In the growing season of sunflower, you can always see the side of sunflower garden facing the sun. As long as you see which direction the sunflower's face faces, you can know which direction the sun is.

It's strange, why is the direction of sunflower facing the sun? Why don't other flowers do this? With this question, i query didn't know the reason until he learned the relevant information. Let's get to know each other.

Sunflowers facing the sun can be analyzed from biological science. It depends on what growth stage it is in.

Sunflower is really sunny from germination to disk flowering. During the day, its leaves and disk follow the sun from east to west, but not immediately. Botanists have measured that its disk direction is about 12 degrees behind the sun, which is 48 minutes. After the sun goes down, the sunflower tray slowly swings back, facing east at about 3 am, waiting for the sun to rise. Under the irradiation of sunlight, the auxin content on the back of sunflower increases, which stimulates the cells on the back to elongate, thus slowly rotating towards the sun. After the sun goes down, auxin is redistributed, and the sunflower slowly turns back to its original position, that is, the east.

However, once the disc is in full bloom, it no longer turns to the sun, but is fixed in the east. Why should we finally face the east instead of the other direction or upward? This may be the result of natural selection of sunflower.

Reproduction is good. Sunflower pollen is afraid of high temperature. If the temperature is higher than 30℃, it will be burned. So you can avoid direct sunlight at noon and reduce radiation. In the early morning sunshine, the flower tray helps to dry the dew condensed at night and reduce the possibility of being attacked by mold. Moreover, in the cold morning, under the sunshine, the sunflower disk becomes a warm nest, which can attract insects to stay there to help pollinate.

The auxin in sunflower receptacle is distributed in the backlight, so the stem on the backlight side grows faster and bends towards the light source.

Sunflower, named after the tip of its young plant in the early growth stage and the young disc in the middle growth stage, will obviously rotate with the sun. It is generally believed that the sunrise of sunflower is only related to light, but it is also closely related to gravity. As the sun rises, the east side of the green sunflower is exposed to the sun, resulting in a large distribution of auxin on the west side of its backlight. The cells on this side are elongated and grow rapidly in the longitudinal direction. As a result, the young stems bend to the slow-growing east side, that is, the top (disk) of the sunflower bends eastward in the morning. As the sun moves in the air and changes the direction of illumination, the top (disc) of sunflower also changes direction constantly, standing upright at noon and bending to the west in the afternoon, all of which show the phototropism of bending the stem top.

After sunset, the earth was dark, and the uneven distribution of auxin in plants caused by light disappeared. The uneven distribution of auxin in plants caused by gravity has risen from a secondary position to a dominant position. More auxin is distributed on the lower side (towards the ground) of the young stem of sunflower bent to the west, which makes the cells on this side divide and elongate, grow rapidly to the ground, and bend the stem to the upper side of the slow-growing back ground. As a result, the plants bent during the day are straight. Sunflower plants stand tall and straight at night, which is the natural response of sunflowers to gravity like other plants-the stems grow behind their backs and are upright. After learning some knowledge about sunflower growth, I believe you will have an epiphany like me.