Why are mimosa "shy"? The petiole base and compound leaf base of mimosa have an enlarged part, which is called leaf pillow. There are vascular bundles in the center of occipital lobe and many parenchyma cells around it. In normal times, each cell is filled with enough water, thus expanding, making the occipital upright, so the leaves stretch, but once stimulated, the water contained in the occipital cells flows into the intercellular space, so the occipital becomes soft and the leaves close and droop. Mimosa's hometown is in tropical America, where there are often storms. This "shy" characteristic of mimosa is very beneficial to protect itself from wind and rain. It is also like a shy girl standing at the window. When she meets a stranger, she immediately closes the window, which is quite interesting and ornamental.
The whole plant of Mimosa mimosa has little toxicity, and it is used as medicine to soothe the nerves. Fresh leaves can be mashed and applied externally to treat herpes zoster. Originated in tropical America, it is now widely distributed in tropical regions of the world, and produced in Yunnan, Guangxi, Guangdong and other provinces and regions in China.
Mimosa is a perennial herb, but it is not as weak as ordinary herbs. Its stem branches from the basal part, which is upright or inclined, about 20 to 50 cm high, all with long soft hair and sharp thorns. The leaf is palmately compound and consists of four pinna. There are many small leaves on each feather, which is different from ordinary palmately compound leaves. There is an enlarged structure at the base of the total petiole, which is called "leaf pillow" near the base of the petiole.
The flowers of mimosa are very special. Its purplish red or pink flower ball is actually not a flower, but an inflorescence composed of many small flowers. If you carefully separate each small unit on the ball, you can see that each small unit has four divided petals, four long stamens and a pistil. It turns out that every small unit is its flower.
After the flowers of mimosa are in full bloom, most of them will form pods, so the mimosa fruits we see are also densely spherical. Each pod has three or four nodes and the surface is hairy. When the pod matures, it falls off from one section to another, leaving only the empty shelf formed between the sections, which looks very interesting.
If you touch it gently, its open pinnate compound leaves will close immediately, and then the whole leaf will hang down again, showing a "shy" appearance, hence the name mimosa.
Why do mimosa droop when we touch it intentionally or unintentionally?
This phenomenon of closed leaves and drooping petioles of mimosa is not "shy", but a reaction of plants after being stimulated and shaken. This reaction, called nasal movement in biology, is the result of the change of cell tension after the mimosa is stimulated by the outside world.
It turns out that the leaves and petioles of mimosa have special structures. There is a relatively enlarged part on the petiole and leaflet base of compound leaves, which is called leaf pillow. Leaf pillow is the most sensitive to stimulation. Once it touches the leaf, the stimulus immediately spreads to the leaf pillow at the base of the petiole, so that the two small leaves are closed, and the tactile force is strong, not only to the leaf pillow of the lobule, but also to the leaf pillow at the base of the petiole soon, and the whole petiole droops. Why is this happening? This is because there is a large vascular bundle in the center of occipital bone, which is surrounded by parenchyma and has many intercellular spaces. 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 original swelling pressure is maintained in the lower intercellular space. As a result, the leaflets stand upright, the two leaflets are close together, and even the whole leaf hangs down. It has been studied that mimosa leaves will close within 0.08 seconds after being stimulated. After stimulation, the conduction speed is also very fast, and the highest speed reaches 10 cm per second. After the stimulation, after a while, everything slowly returned to normal, the leaflets unfolded again, and the petiole stood up. The recovery time is generally 5- 10 minutes. However, if we continue to tease and stimulate its leaves one by one, it will feel "bored" and no longer respond. This is because the continuous stimulation makes the cell fluid in the occipital lobe cells lose and cannot be replenished in time.
This special skill of mimosa has its historical roots. Its hometown is Brazil in tropical South America, where there are often strong winds and heavy rains. Whenever the first drop of rain hits the leaves, it immediately closes the leaves and hangs down the petiole to avoid the damage of the storm. This is an adaptation to changes in external environmental conditions. In addition, the movement of mimosa can also be regarded as a way of self-defense. When the animal touched it lightly, it closed the leaves, and the animal dared not eat any more.
Mimosa is not a native of Taiwan Province Province, but its hometown is far away in South America. Taiwan Province Province was introduced by the Dutch in the17th century, and now it can be seen in open spaces, riverbeds, wasteland, playgrounds and other places all over the province. Especially in central and southern China. Respondents: Enthusiastic users | 2011-4-10/3: 31| reported.
There are many potted plants on my balcony, including chlorophytum, lily, poinsettia and Phalaenopsis … but I like ordinary mimosa best.
From a distance, it looks like a small tree in the picture, with its branches stretching out. It's even weirder when you look closely. The thin leaves on each branch have no veins! As long as you touch its branches, it will be wrapped shyly, just like a shy little girl. If you touch its branches, it will droop immediately, as if it were suddenly broken by a strong wind, but when you look at it again a few minutes later, you will be surprised to find that the mimosa has stretched out its small body and restored its previous appearance, and the color of its leaves seems to be greener than before.
One day, I found a small pink flower like a fluffy ball growing next to the leaves of a mimosa. I wanted to feel what it was like, but I didn't expect to turn it off. It looks like a cute little thing that people don't want to touch.
I'll tell you a little secret: mimosa will grow faster after listening to music. What a wonderful plant!
But up to now, I still don't understand why mimosa closes shyly when touched, just for fun, but I will continue to observe carefully and try to uncover this mystery as soon as possible!
In a small flowerpot on my balcony, there is a humble mimosa.
The leaves of mimosa are oval, as light as small feathers and a little rough to the touch. This tiny stem is so fragile that a drop of water can bend it. When the wind blows, mimosa swings with the wind, just like a dancing girl. Its flowers are in full bloom, and the oval petals are purple. How like a little fluffy ball!
Once, I accidentally met a mimosa, and its green leaves were immediately put away and its petiole fell off. I squatted down curiously and found that after a while, the leaves of mimosa opened again and the petiole changed back. At this time, a question came to my mind: Why does the mimosa put away its leaves after being touched?
I immediately moved out the extracurricular study materials, and after some careful searching, I found the answer: It turns out that there is an enlarged organ called "leaf pillow" at the base of the petiole of mimosa, and there are many parenchyma cells in the leaf pillow, which is very sensitive to external stimuli. Once it touches the leaves, the stimulation will be immediately transmitted to the occipital bone. At this time, the cytosol in parenchyma cells began to flow into the intercellular space, which reduced the expansion ability of cells, led to the decrease of intercellular pressure in the lower occipital region, and the phenomenon of closed leaves and drooping petioles appeared. After a minute or two, the cell fluid gradually flows back to the leaf pillow, so the leaves return to their original appearance.
The above phenomenon of Mimosa leaves is the result of its long-term adaptation to the natural environment in the process of system development. Mimosa lives in tropical areas, where there are many storms. Therefore, in order to protect itself in the long-term harsh natural environment, whenever a storm comes, it immediately closes its leaves to protect itself from the storm, thus gradually forming this unique physiological phenomenon.
I thank mimosa, which brings me curiosity. I want to study hard and use this "key" to explore the mysteries of the plant kingdom and explore more knowledge.