diatropism

A *tropism in which the plant part is aligned at right angles to the direction of the stimulus acting on it. A diatropic response to gravity (diageotropism) is seen in the horizontal growth of rhizomes and stolons. A diatropic response to light (diaphototropism) is often seen in the positioning of leaf blades at right angles to the incident light. Compare orthotropism , plagiotropism.