A cotyledon is a very significant part of the embryo within the seed of a plant. When the seed germinates, or begins to grow, the cotyledon become the first leaves of the seedling. The number of cotyledons present in the seed of a plant is used as a means of classification. Monocots are seeds with just one cotyledon, whereas dicots have two cotyledons. The cotyledons are the first part of the plant to emerge from the soil during germination. The cotyledons are important for the new plant as they contain the stored food reserves from the seed to give the plant the initial energy to grow.