Are maple leaves red all year round?

The green change of leaves comes from chlorophyll. In addition to a lot of chlorophyll, leaves also contain pigments and nutrients such as lutein, anthocyanin and sugar.

In autumn, the weather turns cold, the temperature drops, the synthesis of leaf green is blocked, the green pigment in leaves decreases, and lutein, carotene and anthocyanin will be displayed. For example, anthocyanin is very bright red and lutein is yellow, so the colors of leaves in autumn are red and yellow in different shades, which is very beautiful. If we do an experiment, we cut a maple leaf in early autumn and put it in a dry place at home. A few days later, the water evaporated and the maple leaves turned into red leaves. If you put the cut green leaves in sugar water, they will turn red faster.

Anthocyanins only appear red in acidic environment and blue in alkaline environment. If the leaves themselves do not contain acid, they will not turn red. According to the determination, only the cell leaves in the leaves of a few plants such as maple and cotinus coggygria are acidic. These tree species will gradually change from green to red with the arrival of autumn. For most plants, there are few anthocyanins, or although there are many anthocyanins, the cell leaves are alkaline, so the leaves of these plants will not turn red because of the cold weather. China has a vast territory and a large latitude span, so the arrival of autumn is different.

Just entering September, when most parts of China are still in the late summer, the leaves of the Northeast Plain and Changbai Mountain have turned red. With the passage of time, the temperature gradually decreased, and most parts of China began to enter autumn, and the growth of red leaves gradually moved south. In 165438+ 10 and 65438+February, the leaves in the north have withered, and some areas in the south have been covered with red leaves.

References:

Popular science knowledge of Institute of Botany, Chinese Academy of Sciences