of the pericarp, the fruit wall that surrounds the seed in flowering plants. It develops from the inner ovary wall and lies inside the mesocarp and exocarp. The endocarp’s primary role is to protect the seed as the fruit matures, and in some fruit types it also participates in seed dispersal.

In stone fruits, or drupes, the endocarp becomes a hard, lignified shell that surrounds the seed. Peaches, plums, cherries, and apricots are typical examples, where the stone is the endocarp.

Other fruits have a softer endocarp. In citrus fruits, the endocarp forms the thin, papery membranes that separate the juice sacs within each segment rather than a hard shell. Nuts such as walnuts, almonds, and coconuts feature a highly developed endocarp that becomes the protective shell around the seed or kernel; in coconuts, the endocarp is the hard, brown shell inside the fibrous husk.

In many berries and other fleshy fruits, the endocarp is thin or not readily distinguishable, as the pericarp remains mostly fleshy.

The endocarp is a useful feature in plant systematics and fruit anatomy, helping to classify fruit types and understand strategies for protecting seeds and promoting dispersal.