Orchids are among the most successful flowering plants, with more than 22,000 species around the world. And that’s not just because of the obsession they inspire in their human fans.
Researchers spent 10 years studying orchids in South Africa, where the flowers are particularly diverse. The scientists say orchids became successful by changing or sharing pollinators, but staying loyal to fungi. Here’s one example. There are two species of orchids that live very close together in South Africa. One orchid deposits its pollen on a particular bee’s front legs. The other leaves pollen only on the bee’s abdomen. The same bee thus serves two different species and keeps the pollen separate.
But when it comes to fungi—which supply the orchid with nutrients—the flowers are much more faithful. They might switch pollinators if transplanted, but they stick with the same fungus species. And one orchid species uses different fungi than a close orchid neighbor, to prevent competing for the same nutrients. The research was published in The American Naturalist. [Richard Waterman et al., "The Effects of Above- And Belowground Mutualisms On Orchid Speciation and Coexistence"]
The scientists say the findings help explain how so many species of orchids developed, and can exist so close together. The human mania for orchids, however, remains mysterious.
—Cynthia Graber
