cotyledon

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Related to Cotyledons: angiosperm, Monocotyledons, Dicotyledons

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 ?
Fruit a septicidal capsule, warty in Ledothamnus, seeds with [+ or -] isodiametric to elongate testa cells; embryo with 2 cotyledons .
To some of these animals, the cotyledons represent a more attractive energy reward than does the fruit pulp.
The decrease in o-diphenols with increasing pod storage might be due to the reduction in pulp volume with an increase in aeration which might have enhanced the activities of diphenolase in the cotyledons to oxidize the o-diphenols to o-quinones during fermentation.
Plants with two cotyledons are called "dicots," and those are the leaves that the scientists studied.
The two cotyledons have entire margins, the two pairs of eophylls ("primarblatter") have dentate margins, and above them, there is an abrupt change to trifid spiny leaves on the main axis.
This is because the caterpillars produced a hole in the pericarp of the fruit to reach the seeds that indeed they did eat, thus eliminating the cotyledons and the viscin.
In pigeonpea, a few protocols on regeneration are reported (Eapen and George, 1993; Somatic embryogenesis was induced from mature cotyledon explants of two pigeonpea genotypes cultured on MS medium supplemented with different concentrations of 2, 4-D and Thidiazuron (TDZ).
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However these were found to be higher in lower concentration of sewage water treated cotyledons.
The ability of seedlings to cope with herbivory is likely affected by seed size, the presence or absence of cotyledons, and the time elapsed since germination (Bonfil 1998).