kotiledonlarn

Kotiledonlarn are embryonic leaves that form inside the seeds of flowering plants (angiosperms). They accompany the developing embryo and play a crucial role during germination, acting as the first source of nutrients or the first photosynthetic organs, depending on the species and seed type. The term covers both single and paired cotyledons and their diverse forms across plant groups.

In angiosperms there are two broad categories based on the number of cotyledons: monocotyledons (one cotyledon) and dicotyledons (two cotyledons). In monocots, the single cotyledon is usually called a scutellum and is involved in transferring nutrients from the endosperm to the embryo during germination. The monocot embryo is protected by structures such as the coleoptile and coleorhiza, and the cotyledon often remains below ground in a hypogeal germination, or appears as a small, non-photosynthetic organ in some species. In dicots, two cotyledons are common, and germination can be epigeal (cotyledons emerge above ground and may become photosynthetic) or hypogeal (cotyledons stay below ground).

Nutritional and developmental roles vary: in many dicots, cotyledons store starch, oils, and proteins and may gradually become green and photosynthetic after the seedling establishes photosynthesis. In endospermic seeds (endosperm present), cotyledons absorb nutrients from the endosperm; in exalbuminous seeds, the cotyledons themselves store most reserves. As seedlings grow, cotyledons may wither and fall or persist briefly as leaves or storage organs, while true leaves develop.