grav-eh-TROP-izm A plant's growth response toward or away from gravity. 578

Gravitropism [or geotropism] is a turning or growth movement by a plant or fungi in response to gravity. Charles Darwin was one of the first to document that roots show positive gravitropism and stems show negative gravitropism. That is, roots grow in the direction of gravitational pull (i.e., downward) and stems grow in the opposite direction (i.e., upwards).