Growth of a plant in response to a light stimulus is known as

The growth of a plant in response to a light stimulus is known as Phototropism. Phototropism combines "photo" (light) and "tropism" (turning or growth toward a stimulus). Plants can display either positive phototropism (growing towards the light source) or negative phototropism (growing away from the light source). For instance, stems generally show positive phototropism, whereas roots often show negative phototropism.