An orchid uses a finger-like appendage to pollinate itself

A species of orchid that eats fungi has an ingenious method of self-pollination. The secret lies in the orchid’s mysterious finger-shaped appendage.

“I knew it had to be more than just a weird look,” he says Kenji Suetsugu at Kobe University in Japan.

Suetsugu had been in awe of it for a long time Stigmatodactylus sikocianus orchid, because it lives in shady Japanese forests and feeds all its life on fungi in the soil, instead of relying on photosynthesis. Orchids also have a little finger-like appendage under the stigma, a sticky part that collects pollen during mating.

To investigate the purpose of attachment, Suetsugu observed the flower in the wild, set up pollination experiments in the laboratory, and followed the changes in the orchid’s flower structure with a fluorescence microscope.

He noticed that if the orchid was not visited by pollinating insects, the flower began to wither. As it descended, the finger-like appendage gradually moved toward the stigma, making contact with the sticky pollen receptor.

The appendix thus acts “like a bridge,” says Suetsugu, transferring the orchid’s pollen in a self-pollination trick, but only as a last resort. The wilting mechanism allows a plant to retain a pollinator, but also acts as a safety net, ensuring that it can reproduce even if an insect never arrives. The discovery “highlights how nature can provide really creative solutions to common problems,” says Suetsugu.

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

While this appears to be the first time a self-pollination trick has been formally documented, Nargar notes that observations from the early 1990s suggest that two other closely related orchid species also use their unusual appendages to self-pollinate.