Orchids pollinate themselves using finger-like appendages

A type of orchid that eats fungi has an ingenious method of self-pollination. The secret lies in the orchid’s mysterious finger-like appendages.

“I thought there had to be something more than just something that looked strange,” says Kenji Suetsugu of Kobe University in Japan.

Mr. Suetsugu has been interested in this work for some time. Stigmatodactylus sikokianus This is because orchids live in the shady forests of Japan and feed on soil bacteria throughout their lives without relying on photosynthesis. Orchids also have a pinky-like appendage under the stigma, a sticky part that receives pollen during copulation.

To investigate the purpose of the appendages, the researchers observed flowers in the wild, set up pollination experiments in the lab, and tracked changes in the structure of orchids using fluorescence microscopy.

They noticed that if there are no insects visiting orchids for pollination, the flowers begin to wilt. As the finger-like appendages drooped, they gradually moved toward the stigma, bringing the pollen into contact with the sticky receptors.

The appendage thus acts “like a bridge,” transporting orchid pollen in a self-pollination trick, but only as a last resort, Suetsugu says. The wilting mechanism allows the plant to tolerate pollinators, but acts as a failsafe to ensure that the plant can reproduce even if the insects never arrive. The discovery “highlights how nature can come up with creative solutions to common problems,” Suetsugu said.

Katarina Nagar from the Australian Tropical Herbarium says the next step is to remove the appendage completely to see what difference it makes to the timing and efficiency of pollination.

This appears to be the first time such a self-pollination trick has been formally documented, although observations in the early 1990s suggested that two other closely related orchid species also use the unusual appendage for self-pollination. Mr. Nalgar points out that this suggests that.