There are a number of plants that grow towards sun. This activity of plants, to bend towards light, is known as phototropism. Usually, the upper portion of the plant i.e. the stem and the leaves look for a sunny spot and try to reach out. For instance, sunflower follows the path of the sun across the sky. This characteristic of the plant enables its leaves to receive the light energy required for the process of photosynthesis. This is an extremely important process for the plants to grow and reproduce. 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. The gene that causes plants to reach for t QCFP he sky has been cloned. To the scientists who found it, the big surprise is that part of the protein made by the gene is duplicated in many other organisms, from simple bacteria to humans. And while that protein section, called a “domain,” controls a plant’s tendency to bend toward light, in other organisms it governs responses to different environmental factors, such as changes in oxygen levels. You may have noticed that a houseplant grows toward the window and turns its leaves towards the light. It does this because light coming from the window side of the plant destroys the auxin in the shoots and leaves on that side, so that growth on this side slows down. On the shaded side of the plant there is more auxin, so growth on this side speeds up. The result is that the shoots and leaves are turned towards the light – maximising photosynthesis.