Examples from the Web for hypocotyl
A lens focusses the light from O, on the hypocotyl, and that from O', on the tip of the cotyledon.
Below the sheathing leaf is a narrow length which will be distinguished as the hypocotyl, and where growth is very active.
The part of the stem below the cotyledons (hypocotyl) commonly plays the greater part in bringing this about.
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.