The soil-protective role of specially-shaped plant roots

Some trees and shrubs which grow on steep slopes, abrupt banks alongside watercourses, or the sides of sunken roads, shape their secondary roots of the first order, and sometimes even the main root, in such a way as to develop in them a knee-like curvature, turning back into the more compact soil. This feature, here referred to as ‘edaphoecotropism’, is considered to be the results of a number of interacting physical of this phenomenon may be cited the response by roots to undesirable extreme topographic conditions of the site—some kind of ‘escape’ by the root into a more favourable environment—and a one-sided provocation of the root's growing portion, which produces variations in the distribution of auxin and thus the peculiar curvature of the root. This ‘edaphoecotropic’ orientation of the main root-branches in trees and shrubs is of importance in the safe anchoring of plants in the soil and, hence, increasing the stability of the earth or other slope or ‘cliff’.