The Tibetan Plateau is a biodiversity hotspot, but for Primula chungensis at the side of the G318 National Highway, there's a problem.
A road verge can be a wildlife haven. They're mowed less, sprayed less, managed less. That offers a refuge for plants fleeing expanding farmland.
But Primula chungensis seemed to be suffering. Yong-Peng Cha and colleagues noticed that dust was settling over the flowers facing the road, and the seed pods looked different in flowers facing the road to the flowers facing away.
Here's the puzzle: Is the dust putting the bees off the flowers, reducing pollination, or are the flowers physically damaged by the dust, reducing their ability to send and receive pollen? It’s an easy question to ask, but harder to answer because the two explanations predict the same result. Fewer seeds near the road.
Fortunately the botanists had an answer. Some of these plants can self-pollinate. So they watched how bees reacted to dusty flowers, and how well dusty flowers self-pollinated.
When they watched bees they saw them spurning the dusty flowers. So the plants have a problem attracting pollinators. If that was the only reason, the self-pollinating plants should be fine.
But they found the self-pollinated plants also had reduced seed set. And it was worse the closer to the road you got. So dust settling on the anthers and stigmas of the flowers is harming self-pollination too. It means the plants are getting hit twice by the dust. Reduced attraction, and reduced success if they can attract a visit.
It's not just a problem for primroses. Cha and colleagues add that while the problem is worst at the roadside, it still reaches well beyond the road. That could become a problem for farmland.
Cross-posted to Bluesky and Mastodon.
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Cha, Y., Ma, Y., Inouye, D., Tong, Z., and Zhang, Z.(2026) Road air pollution harms the reproductive success of a bee‐pollinated wildflower: A dusty threat to biodiversity. PLANTS, PEOPLE, PLANET, 8(5), pp. 1567-1571. Available at: https://doi.org/10.1002/ppp3.70174.
