cotyledon


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cotyledon

(kŏt'əlēd`ən), in botany, a leaf of the embryo of a seedseed,
fertilized and ripened ovule, consisting of the plant embryo, varying amounts of stored food material, and a protective outer seed coat. Seeds are frequently confused with the fruit enclosing them in flowering plants, especially in grains and nuts.
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. The embryos of flowering plants, or angiospermsangiosperm
, term denoting seed plants in which the ovules, or young seeds, are enclosed within the ovary (that part of the pistil specialized for seed production), in contrast to the gymnosperms, in which the seeds are not enclosed within an ovary.
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, usually have either one cotyledon (the monocots) or two (the dicots). Seeds of gymnosperms, such as pines, may have numerous cotyledons. In some seeds the cotyledons are flat and leaflike; in others, such as the bean, the cotyledons store the seed's food reserve for germination and are fleshy. In most plants the cotyledons emerge above the soil with the seedling as it grows. They differ in form from the true leaves.

Cotyledon

 

one of the first leaves of a plant. The cotyledons form in the seed on the not yet differentiated body of the developing embryo. They often differ sharply in shape, internal structure, and, sometimes, function from subsequent leaves that arise on the growing point of the shoot. Gymnospermous plants have two to 15 cotyledons, dicotyledonous plants two cotyledons, and most monocotyledonous plants one cotyledon. When there is aboveground sprouting of dicotyledon seeds (for example, beans), green cotyledons emerge at the soil surface and for some time perform the functions of green leaves. In peas, oak, walnut, and a number of other plants the cotyledons upon sprouting remain in the seed and die after consumption of nutrient reserves. During the sprouting of many monocotyledons, the sheath portion of the cotyledon emerges from the seed, but the apex remains for some time in the endosperm, functioning as an organ of absorption. The same function is performed by the scutellum that remains in the seed of cereal grains; many botanists consider the scutellum to be a cotyledon.

cotyledon

[‚käd·əl′ēd·ən]
(botany)
The first leaf of the embryo of seed plants.

cotyledon

1. Botany a simple embryonic leaf in seed-bearing plants, which, in some species, forms the first green leaf after germination
2. Anatomy a tuft of villi on the mammalian placenta
References in periodicals archive ?
Once water has penetrated the seed, the tissues of the endosperm consisting of stored foods (macromolecules of starch, protein or lipids) and cotyledons (embryonic leaves) start the metabolic process called digestion.
These treatments included timing (control, early, and late) of cotyledon removal.
Embryo The rudimentary plant within the seed, consisting mostly of a single cotyledon, a plumule, and a root apex.
The internal anatomies of a monocot (has one cotyledon and parallel leaf venation) and dicot stem (has two cotyledons and reticulate leaf venation) are shown in Figure 6-16.
Enhanced regeneration of multiple shoots and plantlets in young cotyledons of Neem, Azadirachta indica A.
1A), whereas the highest concentration of fetal CRH RNA was present in STBM obtained by perfusion of a placental cotyledon (Fig.
Cotyledon, the name of a separate genus with rosettes of succulent leaves, has been appended to lewisias.
At two subsequent stages, in late fall prior to overwintering and in early spring prior to flowering, I quantified individual size by measuring three traits: cotyledon diameter, length of the most basal leaf (mm), and number of leaves.
Callus formation and shoot regeneration resulted in all hormone concentrations used for the hypocotyl and cotyledon explants in our study.
Strides made using soybean coty-node explants with one axillary meristem supported by a single cotyledon have so far not overcome the difficulties in developing a routine and reproducible in vitro regeneration protocol.