You searched for: “geotropisms
geotropism (s) (noun), geotropisms (pl)
1. The response of a plant to gravity, as evidenced by growing patterns; such as, downward root growth and growth curvature.
2. Plant growth or movement in response to gravity: "Primary roots (tap roots) grow vertically towards gravity (positive geotropism) whereas primary shoots grow vertically away from gravity (negative geotropism), though the direction of shoot growth may also be modified by light."