Shame grass. Who knows?

Introduction of Mimosa: Mimosa is a kind of low herb growing on the sunny grassland, also known as "Mimosa", "flowers afraid of itching" and "grass afraid of wife". It is a leguminous plant with alternate leaves and bipinnately compound leaves. The total stalk is very long, and the base expands into a leaf pillow, that is, there is a hypertrophy part at the base of the small feather, stem and petiole of mimosa, which is called a leaf pillow. The whole plant has bristles and spikes, about 20 to 60 cm high. The leaves of mimosa have quite long petioles, and the front end of the petiole is divided into four feather shafts, each of which has two rows of oval small feathers. Flowers bloom after midsummer, and pink flower heads are scattered on the grassland, like fluffy balls. As soon as you touch it, it gets shy. First close the little feathers one by one, then close the four feather shafts, and then the whole petiole hangs down. Each flower has inconspicuous sepals, four petals and four stamens. The pod has two to five nodes, each node contains a seed, and the surface is covered with fluff. When it matures, it falls off the node, leaving only an empty skeleton, which is another miracle.

Second, the principle and mechanism of shame:

The movement phenomenon of plants is usually caused by the change of intracellular expansion pressure. Most mature plant cells have a large vacuole. When the vacuole is filled with water, it will press the surrounding cytoplasm tightly against the cell wall, giving the cell wall a pressure, which is the expansion pressure. The pressure of expansion makes the cell wall tense, just like a balloon filled with air. The concentration of organic and inorganic substances in vacuoles determines the osmotic pressure, which can determine the diffusion direction of water. When the vacuole concentration increases, the osmotic pressure increases, and water diffuses from outside the cell into the vacuole, which increases the swelling pressure of the cell and makes the cell swell. On the contrary, cells will shrink. This process can only cause slow movement, such as the opening and closing of stomata, but it can also cause quite fast movement when the semipermeability of cell membrane suddenly changes. Chloride ions are transported to the inside of the cell, and cations are transported to the outside of the cell, so that a certain potential difference is maintained between the cell membrane and the adjacent area, which is called electrostatic potential. When the external stimulus exceeds a certain limit, the differential permeability will suddenly change, and a large number of calcium ions will flood into cells, while potassium ions will do the opposite, which will increase the potential in the membrane and even become positive potential, thus generating action potential. This phenomenon is called depolarization. The action potential will be transmitted. When the cell reaches the action potential, that is, depolarization occurs, the differential permeability of the cell membrane disappears, and the water originally stored in the vacuole is instantly discharged, so that the cell loses its expansion pressure and becomes soft. Several vascular bundles of the petiole are combined into a large pipeline in the leaf pillow, which is convenient to contain the water discharged from the leaf pillow. When we meet the leaves of mimosa, the cells in the occipital leaves are stimulated to depolarize, and the cells immediately lose moisture and expansion pressure, so the occipital leaves become soft, and the feathers lose the support of the occipital leaves and close in turn.

In the lower part of the occipital lobe, there are some sensory cells with extremely low resting potential, which are particularly vulnerable to stimulation. As long as it is touched slightly, it will immediately release water, make the petiole droop, and cause the shame of mimosa. Other Albizia Albizia of Mimosa also gather feathers at night, just like sleeping, which is due to the cell swelling and pressure change of occipital bone. In addition, when the leaves are stimulated, the mesophyll cells near the middle rib lose their expansion pressure and make the leaves close. At this time, the bristles at the edge of the leaves also play their blocking role, so the falling insects can't break free.