feb08 HELIOTROPIC HIGH-RISE - competition entry for skyscraper 08 an organic skyscraper, tracing the movement of the sun. project made in a group of two. > Tropism is a biological term referring to the orientation of an organism in response to an external stimulus, such as light, heat or gravity. The movement of a plant in response to the position and direction of the sun is called Heliotropism. Heliotropic plants track the motion of the sun from east to west, thus optimizing the process of photosynthesis.