Plants respond to various stimuli, be it due to the force of nature or deliberate sensitivity. They adjust their size or shrink and react to these senses, which has brought attention and curiosity. This response is often tongue twisted as thigmorphogenesis in the scientific literature.
The most commonly known plant that visibly reacts and is popular is the Touch-Me-Not plants. They’re also called sensitive plants, though scientifically, they’re referred to as the Mimosa Pudica. The Venus Fly-trap is another aggressive example of a plant that responds to the touch of anything.
Are there more plants like this in the floral kingdom? What are they, and what sort of reaction do they give when touched? Find out about these plants in this article.
Plants That Close When Touched
Many plants react to these natural or deliberate factors that trigger their sensitivity. Here is a list of them all.
1. Mimosa Pudica
By far, it the most popularly known plant that responds so actively to touch. When the leaves of the pudica plant are touched, they tend to fold inward and flap closed. It takes anywhere between 5 to 30 minutes for them to revert to their original position.
This rapid change occurs due to the change in turgor pressure, which is defined by the amount of pressure that water is putting against the cell wall of the leaf. The chemical structure is also slightly altered, as a result of which the plant flaps itself over and closes up.
The reason for this behavior that many botanists have explained is that the Pudica tries to shield itself from herbivorous insects, leeching loss of nutrients or heat and weight. This change is optimized by the plant to create protection and energy production.
2. Bryonia Dioica
Often known as the red or white bryony, this English mandrake is a sensitive plant in the cucumber family. While the plant itself is dangerous and produces toxic chemicals when taken as a juice, the seeds, in contrast, are extremely helpful.
The Bryonia is also a sensitive plant that reacts visibly to touch, be it physiological or mechanical stimulus. The vines tend to curl and coil due to the lack of jasmonic acid in the plants.
3. Mimosa Pigra
The name sounds familiar to you because Mimosa Pigra is the giant version of mimosa pudica. It is a tree in the genus of mimosa and responds to change just as the pudica does. They are instantly responsive to touch and fold into themselves at night.
There is a considerable difference in their appearances too, which include its large size, longer stems, and bigger pods. Their leaves have more leaflets/pinnae than the pudica does. Their flowers and seeds are bristling with prickles.
They are large, intrusive plants that form large thickets of their distribution. The catclaw mimosa, as the mimosa pigra is sometimes called, blooms flowers that are lilac or pinkish white.
4. Venus Flytrap
Arguably, the Venus Flytrap is the most fabled plant that is a carnivore. It opens its largemouth to the touch of food, which includes insects, small birds, snakes, and more.
The bi-lobed leaves combined with the shapes of the large margins are often mistaken by the prey to be harmless. An unsuspecting prey would land on those, and the Venus Flytrap would close up in less than a second.
The Venus Flytrap reacts to triggers differently than most responsive plants. When the prey comes in contact with the leaves, its movement must trigger more than 3 of the hairs. It is then that the trap closes in mere seconds. Otherwise, it would have taken longer for the plant to trap.
Bladderwort of the Utricularia genus is a carnivorous plant that might look like haloed snow from a distance, where in reality, it contains sacs to trap its prey.
These bladderwort plants are usually found by the water, and interestingly, they have no roots. They have a horizontal, floating stem with divided leaves that give them their unique appearance.
Bladderworts’ sacs are under the water and use that to their advantage. These bladders create a low-pressure area in the traps. The water around the bladder helps the plant to immediately suck the prey in when triggered.
Monstera vine belongs to the Araceae family of flowering plants and is often affectionately called the “Swiss Cheese Plant.” This is due to the strange appearance of the leaves; the leaves are perforated, and they look like someone has punched holes in them.
The monstera is appropriately named due to its abnormality. They are immensely large plants that are also grown indoors. Even outdoors in the wild, these plants show gradual change to the shadows, often resulting in skototropism.
Monstera plants have a strange tendency to bend towards darkness. They grow in, searching for the shadow of any tree. Once they touch the tree, they begin to cling to it and show a drastic change in its development. This is most often due to the increase in light, which leads to a better photosynthetic process.
Most plants’ roots grow upward and above the ground or under the ground to collect water and minerals. This is characteristic and allows the element of gravitropism to be applicable. The Arabidopsis, however, tends to reject that. Its gravitropism is compromised due to which thigmotropism comes to occur.
There is a plant hormone called auxin, which guides most plants in their growth. It is found in Arabidopsis, too, yet the path that the hormone decides for the plant is very different than usual. They do not grow towards the gravity vector.
From the point of contact, which is everywhere under the ground at a molecular level, they tend to grow against gravity. These plants are also phototropic and often tend to glow in the dark.
That closes our list of plants that are sensitive to touch. This sensitivity is smart tactic that plants use to stay away from danger and acrquire food. Got a favorite touch-sensitive plant? Please do leave a comment.