Do you know why Mimosa will close when touched? Why do sunflowers have sunflowers? In fact, this is caused by the perceptual movement of plants. So what is perceptual movement? Let's read on~
mimosa
What is the perceptual movement of plants: perceptual movement refers to the local movement of plants caused by the non directional external stimulation, and its response direction is independent of the stimulation direction. In many plants, the perceptual movement is a non growth movement caused by the change of cell turgor pressure, and some is related to growth.
Perceptual movement can be subdivided into: temperature sensitivity, sensitivity, shock sensitivity and night sensitivity. Let's take a look at the meaning of the four personalities.
Tulip blossom
Temperature sensitivity: growth movement caused by the change of temperature as a stimulus. Early spring flowering plants, the opening and closing movement of their flowers often belong to this category. For example, crocus flowers open in the day with high temperature, and the petals close completely in the night with low temperature. Sensitivity: growth movement caused by the change of light intensity as stimulation. Such as dandelion inflorescence closed at night and overcast. Tobacco is closed at light intensity, showing flowering at night. Sunflower.
Closed sensitisation of Mimosa: the plant movement caused by mechanical stimulation is called sensitisation. Mechanical stimulation includes vibration, burning, electric contact, sudden cooling and even light and dark changes. The most striking example of the sensational movement is the movement of Mimosa leaves. When part of the leaflets of Mimosa are stimulated by contact, vibration, heat or electricity, the leaflets are closed in pairs; if the stimulation is strong, the stimulation can be quickly transmitted through electric waves and chemicals, so that the adjacent leaflets are closed in turn, and can be transmitted to the base of the petiole all the way, so that the whole compound leaf is drooping; if the stimulation is strong, the leaflets of the whole plant are even closed, and the compound leaf petiole is drooping after a certain period of time After the treatment, the speed of restitution can reach 15 mm / s.
Why does Mimosa leaf droop? This is because the tissue structure of the upper and lower parts of the compound leaf mattress of Mimosa is different. The base of the total petiole and petiole of Mimosa is expanded, which is called leaf pillow. The cell wall in the upper part of the leaf pillow is thicker, while the cell wall in the lower part is thinner, and the cell gap in the lower part is larger than that in the upper part. When the external stimulus is transmitted, the permeability of cells in the lower part of the leaf pillow increases rapidly, and water and K + flow out into the cell space, so the swelling pressure of cells in the lower part of the leaf pillow decreases, and the tissue is weak; while the upper tissue remains tense due to different cell structures, and the petiole of compound leaves bends and droops from the leaf pillow. The results show that the water and K + flow out of the cells in the lower part of the leaf pillow is triggered by the stimulation of the electric wave, which promotes the release of sucrose from the phloem and leads to the decrease of the water potential of the apoplast. The mechanism of leaflet movement is similar to the above, except that the cell structure of the upper and lower parts of the petiole foot is just opposite to that of the leaf pillow at the base of the compound petiole. The movement of the leaf of the flytrap is also a kind of shock motion. Its leaf is specialized as a delicate insect catcher. When small animals step on the insect catcher, the shock motion is triggered, and the leaves are closed to capture the invading small animals.
Nocturnal sensation of sunflower and sunflower: the movement caused by the stimulation of the coming of night, the change of light and temperature, is nocturnal sensation. Some nocturnal movements are caused by uneven growth. For example, when the temperature of tulip rose from 7 ℃ to 17 ℃, the inner side of the petal base grew faster than the outer side, and the flower opened; on the contrary, the flower closed. For example, the inflorescence of dandelion and the petals of water lily open in sunny days and close in cloudy days or at night, while the opposite is true of tobacco and mirabilis. The nocturnal movement of flowers is conducive to flowering or insect pollination at appropriate temperature, and it is also the adaptability of plants to environmental conditions. However, there are also some nocturnal movements that are not growth movements, but movements caused by changes in cell turgor pressure. For example, some legumes (groundnut, soybean, Albizzia, etc.) close their leaflets at night, their petioles droop, and open again in the daytime.