epinasty

But a portion near the blades of the cotyledons is after a time acted on by epinasty and curves downwards, for the sake of emerging in the form of an arch from the ground; it subsequently straightens itself, and is then again acted on by apogeotropism.

With the flower-peduncles of Oxalis, epinasty causes them to bend down, so that the ripening pods may be protected by the calyx from the rain.

These classes of movement consist of those due to epinasty and hyponasty,—those proper to climbing plants, commonly called revolving nutation,—the nyctitropic or sleep movements of leaves and cotyledons,—and the two immense classes of movement excited by light and gravitation.

At the same time the loop became open and was thus reconverted into a hook, and this apparently was effected by the geotropic movement of the apex in opposition to epinasty.

On the other hand, from observing the effects of tying a shoot downwards, so that the rectangle faced upwards, we are led to believe that the curvature is partly due to epinasty.