Take Turns: A Survival Strategy

Alpine plants in a region of Tibet have survived and diversified over millennia through a kind of floral courtesy.

Butterfly on a flower in the Hengduan Mountains: By flowering at different times, plants don't compete for pollinators. Photo: Columbia Department of Evolution and Environmental Biology

You learned it in nursery school or, among siblings, even earlier. Nobody has to die over the Etch-a-Sketch because everybody will get to scribble. Just wait your turn.

Flowering rhododendron, one of scores of varieties in the Hengduan Mountains.
Photo: Qui Li

A team of botanists studying the astounding floral diversity in the Hengduan Mountains of China discovered a similar strategy among plants. Scientists had wondered how the dozens of varieties of rhododendron and other flowers that thrive in this region had managed to survive instead of competing to the death.

Rich Ree of Chicago’s Field Museum, one of the research leaders, spelled out the severe truth: “If two species with the same lifestyle are living in the same space, they’ll compete will each another so that either one or both of them will adapt to have different, non-overlapping lifestyles or they’ll go extinct.”

(…which explains why country clubs are so unpleasant.)

Ree proposed several ways plants might evolve to share the environment: “they can become very different in terms of their preferences for soil, light, and moisture.” They also can evolve flowers of different sizes, shapes and colors to attract different pollinators and thus avoid cross-breeding.

Many of these factors have likely been at work to produce such variety in the Hengduan Mountains. Furthermore, scholars of biodiversity have determined that the plants here have “been evolving for longer than alpine flora found anywhere else on Earth.” They’ve had a long time to learn “live and let live.”

A butterfly pollinates a flower in the Hengduan Mountains
Photo: Columbia Department of Evolution and Environmental Biology

In their 2022 report published in the Journal of Ecology, Ree’s team makes the case that the diversity of rhododendron plants here is very likely due to turn taking. He said botanists had observed that the bloom season of rhododendrons here is conspicuously long. “There are some species that put out striking blossoms against a backdrop of a field of snow and others that wait until the end of the summer.” But it took meticulous tracking by researcher Qin Li, who checked 100 sites repeatedly during the whole bloom season, to confirm the pattern and distinctiveness of flowering-phases.

“By partitioning that timeline,” Ree explains, “they can reduce their chances of wasting their pollen and the resources that go into reproduction.”

By taking turns at flowering, the plants aren’t competing for pollinators; each species is better able to survive and avoid cross-pollination – maintaining its integrity.

Until today we knew nothing about this mountainous region on the Tibetan plateau. Yet it seems diversity extends also to its human inhabitants.

The Hengduan Mountains extend north/south on the Tibetan Plateau.
Map: Wikipedia

“Home to a mosaic of ethnic groups—including Tibetan, Qiang, Yi, Naxi, Lisu and many others—the region preserves a wealth of languages, customs and crafts. Villages cling to terraces along steep slopes, where dairy farming, weaving, wood carving and traditional medicine continue to thrive alongside modern livelihoods.”

Perhaps the day will come when science can confirm “seasonal” differences among ethnicities too. We aren’t familiar with the Qiang, Yi, or Naxi people, but we have detected special florescences among Celts in the spring, Zapotecs in November, and Germanic people in late December.

There may be cultural “turn-taking” in these ancient mountains also that has permitted its human residents to maintain their distinctions rather than dissolving into a melting pot or, in the warfare we call “competition,” driving one other to extinction.

Note: Don’t miss plantsman Allen Bush’s 2011 story of a collecting trip to Sichuan. He was there September 11, 2001 when the Twin Towers fell.