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Some plants are real poisons. It is their way of defending themselves from predators, but they can also be useful to humans.
It has everything to please. And besides, he likes it. Lily of the valley, and its pretty white flowers in the shape of bells that we offer on May 1, nevertheless hides its game well. A single sprig of lily of the valley can send you to the morgue. It is estimated that 4% of the plants in the world are toxic, to varying degrees.
Some plants are even deadly, but it’s not for the fun of killing. ” A plant, if attacked, cannot save itself, unlike an animal.recalls the biologist Katia Astafieff, author of the book Bad seeds. A plant can neither fight nor hide since it is static. But some species have been able to develop, during evolution, defense mechanisms to avoid being eaten raw, by developing toxic molecules that will deter predators. »
winner winner
But in the face of toxic plants, all animals are not equal. Take the ivy, this species of creeper which produces berries in autumn. Everything in the plant is poisonous except to birds. ” Some animals are not sensitive to the toxicity of certain species, says Katia Astafieff. Birds will for example be able to transport the seeds of certain toxic species, which is interesting for the plant because it will allow its seeds to be disseminated, and it is interesting for the bird which will feed on them. »
Faced with a toxic plant, animals generally do not come back to it a second time. The human species, too, has learned to be wary of it. Then to use it, for example to make poisoned arrows or poison. In Athens, those sentenced to death, like the philosopher Socrates, had to drink hemlock, a potion, a poison, made from a plant, the spotted hemlock.
From death to life
But what kills can also heal us. “ Plants have a bit of a double life or play a double game, summarizes Katia Astafieff. The same plant can be both very toxic, even deadly, and at the same time the same molecule can be used to manufacture drugs. It is of course a question of dose. This is the case, for example, with the vomit nut, used as a stimulant, or the yew, a very toxic tree, from which a very important molecule has been extracted which is used to treat cancers.. Poisonous plants are often capable of the worst, and sometimes the best.
“We’re all going to die, and the birds too?” »
For the birds in any case, things are off to a bad start, according to the latest study, which refers, published this week by the NGO BirdLife. Half of the bird species in the world, 49%, are in decline – 4 years ago, we were “only” at 40%. One in eight species is directly threatened with extinction. In question, it will not surprise you, human activities, and in the first place intensive agriculture, which deprives birds of their habitat. The use of pesticides is also deadly, not necessarily for the birds directly, but for all the insects and plants on which they feed. Humanity, too, is toxic.