Does the sensitive plant (Mimosa pudica) close when touched, and will it bloom and set seed in summer?

Mimosa pudica is a perennial herb or subshrub of the Fabaceae family. It gets its name because its leaves react to heat and light and close immediately when touched by external force. So will the delicate Mimosa pudica bloom and set seed in summer? According to Ms. Li, manager of a flower shop in Changsha, Mimosa pudica blooms in midsummer, generally flowering between July and October on the Gregorian calendar. Among the green grass, the pale purplish-pink flowers, downy and soft, look especially bashful, while the slender branches and leaves set off the plump, round blossoms, making them even more charming and vivid. After flowering, Mimosa pudica forms pods in autumn, which contain seeds that drop off between the segments when ripe.

Appendix: Why do the leaves of Mimosa pudica fold up as soon as they are touched

When the leaves of Mimosa pudica are touched, they immediately fold together. The greater the force of the touch, the faster they close, and the whole leaf droops as if listless. The entire action is completed within a few seconds. The leaves and leaf stalks of Mimosa pudica have a special structure. At the base of the leaf stalk and at the base of each small leaflet of the compound leaf, there is a relatively swollen part called the pulvinus. The pulvinus is most sensitive to stimuli. Once a leaf is touched, the stimulus is immediately transmitted to the pulvinus at the base of the leaf stalk, causing the two small leaflets to close. With a slightly greater touch, the stimulus is not only transmitted to the pulvinus of the leaflets but also quickly reaches the pulvinus at the base of the leaf stalk, and the entire leaf stalk droops. Why does this happen? This is because there is a large vascular bundle in the center of the pulvinus, and around the vascular bundle is filled with parenchyma tissue that has many intercellular spaces. When vibration is transmitted to the pulvinus, the cell sap in the parenchyma cells of the upper half of the pulvinus is discharged into the intercellular spaces, reducing the turgor pressure of the cells in the upper half of the pulvinus, while the intercellular spaces of the parenchyma cells in the lower half still maintain their original turgor pressure. As a result, the small leaflets stand upright and the two small leaflets fold together, or even the entire leaf droops. Some people have done research showing that within 0.08 seconds after Mimosa pudica receives a stimulus, its leaves close. After stimulation, the speed of transmission is also very fast, reaching a maximum speed of 10 cm per second. After the stimulus, after a short period, everything slowly returns to normal, the leaflets unfold again, and the leaf stalk stands up again. The recovery time is generally 5-10 minutes. However, if we continue to tease it and stimulate its leaves continuously, it develops a feeling of “annoyance” and no longer reacts at all. This is because continuous stimulation causes the cell sap in the pulvinus cells to be lost and unable to be replenished in time.

This special ability of Mimosa pudica has a certain historical origin. Its original home is Brazil in tropical South America, where there are often strong winds and heavy rains. Whenever the first drop of rain hits a leaf, it immediately closes its leaflets and droops its leaf stalk to avoid the damage caused by violent storms. This is an adaptation to changes in external environmental conditions. In addition, the movement of Mimosa pudica can also be seen as a form of self-defense. As soon as an animal touches it, it folds its leaves, and the animal no longer dares to eat it.

Appendix 2: Why do humans feel shy?

Shyness is actually a kind of fear. Worrying that one's shortcomings will be exposed in the sunlight and make others look down on oneself, one does not dare to express oneself. The more one expresses oneself, the more afraid one feels. Ordinary people also have feelings of fear. Shy people are mentally sensitive and overly afraid. They may experience normal reactions such as blushing and a faster heartbeat.