Orchids are among the most devious flowering plants on the planet. Many species trick pollinators into helping them reproduce. Some release sex pheromones that attract male insects, whereas others make fake pollen to tempt bees and other pollinators with the promise of a meal. Scientists have now shown this pseudopollen isn’t just an alluring counterfeit: It’s as nutritious as the real thing.
The work is “a step forward” for the field says Kevin Davies, a botanist and specialist in orchid anatomy at Cardiff University who was not involved with the research. This is the first time scientists have been able to show pseudopollen isn’t just fool’s gold, he says.
Like most orchids, Cypripedium wardii doesn’t produce edible pollen. The species—native to China and Tibet and characterized by slipper-shaped peppermint blossoms—must use other means to entice its insect pollinators. Its flowers don’t offer nectar, nor do they seem to have an appealing fragrance. Instead, their lips are dusted with a powder formed by small hairs that break off, coating the surface; it looks a lot like actual pollen.
Several types of orchid produce this pseudopollen. Some contains lipids, carbohydrates, and proteins. Others contain no nutrients at all. Though the substance was first described more than 100 years ago, scientists didn’t know whether insects actually ate it.
In the new study, researchers at the Chinese Academy of Sciences observed 12 species of solitary bee and hoverfly, harmless relatives of the pests that swarm our garbage, collecting pseudopollen from C. wardii orchids in the forested mountains of Sichuan province. The scientists caught some of the insects and brought them back to their lab for dissection. Slicing into the tiny corpses, they discovered particles of pseudopollen moving through their digestive tracts, as they reported last month on the preprint server bioRxiv. Analysis of the particles found that they contained lipids, indicating their nutritional value.
“This is the first time we have confirmed that pseudopollen is a real reward,” says co-author Luo Yi-Bo.
But are the insects really being tricked? Rodrigo Singer, a botanist who studies orchid pollination at the Federal University of Rio Grande do Sul doesn’t think so. He believes the bees and hoverflies sense that the pseudopollen is nutritious—so the orchids aren’t pulling a fast one on them.
Either way, Davies hopes the findings will encourage scientists to look at the pseudopollen produced by other orchids to see whether it, too, might be eaten. Regardless of whether they deceive their guests, C. wardii orchids seem to have evolved a clever way to ensure that their flowers get fertilized.