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.
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The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

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.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

cotyledon

[‚käd·əl′ēd·ən]
(botany)
The first leaf of the embryo of seed plants.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

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
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
References in periodicals archive ?
During the initiation phase, swelling of the explants was observed after six weeks of culture in induction medium and type II calli appeared on the surface of the immature cotyledons (Fig.
On the 15th DAS, germination began with the protrusion and elongation of the cotyledon petiole, with successive differentiations into primary root, leaf sheath, emerging on the side opposite to the one from where the root emerged, and the first eophyll.
Conclusion: It is concluded that cotyledon explants incubated on MS medium containing 4.0 mg/L TDZ plus 4.0 mg/L NAA can produce abundant amount of callus.
However, in most cases, regeneration from adult material has limited practical applications, and most Pinus micropropagation protocols reported in the literature are based on organogenesis from the cotyledons of seeds germinated in vitro (ALONSO et al., 2006; ALVAREZ; MAJADA; ORDAS, 2009; HUMANEZ et al., 2011; STOJICIC et al., 2012).
However, the cultivation of explants in flasks with lower gas exchange was more effective in callus induction than regeneration, and hypocotyls were more effective than cotyledons in morphogenesis induction.
There were no significant differences between the AUDPCs of the treatments or controls for the cotyledons. Inagaki et al.
The results of the present study indicated that, among the studied factors and their interactional effects on the percentage of callus formation, only explants effect was significant, so that cotyledon explant showed a superior response compared to hypocotyl explant (Table 4).
Moreover, in virulence seedling tests to isolates of races 714 and 704, certain sunflower plants (1-3) per replication for H3 and H4 produced no sporulation on cotyledons and leaves.
Total vitamin C content ranged from 20 to 147 milligrams (mg) per 100 grams of cotyledon fresh weight, depending on which plant species was being tested.
Tasaka, "The NAC domain mediates functional specificity of CUP-SHAPED COTYLEDON proteins," Plant Journal, vol.