hypocotyl

/hahy-puh-kot-l/US // ˌhaɪ pəˈkɒt l //UK // (ˌhaɪpəˈkɒtɪl) //

下胚轴,下胚层,下叶,下胚轴的

Definitions

n.名词 noun

1
Botany.
- : the part of a plant embryo directly below the cotyledons, forming a connection with the radicle.

Below the sheathing leaf is a narrow length which will be distinguished as the hypocotyl, and where growth is very active.
A lens focusses the light from O, on the hypocotyl, and that from O', on the tip of the cotyledon.
Contrary to generally accepted view the hypocotyl not only perceives but responds to light.
If the cotyledon be shaded and the light be permitted to fall on one side of the hypocotyl, no heliotropic curving takes place.
Hence considerable doubt may be entertained as regards the supposed absence of perception in the hypocotyl of Setaria.