Cotyledon

A cotyledon is the first leaf or one of the first pair of leaves or whorl of leaves on a newly developed plant emerging from the seed embryo[?]. The number of cotyledons a plant has is one common way that biologists group plant species. Plants with one cotyledon are therefore "monocotyledons" (or simply monocots) and plants with two are "dicotyledons" (or simply dicots).