heliotropism

noun

1. heliotropic tendency or growth.

noun

1. the growth of plants or plant parts (esp flowers) in response to the stimulus of sunlight, so that they turn to face the sun

1. The growth or movement of a fixed organism, especially a plant, toward or away from sunlight. Heliotropism can be easily seen in sunflowers, which slowly turn their large flowers so that they continually face the sun.