In the middle of summer, under a scorching sun, humans sweat, animals seek shade... but plants can't move. Yet they often manage to survive despite extreme temperatures. How do they do it?
Illustration image Unsplash Plant transpiration
Like us, plants "sweat" — but in their own way. They release water through tiny pores on their leaves called stomata. This evaporating water helps cool them down, somewhat like our sweat.
But this strategy has its limits. If the plant loses too much water, it risks drying out. It then closes its stomata to limit losses, but this also blocks photosynthesis, which requires CO₂ to function. It's a delicate balance.
Adapted leaves
Some plants have developed highly specialized leaves: small, thick, covered in hairs, or even needle-shaped (like pines). These shapes reduce the surface area exposed to sunlight and limit water loss. Others have a shiny or waxy surface to reflect some of the light.
Succulent plants like cacti or aloe vera are champions of survival in dry environments. They store water in their leaves, stems or roots, like an internal water bottle. They grow slowly but can last a very long time without rain.
Illustration image Unsplash A clever root system
Some plants send their roots very deep into the soil to find moisture where it remains. Others, on the contrary, have very widespread roots just below the surface to quickly capture the slightest drop of rain.
Sometimes the heat is too intense and the plant goes into "pause" mode: it slows its activity, stops growing and waits for better conditions. Some shed their leaves, others curl up. This forced rest allows them to conserve their resources.