Coordination in plants

Phototropism

Growth towards or away from light

Directional Stimulus

A stimulus only from one direction

• Sunlight hitting a plant from one side → The plant bends towards the light due to phototropism.

• Gravity pulling roots downward → Roots grow downward in response to geotropism.

Negative tropic response

The plant grows away from the stimulus

Geotropism

Growth towards or away from gravity

Stimulus

Something that causes a response or change

• Touching a Mimosa pudica (sensitive plant) → The leaves close as a response to touch.

• Temperature drop in winter → Trees shed leaves in response to cold temperatures.

Tropism

A growth movement in response to a directional stimulus