The first leaf, or one of the first pair or whorl of leaves, developed by the embryo of a seed plant.
Seed-leaf, the first-formed leaf that is often of a different shape from later leaves.
One of the pair of first leaves of a seed ling in Dicotyledons, which is one of the two great sub-divisions of the flowering plants. Dicotyledon leaves are usually net-veined. The single first leaf of a seedling in Monocotyledons, which is the other of the two great sub-divisions of the flowering plants. Monocotyledon leaves are usually parallel-veined.
One of the divisions of a placenta.
The leaves of the embryo—as the oily meats of the butternut, which consist of the cotyledons only, joined by their connective.
Any of the major convex subdivisions of the mature placenta. Each cotyledon contains a major branch of the umbilical blood vessels, which branch further into the numerous villi that make up the surface of the cotyledon.