(ORDO NEWS) — Some flowers are able to drive away insects with the movements of the stamens. Experiments have shown that this saves nectar and makes room for the next guests, dramatically increasing pollination efficiency.
It has long been noticed that at the moment when an insect touches the nectar-producing glands in some flowers, their stamens bend sharply. The great Enlightenment naturalist Carl Linnaeus wrote about this.
New work by Chinese biologists has shown that this happens for a reason, allowing the plant to drive away insects in anticipation of the next and thereby contributing to successful pollination.
Plants are immobile, and many of them rely on animals, primarily insects, to transfer pollen from one flower to another.
To attract them, the flowers produce nutritious sugary nectar, sometimes in fairly large quantities. However, if one insect eats it completely, this will reduce the number of following visitors and reduce the efficiency of fertilization.
Therefore, plants are interested not only in attracting insects, but also in ensuring that each of them does not spend too much time on the flower.
This is helped by the “slaps” that the flowers apply with the help of their mobile stamens.
To demonstrate this, biologists conducted experiments with barberry and mahonia plants, both in the laboratory and in the field.
They immobilized the stamens by immersing the flower stems in alcohol for 35-45 minutes. First, the scientists made sure that such a procedure does not affect the attractiveness of flowers to pollinators, and then compared the behavior of insects on them, as well as on ordinary flowers.
In addition, they stained the pollen to track the efficiency of its transfer to other plants.
The procedure did not affect the species composition of pollinators. However, the insects spent 3.6 times more time on flowers with immobilized stamens than usual and consumed noticeably more nectar.
At the same time, they carried half as much pollen as for flowers with normal mobile stamens. Moreover, pollen from them was found on three times less number of other plants, and the distance to them was less than that of pollen from flowers, which retained the ability to drive away insects with the “slaps” of their stamens.
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