hyponasty

[hahy-puh-nas-tee]

noun

Botany.

1. increased growth along the lower surface of a plant or plant part, causing it to bend upward.

hyponasty

/ ˈhaɪpəˌnæstɪ /

noun

1. increased growth of the lower surface of a plant part, resulting in an upward bending of the part Compare epinasty

Other Word Forms

• hyponastically adverb
• hyponastic adjective

Word History and Origins

Origin of hyponasty¹

1870–75; hypo- + Greek nast ( ós ) pressed close, compact + -y ³

Example Sentences

Hyponasty is the reverse, and implies increased growth along the lower surface, causing the part to bend upwards.*

From Project Gutenberg

Circumnutation modified through innate causes or through the action of external conditions—Innate causes—Climbing plants; similarity of their movements with those of ordinary plants; increased amplitude; occasional points of difference—Epinastic growth of young leaves—Hyponastic growth of the hypocotyls and epicotyls of seedlings—Hooked tips of climbing and other plants due to modified circumnutation—Ampelopsis tricuspidata— Smithia Pfundii—Straightening of the tip due to hyponasty—Epinastic growth and circumnutation of the flower-peduncles of Trifolium repens and Oxalis carnosa.

From Project Gutenberg

The movements thus induced result from a modified form of circumnutation; for, as we shall immediately see, an organ under the influence of epinasty does not generally move in a straight line downwards, or under that of hyponasty upwards, but oscillates up and down with some lateral movement: it moves, however, in a preponderant manner in one direction.

From Project Gutenberg

In order to ascertain whether the shoots of A. tricuspidata in straightening themselves under the combined action of hyponasty and apogeotropism moved in a simple straight course, or whether they circumnutated, glass filaments were fixed to the crowns of four hooked tips standing in their natural position; and the movements of the filaments were traced on a vertical glass.

From Project Gutenberg

This shows that there is some growth on all sides of the part, but more on the upper side in the case of epinasty, and more on the lower side in that of hyponasty, than on the other sides.

From Project Gutenberg