An orchid uses finger-like appendages to pollinate itself

A species of fungus-eating orchid has a simple self-pollination method. The secret lies in the orchid’s mysterious finger-like appendage.

“I knew there had to be more to it than just a weird-looking quirk,” says Kenji Suetsugu At Kobe University in Japan.

Suetsugu had long been attracted to Stigmatodactylus sicocianus Orchid because it lives in shady Japanese forests and feeds on soil fungi throughout its life rather than relying on photosynthesis. Orchids also have a small finger-like appendage beneath the stigma, the sticky part that receives pollen during copulation.

To investigate the purpose of the appendage, the researchers observed the flower in the wild, set up pollination experiments in the laboratory, and tracked changes in the structure of the orchid flower with fluorescence microscopy.

He observed that if no insect came to pollinate the orchid, the flower began to wither. As it bent, the finger-like appendage slowly moved towards the stigma, bringing the pollen into contact with the sticky receptor.

The appendage thus acts “like a bridge,” says Suetsugu, transferring the orchid’s pollen in a self-pollinated move, but only as a last resort. The mechanism of wilting allows the plant to remain ready for a pollinator, but acts as a fail-safe, ensuring that it can reproduce even if an insect never arrives. “This discovery highlights how nature can bring truly creative solutions to common problems,” says Suetsugu.

The next step would be to remove the appendage entirely to see how much of a difference that makes to pollination time and efficiency, he says. Katharina Nargar In the Australian Tropical Herbarium.

Although this appears to be the first time that such a self-pollination device has been formally documented, Narger says observations from the early 1990s suggest that two other closely related orchid species They also use their unusual appendages for self-pollination.