1、 Causes of occurrence

1. As early as the end of the 18th century, a reasonable explanation has been made for this problem. The reason is that plants have phototropism and natural reactions in the body

2. Its main reason is that it is caused by elements in its own body - leaf yellow oxide, which will make the sunflower slowly rotate and move in the direction of the sun with the stimulation of the sun. Because the density of this material on the side without light is relatively low, and the density of this material on the side with light is relatively high, so after the sun rises from the East in the morning, it will gradually begin to move, and after the sun sets in the evening, it will return to its original position. But usually, it will stop rotating after flowering, and the direction is always the rising direction of the sun

3. This phenomenon is also caused by the earth's gravity. After the sun sets, the sky becomes dark. Without light, the hormone in its body decreases rapidly, and the originally curved branches become upright, so they return to the original state for growth. In this way, they grow back and forth, and change the angle in the direction of the sun