The male Palmfarnzapfen heat up and drive with toxic substances the fringed wings of male to female plants. Photo: Irene Terry
Reading Palm Ferns use both attractants and aggressive substances to drive pollen-laden insects from male to female cones. This is how the plants ensure their reproduction. This is what Australian and American researchers found out when they studied the pollination of the cycads by fringed wingers. The insects settle on male cycads to eat the pollen they contain. When the cycad begins to heat its cones, the fringed flies flee and instead fly to female plants that release attractants that attract the insects. In the process, pollen sticking to the insect's body sticks to the cones of the female cycads. Up to once a year takes place at the Palmfarnen a pollination period. Then the male palm fern heats its cone daily for four weeks between eleven o'clock in the morning and three o'clock in the afternoon. Up to twelve degrees warmer it is here on the male Palmfarn than in the environment, explain the scientists. At the same time the plant emits a stinking and poisonous smell. This drives out the fringed wings that sit on the cone for eating.

In search of a new food source, the insects are attracted by the female cycads, which emit a fragrant fragrant fragrance. Although the insects do not find food here, they leave the pollen of the male cycads behind. In the late afternoon, then the male cone cools again and emanates an attractive scent for the fringed wing? The insects explain that the insects can load themselves with enough pollen until they are driven out of the plant by noon.

Palm ferns have been living on Earth for almost three hundred million years and are considered living fossils. Plants were probably the first to develop fragrances to fight off enemies. Later, species developed that attract insects to pollination with their scent, the scientists explain. The cycads are probably an intermediate stage of this development.

Irene Terry (University of Utah Salt Lake City) et al .: Science, Volume 318, page 70 ddp / science.de? Anja Baster's ad

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