apogeotropism

In whatever position the seed may be embedded in the earth or otherwise fixed, both legs of the arch bend upwards through apogeotropism, and thus rise vertically above the ground.

In the morning, up to about 11 A.M., they moved in zigzag lines towards the light; and at night they again became almost upright through apogeotropism.

This movement no doubt was due to epinasty, aided by apogeotropism, for the closed lobes of a very young leaf on a plant which had been placed horizontally, moved into nearly the same line with the petiole, as if the plant had stood upright; but at the same time the lobes curved laterally upwards, and thus occupied an unnatural position, obliquely to the plane of the foliaceous petiole.

Except when already standing vertically upwards, both legs of the arch are acted on from the earliest period by apogeotropism.

He would first endeavour to get his arched back upright, wriggling at the same time in all directions to free himself a little from the surrounding pressure; and this may represent the combined effects of apogeotropism and circumnutation, when a seed is so buried that the arched hypocotyl or epicotyl protrudes at first in a horizontal or inclined plane.