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Sleep paper
In the past, we only knew that people and animals would sleep in order to eliminate fatigue after a busy day, adjust their physiological functions and meet the next day's life with abundant energy. By chance, I found that plants can sleep.

A few days ago, my family planted several potted flowers, and some humble tamarind grass grew in the soil at the root of each flower. Their bright green leaves with big three petals and small six petals are evenly scattered in the flowerpot, which also adds a little beauty to the potted flowers. After winter, in order to prevent potted plants from being attacked by cold current, my father moved these flowerpots into the house.

Late one night, I accidentally saw the leaves of Ceratophyllum flagelliforme drooping, as if it had faded, as did other pots of Ceratophyllum flagelliforme. I think these grasses may have died because they could not adapt to the indoor environment. When I got up the next morning, the "withered" amaranth leaves scattered again last night. What's going on here? I decided to solve the mystery. In the next few nights, I often observe carefully by the flowerpot and write down my observation diary.

After 7 o'clock in the evening, the leaves of Salvia angustifolia began to droop, slowly closed into a triangle, and tightly "hugged" the petiole, like a folded umbrella; 10 point, all leaves are closed; After dawn, these closed leaves open again to welcome the rising sun, and use light energy to make water and carbon dioxide become organic matter again. Therefore, I conclude that Ceratophyllum can also "sleep". Why does grass sleep like people? I searched the relevant information and finally uncovered the secret.

It turns out that this form of exercise, which changes with the light and dark cycle of day and night, is caused by the stimulation of the arrival of night, also known as "night sensation exercise" or "sleep exercise". Many plants have this kind of exercise. Leaves such as peanuts, soybeans, acacia, mimosa, etc. stretch against the sunrise during the day and close in pairs at night. The nocturnal movement of Ziziphus jujuba shows that the leaves will face down at night and face up during the day.

This nocturnal exercise is caused by the difference of auxin content on the upper and lower sides of their petioles with the change of day and night. During the day, when the auxin produced in the leaves moves to the petiole under the sunlight, it is mostly concentrated in the blade part connected with the sieve tube at the lower side of the petiole. Because this part of auxin has a high concentration, it grows faster and leaves face up. At night, the content of auxin in the upper petiole is higher than that in the lower petiole, which accelerates the growth of the upper petiole, leads to the downward leaves and prevents water loss.

The secret of Suaeda salsa's diurnal variation was finally revealed. This made me realize that there are many strange flowers and plants around us. As long as we observe them carefully, think carefully and study them carefully, we can know them and uncover the mystery.