Hypocotyl

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hypocotyl

[′hī·pə‚käd·əl]
(botany)
The portion of the embryonic plant axis below the cotyledon.

Hypocotyl

 

in sprouting plants, the section of the stem extending from the root collar (the zone between the main stem and the root) to the place of attachment of the cotyledons. In the embryo, the hopocotyl is the rudimentary stem. The sprouts of some plants have an elongate hypocotyl that bears assimilative cotyledons. This type of aboveground germination characterizes hornbeam. In other plants the hypocotyl is underdeveloped, and the cotyledons do not appear on the surface. Such underground germination is typical of the pea and the oak.

The anatomical structure of the hypocotyl retains its embryonic character. It may give rise to adventitious shoots, roots, or leaves (when the apex of the epicotyl is removed, as in cyclamen). In some plants the hypocotyl becomes the repository of nutrients (for example, the tuber in cyclamen). In many root crops, including the turnip, carrot, and sugar beet, the hypocotyl consists of the fleshy part of the storage organ, which is found between the stem base and the root proper.

L. V. KUDRIASHOV

References in periodicals archive ?
Caption: Figure 2--Induction of phaseolin production in common bean (Phaseolus vulgaris) hypocotyls by different concentrations of green propolis ethanolic extract (EEP) (A).
Chinese scientists prepared soy milk from germinated soybean--Glycine max (L.) Merrill--that featured different hypocotyl lengths.
Effect of auxins and plant oligosaccharides on root formation and elongation growth of mung bean hypocotyls. Plant Growth Regulation, 46, 1-9.
Gene transformation potential of commercial canola (Brassica napus L.) cultivars using cotyledon and hypocotyl explants.
Seedlings (Figure 1A and C) are phanerocotylar and epigeal, with axial root, collet visible for presenting slight constriction, hypocotyl long, cylindrical and green, and epicotyl relatively short, cylindrical, green, hairy, with scale like leaves.
Caption: FIGURE 3: Effect of BA treatment, with or without IBA or NAA, on shoot regeneration rate in nodal segments from hypocotyls of Aspidosperma polyneuron.
The concentration corresponding to the lower [IC.sub.50] values, obtained with cultivar BR-1 in order to inhibit the development of hypocotyls or rootlets, was used for the comparative analysis of extracts from other cultivars.
[31] determined the macamide contents in maca samples from different origins and found that N-benzyl hexadecanamide was the predominant macamide which ranged from 0.00537 to 0.0711 mg/g dry hypocotyls which was similar to our report.
[GAI.sub.1] inhibits elongation of Arabidopsis hypocotyl cells under dark and light conditions [17].
One month after seed culturing, when grown plantlets were about 5 cm in height, about 0.5 cm of each explant including hypocotyl and cotyledon was prepared.
Influence of growth regulators on callus induction from hypocotyls of medium staple cotton (Gossypium hirsutum L.) Cultivar Barac B-67.