cotyledon, seed leaf within the embryo of a seed. Cotyledons help supply the nutrition a plant embryo needs to germinate and become established as a photosynthetic organism and may themselves be a source of nutritional reserves or may aid the embryo in metabolizing nutrition stored elsewhere in the seed.

Are cotyledons seeds?

Cotyledons are the first leaves produced by plants. Cotyledons are not considered true leaves and are sometimes referred to as "seed leaves," because they are actually part of the seed or embryo of the plant.

What cotyledon contains?

The cotyledons contain (or in the case of gymnosperms and monocotyledons, have access to) the stored food reserves of the seed. As these reserves are used up, the cotyledons may turn green and begin photosynthesis, or may wither as the first true leaves take over food production for the seedling.