In nature, there is a kind of grass called Mimosa. If you gently touch Mimosa, its open feather-like leaves will be closed immediately, and then the whole leaf will hang down, showing a very shy appearance. Do you know why we intentionally or accidentally touch Mimosa, and it will "hang down"?

In fact, the phenomenon of mimosa folding its petiole and lowering its head is not because of shyness, but a reaction of plants after being stimulated and shaken. This reaction, known as nastic movement in biology, is the result of cell tension changes after mimosa is stimulated by the outside world.

mimosa has this special ability for a reason. Mimosa's hometown is in Brazil in tropical South America, where there are often strong winds and heavy rains. Whenever the first drop of rain hits the leaves, it will immediately close the leaves and droop the petiole to reduce the damage caused by the storm. This is a way for it to adapt to changes in external environmental conditions. In addition, this reaction of mimosa can also be regarded as a way of self-defense. When an animal touches it slightly, it closes its leaves, and animals are afraid to eat it again.

The leaves and petioles of mimosa have special structures. At the base of petiole and leaflet of compound leaf, there is a relatively enlarged part called leaf pillow. When the vibration is transmitted to the occipital lobe, the cellular fluid in the parenchyma cells in the upper part of the occipital lobe is discharged into the intercellular space, which reduces the swelling pressure of the cells in the upper part of the occipital lobe, while the intercellular space in the lower part of the occipital lobe remains the original swelling pressure. As a result, the small leaves stand upright, the two small leaves close, and even the whole leaf hangs down.

It has been studied that the leaves of mimosa will close within 1.188 seconds after being stimulated, and after a while, the small leaves will unfold again and the petioles will stand up. The recovery time is generally 5 ~ 11 minutes. However, if we continue to tease and stimulate its leaves one after another, it will feel "bored" and no longer react. This is because continuous stimulation makes the cell fluid that controls the opening and closing of the occipital cells lose and cannot be replenished in time.

[ families and forms]

Leguminosae, Mimosa. The stem base is lignified, which is perennial in subtropical areas. Mimosa has sharp thorns on its branches, erect stems and some vines. The leaves are pinnately compound, opposite, and there are 4 pinnate leaves on the total petiole. Each pinnate leaf consists of 14-18 lobules, and the lobules are oblong. The flowers are pale pink, and the flowering period is from July to October. The fruit is pod and the seeds are oblate.

[ Growth habit]

Mimosa is native to tropical South America, which likes warm and humid, is lax in soil requirements, likes light, but can tolerate semi-shade, so it can be used as indoor potted flowers for enjoyment. Mimosa leaves are small and arranged in a feather shape. When touched by hand, the leaflets will be closed after being stimulated. If the shock is strong, the stimulation can be transmitted to the whole leaf, and the total petiole will droop, and even it can be transmitted to adjacent leaves to droop its petiole, as if a girl is shy and droops her face, hence the name Mimosa. Are those really shy leaves?

Legend

There is a legend about mimosa.

Once upon a time, there was a very handsome young man who often went out fishing. One day, he saw an old man sitting by the river, talking to himself: "Fishing! Fishing! Fishing! Little fish never come, big fish come. "Said the big fish really swam to the old man. The young man said to the old man, "I'll learn fishing from you, ok?" The old man said, "there is nothing to learn about fishing. It seems that you are honest. I will tell you a secret. As long as you keep walking along this river bank, something good will happen." When the old man finished, he disappeared.

