• (n.) The tendency of organs (as roots) of plants to assume a position oblique or transverse to a direction towards the center of the earth.
Di`a·ge·ot'ro·pism noun (Botany) The tendency of organs (as roots) of plants to assume a position oblique or transverse to a direction towards the center of the earth. 
diageotropism 1. The tendency of a sessile organism (leaf or flower that has no stalk but is attached directly to the stem), or structure, to grow horizontally to the ground or perpendicularly to the line of gravity; such as, a tree branch or root. 2. A response of a plant to gravity in which a part of the plant adopts a horizontal position. 3. T...
diageotropic tendency or growth.