cotylédons

Cotyledons are embryonic leaves in seed-bearing plants, one or more of which are the first leaves to appear from a germinating seed. The word "cotyledon" comes from the Greek words kotylēdōn, meaning "a small cup," and literally "hollow of a ring." In dicotyledonous plants, there are two cotyledons, and in monocotyledonous plants, there is only one. In some plants, the cotyledons emerge above ground and become green, functioning as the first leaves. In other plants, they remain below ground and serve as a food reserve for the developing embryo.

The number of cotyledons is a key characteristic used to classify flowering plants. Plants with one cotyledon are called monocots, while those with two are called dicots. Examples of monocots include grasses, lilies, and orchids. Examples of dicots include beans, roses, and oaks. The structure and function of cotyledons can vary significantly among different plant species. For example, in some plants, the cotyledons store food reserves, while in others, they are photosynthetic. The fate of the cotyledons after germination also differs. Some wither and fall off soon after the true leaves emerge, while others persist and contribute to the plant's overall structure for a longer period. Their presence and behavior are fundamental to understanding early plant development.