Tropism

Tropism is when an organism turns in direction due to external stimulus. There is hydrotropism where the plant growth turns to or away from moisture. Thigmotropism is the growth of the organisms from contact or touch. Heliotropism is when an organism grows toward the sun. Geotropism is when a plat grows toward the center of the earth.

Geotropism

Heliotropism

Thigmotropism

Hydrotropism