Cotyledon

cotyledon

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. Angiosperms (flowering plants) whose embryos have a single cotyledon are grouped as monocots, or monocotyledonous plants; most embryos with two cotyledons are grouped as eudicots, or eudicotyledonous plants. The number of cotyledons in the embryos of seeds of gymnosperms is highly variable, ranging from 8 to 20 or more.