Phototropism

This is a picture of a leaning plant. This plant has been affected by phototropism. Tropism is a growth response that results in plant organs leaning towards or away from any stimuli. In phototropism, the stimuli is light. The shoots of plants usually result in positive phototropism (towards the light), while the roots generally result in negative phototropism (away from the light). The cells on the plant that are farthest from the light contain a hormone chemical, auxin, that reacts when phototropism occurs. This causes the cells on the darker side of the plant to elongate faster than the cells on the brighter side, resulting in a leaning appearance. Phototropism is most often observed in plants, but can also occur in other organisms, such as fungi.