In nature, some lettuce plants of Compositae have a special skill - "meeting" guide. For example, Mongolian chrysanthemum, wild lettuce and grass hemp head on the grassland in northern China belong to this kind of plants.
Guide plant - wild lettuce
The leaves of these plants are very interesting, as if they are deeply attracted by gravity. They are vertical to the ground, rather than spreading out like the leaves of other plants and receiving the touch of the sun vertically. The direction of their leaves is always parallel to the north and south, so people call them "compass plants". Why are they so long?
Guide plant - Mongolian wind hairy Chrysanthemum
Two botanists in the United States studied them. They found that when these plants were planted in a large greenhouse with appropriate and comfortable temperature, the leaves were strangely no longer "guide"; Outside, even if they are planted in the shade of cool trees, they won't "guide"!
Polygonum capitatum
From this, the two scientists concluded that the leaves will "guide", which has nothing to do with gravity, but because of the sun! The hometown of "compass plant" is the grassland which is extremely hot and dry in summer. How to adapt to the environment here and survive better? Through instrumental measurement, botanists found that the "guide" of leaves was the best for the growth and development of plants. At noon, the sun shines strongly on the ground, and the leaves are also perpendicular to the ground. The sun is parallel to the leaf surface, and the leaf surface receives less sun. Think about it. If the leaves are perpendicular to the sun and the whole leaf surface is strongly exposed to the sun, it will make the leaf surface temperature very high and "fly" away how much water!
Guide tree
More interestingly, on the island of Madagascar on the east coast of Africa, there is a strange tree called "Candlestick tree", whose leaves can replace the compass to indicate direction. Rows of tiny needles grow on the trunk of this tree. Whether it grows in high mountains or Plains, fertile fields or grasslands, its needles always point to the south pole like a compass. Therefore, when residents call it a "guide tree". "Guide tree" provides convenience for tourists. It can point out the direction for people at any time. When local children go into the jungle to collect or play, they will not lose their way with its help, so people cherish this tree and pay great attention to its protection.
Guide tree - Indian homesick tree
There is also a strange and interesting tree growing in eastern India. Its branches and leaves are lush and evergreen. Its branches are always bent in one direction, and all the leaves are in one direction. Year after year, no matter the wind and rain, or the sunrise and sunset, we can't change the original direction. Therefore, people give it a good name and call it "homesick tree".
In the morning and evening, because of this position, the leaves can obtain higher benefits without wasting water "resources"!
Why do some plants "guide"
In nature, many plants are constantly changing the position of their leaves to adapt to the environment. Plants will not be ruthlessly eliminated by nature only if they adapt to the environment.