Soundcloud

A cloud of sound. Can you imagine?
"AAAAAAAAAAAASHARLFGKSDSDJFGKSFGJKGHFGLARBSDFGLUIGETHJYJK"

Plants may not have complex tissues and a nervous system, but they still "feel". If they sprout, develop and flower at the right time and place, that's because they are sensitive to environmental factors. The vegetation boom during each spring shows they obey precise rhythms, which come encoded in their genes. Plants do not have only a touch sensitivity (that has been known for quite some time), but also a chemical one, not to mention their sensitivity to light and temperature variations.

This way, plants can appreciate the length of the day and the air temperature, adopting a position fitting their neighborhood. A wound, stress or a disease trigger specific defense mechanisms. Information about their state and environment circulates along signals transmitted from one cell to another, from plant to plant, or even from one plant to other beings. Their sensitivity translates via movements, growth directions and metabolism changes.

Plant touch

Any plant reacts to the slightest touch. In the case of about 1,000 species, this reaction is almost instant: carnivorous plants close their trap immediately, the sensitive plants (like Mimosa) retreat their leaves, while nettles break their stinging hairs. In all the other 240,000 species, movements are slower. At the slightest touch, the plant Sparrmannia africana opens up its staminas, making crossed pollination possible.

Some plants from the family of the cucumber reduce the length of their stem, increase their diameter and turn stiffer in the next 48 hours after experiencing a rub. Trees exposed repeatedly to the attacks of winds and rains react in the same way, thus creating asymmetry.

Legumes have a specific swelling called pulvinus at the base of their leaves. This organ triggers rapid movements (of less than a second), as a reaction to touch or light variations. A sensitive plant requires 30 minutes to return to its initial position, especially if it has been stimulated repeatedly. Darkness causes the folding of the leaves and flowers (in the case of clover and other species) or their opening (in the case of the nightshade).

When in danger, plants also emit SOS signals. The phenomenon was first signaled in the bean attacked by mites. The plant emits an array of chemicals that attract other mites, predators of the first. The presence of the Spodoptera caterpillars on the corn leaves triggers the release of a chemical cocktail that attracts the parasitoid wasps of these larvae. Just one molecule from the saliva of the caterpillar is enough to cause the SOS signal. The tobacco chemically attracts the wasp Cardiochilles nigriceps, when attacked by the caterpillars of the moth Heliothis virescens, but it remains inert to the presence of the caterpillars of Helicoverpa zea (that attacks the corn).

Some corn varieties defend themselves against the root worm (Diabrotica virgifera), emitting chemicals that attract minute nematode worms that kill the root worms, which are in fact the larvae of a beetle.