The young man was very happy and thought, I must have met a fairy, so I walked straight along the coast. It's dark, and we still go forward. There is a big bay full of lotus flowers in front of us. At the water's edge, the door of a family was open and the lights were lit. A young girl was sitting knitting silk. The young man asked before he left, "Excuse me, where is this place? I have lost my way." The silk weaver said, "This is the Lotus Village, and I am the Lotus Girl. If you are tired from walking, you can come in and have a rest." The young man sat for a while and was about to leave, but the lotus girl did not leave him and sent him out of the door. When the young man came home, he was infatuated and thought that this lotus girl must be a fairy. The old fisherman said that something good would happen when he walked forward. Maybe the fairy was going down to earth and wanted to marry her. The next morning, the young man walked along the river bank again, and when it got dark, he arrived at Lotus Village, where the lotus girl was still there, and his attitude was much more intimate than yesterday. She told the young man to take off his tattered jacket and mend it for him. The young man said, "I am alone!" " The lotus girl didn't hear it. Mend the clothes and send the young man out. It was midnight when the young man got home. He couldn't sit still and stood still. He just turned around and ran to the river, then went to Lotus Bay. When he saw a big lotus in the bay, he called for the lotus girl, and sure enough, the lotus girl came in waves. She said, "My father forbade me to associate with mortals. From now on, we shall not meet each other. The young man cried, crying very sadly. Lotus girl comforted: "As long as you are sincere, I will run away with you." The young man swore to heaven that he would never change his mind. Lotus girl took the young man to the deep forest in the horizon, and a small bridge went straight to the door of the hut. They crossed the bridge and entered the house. Everything in the house was fully furnished, and there was a loom. They got married there. The young man goes out hunting every day, and he can hunt some mountain rabbits and pheasants without much effort. In his spare time, he goes sightseeing in the mountains. Lotus girl is very hard, every day in addition to weaving silk, but also to the hills to plant mulberry.

year after year, the lotus girl's hair is not so bright, and her rosy face is not so lovely. The young man said to him, "You are too tired, people are getting old, so take a rest!" The lotus girl shook her head and said, "Look, how beautiful it would be if many barren hills became mulberry forests!" Lotus girl pulled a needle from her head and gave it to the young man, saying, "This needle is a treasure, which can subdue wild animals. You should use this precious needle to turn this uninhabited mountain area occupied by the killed animals into a paradise for the people. Note that this precious needle must not fall into the hands of others. " One day, the young man went hunting in the distant wild mountain and found a dark hole. He felt very strange. When he entered the hole, a tiger came at him. He pointed at the treasure needle given to him by the lotus girl and the tiger ran away. There is a gate in front. When you push the door open, the lamp is shining brightly. A young girl is sitting on the kang. She is much more beautiful than the lotus girl. The girl welcomes him and sits on the kang with food and drink, and they become close. Three days later, the girl said she wanted to go out to visit relatives, but she was afraid of being hurt by tigers and wolves. The young man said, "I have a treasure needle." Can defeat all beasts. " Then he handed the treasure needle to the girl. Who knows that as soon as the girl walked out of the hole, the hole was tightly closed, and the young man was forbidden in the hole. He remembered what the lotus girl said and regretted it too late. When the lotus girl saw that the young man didn't come back, she pinched her fingers and counted. She knew in her heart that the young man had become an ungrateful person and could not help crying. On second thought, let's save his life! She also has a treasure, which is the key to the mountain. Lotus girl reached the cave door, pointed the key to the mountain, the cave door was wide open, and the young man was ashamed and uneasy. The lotus girl said tearfully, "I never dreamed that you were such an ungrateful person!" They were on their way back when the girl came after them and shouted, "Young man, come back!" " Lotus girl said to the young man, "You can't look back at her. As long as you look back, you will die." The girl still shouted at the back: "Young man, think about it, where will you find a lovely beauty like me?" The young man was tempted and cast a glance back. The girl took advantage of the moment when his mind was shaken and swung the handkerchief, turning the young man into a weak grass growing on the ground.

the lotus girl stared at the grass, and the leaves of the grass were both in agreement, like crossing her hands to confess, and immediately hung down her petiole shyly to show her mistake. Lotus girl said, "Young man, you can still be ashamed and admit your mistakes." Later, people called it "mimosa" and it became a favorite grass. Agreed

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