2.81 Phototropism

2.81 describe positive phototropism of stems

Photo; light

Tropism; growth

Growth in response to light

And the positive suggests that it is towards the light

A stem-

Take the tip of stem, where uniform light coming from all directions hits it. This causes it to grow forwards and upwards

If we use the same stem but instead of the light coming from a uniform source, the light comes from a lateral source.

The plant bends in the growth towards the light. This is also another example of phototropism.

The light on the left side is the reason of the movement to the opposite (right) side. This is caused by a compound called auxin (a plant hormone) which causes more growth on both side resulting in the plant bending.