Heliotropism:

Geotropism:

Thigmotropism

-Tropism-

Phototropism:

Heliotropism is the motion of plants responding to sun. They either move away or towards the sun

This is the plant reacting to the earths gravity. If it is positive the plants roots are growing towards the earth. If it is negative, the roots grow away from the Earth.

This is when the plant reacts to light. Not just the sun. If it is negative, it grows away from light. If it is positive, it grows towards the light source.

Thigmotropism is where a plant grows toward the object it touches. For example, a vine.