What makes plants bend toward light

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That information regulates their development so they maximize the light they can take in and use for photosynthesis. The process by which plant development is controlled by light is called photomorphogenesis. This bending toward light is called phototropism. Phototrophism is a response that causes house plants to lean towards the window and trees to branch over the road. Take a walk in the woods and look for fallen trees.

Auxins cause fallen trees to turn at their tips and grow upright again. This is a survival mechanism called phototropism. By orienting their leaves and stems towards light plants ensure that they will receive the maximum energy possible for photosynthesis. Phototropism is a complex hormonal and chemical response to light that is still not fully understood by scientists.

Phototropism is defined as the movement of plants towards light. It was first investigated by Charles Darwin. Using grass and grain seedlings he proved that the cells on the dark side of the plant the side away from a light source elongate causing the seedling to bend towards the light source. A plant hormone called indolacetic acid or auxin is responsible for making plant cells on the side away from light elongate. It is also responsible for making roots grow down into the soil called gravitropism.

Auxin triggers a chemical reaction which weakens cell walls allowing them to elongate and ultimately bending the plant towards light. Plants detect light with photoreceptors. Blue light absorbed by photoreceptors stimulates auxin to move laterally across the stem and leaves of plants to the side which is away from the light.