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 ?
The shoots that were observed at low concentration treatments were presumably resulted from the development of two pre-existing cotyledonary nodal buds.
0 mg/L) of BA and Kn alone or in combinations were added to the culture bottles containing B5 basal media in order to assess their effect on In vitro morphogenesic responses of the Cotyledonary node.
with the sheath at the base of the cotyledonary stalk; "Sabal
The results obtained after 30 days of storage in a growth chamber were presented as followed: Cotyledonary nodes, axillary nodes and terminal apex of seedlings from in vitro germination were sowed on different culture media containing various hormonal combinations and described below in Material and Methods.
For multiple shoot induction, cotyledonary node (1-2 cm in length) obtained from 4 wk old seedlings.
In some taxa, the hyperphyll is inserted halfway into the hypocotyl, leaving a short but visible cotyledonary sheath and a short coleoptile (e.
Differentiation of cotyledonary somatic embryos from
globular precotyledonary and cotyledonary somatic embryos were seen only
However, there are no reports on cotyledonary leaf explants being used for regeneration studies.
After one month, those among them reaching the cotyledonary stage (5-10 mm, figure 1) were transferred to MS medium supplemented with 0.
Combining the data from these two sources, it is possible to develop a generalized scenario for collar development in temperate trees: in angiosperms, and a few gymnosperms, the collar originates from stem tissue immediately above the cotyledonary node.