Mimosas: The Sensitive Creatures of the Plant World

It has immortalized its name in a common saying, as it possesses a very special characteristic. Everyone has heard or used the phrase "sensitive like a mimosa" to describe someone. So, what exactly makes this delicate plant so sensitive?

The scientific name for the plant we use as a houseplant is "Mimosa pudica," meaning "shy sensitive plant." We like to see it as highly sensitive, even bashful, because it loves to retract into itself. Like a seismograph, it reacts to the slightest tremor, and for this delicate creature, even a gentle touch is enough. The finely branched leaflets fold together, and then it even bows its "plant head" by bending its stem downwards. After a certain time, its inner calm seems to return, and it resumes its normal posture, as if nothing had happened.

Naturally, it's easy to compare this to human behavior. However, botanists simply see this cautious retreat as a protection against hungry creatures. This sensitive plant, of course, doesn't control its movement with muscular activity, as it has no muscles. But it does have leaf joints. Within their cells, there's a change in pressure. The plant tissue loses potassium, which releases water, leading to the tissue's "fatigue." So, it literally droops.

If you own a mimosa, you should avoid constantly provoking this reaction. For the plant, it's actual work and a process that expends energy.

This sensitive plant doesn't just display this behavior when touched. In the evening, it retracts in the same way, essentially "going to bed." In the morning, it wakes up fresh and lively. The reverse process occurs: the cells get a refreshing boost by absorbing potassium, which in turn fills them with water, allowing them to appear plump and upright again.

The mimosa found as a houseplant here displays pink to lilac colors and strikingly resembles a dandelion's seed head, which it transforms into to disperse its seeds. It's quite modest in its demands and blooms for a very long time.

The mimosas known for their cotton-soft yellow spherical flowers used as cut flowers are actually acacias, originating from trees and shrubs in tropical and subtropical regions. All of them belong to the pea family (Schmetterlingsblütler) and are characterized by the sensitivity described earlier. One species is even called the silk tree (Schlafbaum or silk acacia). In China, this plant is revered as a symbol of happiness. Its leaves and bark form the basis for medicines used to treat depressive moods and anxiety. Here in Germany, it's slowly gaining popularity as a container plant.

Several other plants also exhibit touch sensitivity. Native to our region is Lucky Clover (Oxalis tetraphylla), which is endowed with mimosa-like qualities. It retreats for the night by closing its leaves like an umbrella, only to cheerfully reopen them the next morning. Wood Sorrel (Oxalis acetosella) and Red Clover (Trifolium pratense) do the same. And if you see the young shoots of your pepper plant drooping limply in the evening, don't drown them with water; the plant is simply going to sleep.