(Greek, kotyle = a deep cup) In the embryos of seed plants, the "seed leaves," in which nutrients are stored for use after germination. Used also to describe the structure of the placenta. (More? Placenta Notes) cr - cy
the embryo leaf or leaves of seed plants that absorbs nutrients packaged in the seed, until the seedling is able to produce its first true leaves and begin photosynthesis. "The number of cotyledons present in an embryo is an important character in the classification of flowering plants (angiosperms). Monocotyledons (such as grasses, palms, and lilies) have a single cotyledon, whereas dicotyledons (the majority of plant species) have two. In seeds that also contain endosperm (nutritive tissue), the cotyledons are thin, but where they are the primary food-storing tissue, as in peas and beans, they may be quite large. After germination the cotyledons either remain below ground (hypogeal) or, more commonly, spread out above soil level (epigeal) and become the first green leaves. In gymnosperms there may be up to a dozen cotyledons within each seed." Tiscali. Image from the Online Biology Book by Dr. Mike Farabee of Estrella Mountain Community College.
part of seed surrounding the embryo, the cotyledon serves as a source of nutrients for the germinating plant. The number of cotyledons in the seed serves as a basis for classifying angiosperms into monocotyledons, with one cotyledon, and dicotyledons, with two.
the embryo leaf or leaves of seed plants that usually stores or absorbs food in a young seedling; in angiosperms (flowering plants) the following distinction is made with respect to the cotyledons: di cots have two cotyledons and mono cots have one cotyledon
n. The "seed leaves" produced by the embryo of a seed plant that serve to absorb nutrients packaged in the seed, until the seedling is able to produce its first true leaves and begin photosynthesis; the number of cotyledons is a key feature for the identification of the two major groups of flowering plants.
Portions of the stratum compactum persist and are condensed to form a series of septa, which extend from the basal plate through the thickness of the placenta and subdivide it into the lobules or cotyledons seen on the uterine surface of the detached placenta.