Bean cotyledons is a significant part of the embryo within the seed of a plant. Upon germination, the cotyledon may become the embryonic first leaves of a seedling. The number of cotyledons present is one characteristic used by botanists to classify the flowering plants (angiosperms). Species with one cotyledon are called monocotyledonous ('monocots'). Plants with two embryonic leaves are termed dicotyledonous ('dicots') and placed in the class Magnoliopsida.