Also found in: Dictionary, Medical, Wikipedia.


The portion of the embryonic plant axis below the cotyledon.



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.


References in periodicals archive ?
In contrast to the results obtained from epicotyl explants, the presence of cytokinin in the medium significantly affected the number of shoots formed from hypocotyl segments treated with BA at culture initiation and first subculture (F Test, P [less than or equal to] 0.
2 = moderate or severe yellowing of leaves with or without wilting, stunting, severe rot on taproot and secondary roots, crown rot with or without hypocotyls rot, and vascular discoloration in the stem,
1] BAP (D3), mature cotyledonary states were obtained that produced leaves, hypocotyls and secondary roots after being transferred to germination conditions.
curcas, yellow-green calli with friable texture were formed from hypocotyl segments cultured in 1.
Hypocotyl segments-derived explants were extracted from seeds germinated in Magenta boxes containing MT solid medium (40 mL) incubated in the dark for 20 d.
Nitric oxide stimulates seed germination and de-etiolation, and inhibits hypocotyl elongation, three light-inducible responses in plants.
Adventitious rooting in hypocotyls of sunflower (Helianthus annuus) seedlings.
CN12 is a multigerm, self-fertile population that segregates for genetic male sterility and hypocotyl color (75% red).
The hypocotyl showed more DNA agarose bands than hypocotyl groups under drought stress.