What’s the best way to attract pollinators, if you’re a plant? Should you aim for a specialist partner, who has a close connection to your flowers, or should you be a generalist and attract many pollinators, so you’re not in trouble if your favoured pollinator disappears? Moricandia arvensis, the Purple Mistress of the Mediterranean has it both ways, producing a different flower for spring and summer.
Spring is all about impact, with large, purple, cross-shaped flowers. These attract specialised long-tongue bees. Yet when the summer comes, things change dramatically. The flowers are small and white and welcome a wide variety of insects. The change isn’t simply cosmetic. Spring flowers produce three times more nectar than their summer versions. It’s like the flower is plant from being an elite club to an open house.
Gómez and colleagues wanted to know how this strategy and the pollinators it attracted affected Moricandia arvensis’s reproductive success. They observed flower visitors at six different sites in Spain over an eight year period. This meant recording over 6700 visits to the plants.
They also tracked the effectiveness of the pollinators. Over eight hundred virgin flowers were exposed to insects belonging to 13 pollinator functional groups. Once the flower was visited, Gómez and colleagues ripped off the petals, to prevent further visits, marked who had visited the flower, and came back to see how effective the seed set was.
The spring flowers had a clear champion, long-tongued bees produced over three quarters of the seeds, and a further 11% came from beeflies. But the results from summer flowers were much more mixed, short-tongued small bees led with 26% of seed production, followed by long-tongued large bees at 19%, and extra-small bees at 17%. Surprisingly, some frequent visitors, like flies and beetles, proved to be rubbish at pollination.
Gómez and colleagues show plants can adapt to changing conditions by completely reinventing their pollination strategy between seasons. What makes Moricandia arvensis particularly special is that it’s successful at being a generalist in two different ways. In spring, it effectively uses several types of long-tongued insects, while in summer it benefits from an even wider range of pollinators. Rather than compromising between specialisation and generalisation, Moricandia arvensis takes an approach where it can be a successful generalist in both seasons, while still taking advantage of differences in pollinator quality to maximize its reproductive success.
Gómez, J.M., González-Megías, A., Armas, C., Narbona, E., Navarro, L., Perfectti, F. & Caravantes, A. 2025. Pollination effectiveness affects the level of generalisation of a plant species with phenotypically plastic flowers. AoB Plants. https://doi.org/10.1093/aobpla/plae065
Cross-posted to Bluesky & Mastodon.
Cover image Moricandia arvensis in the spring. Photo: Joanbanjo / Wikimedia Commons, CC BY-SA 4.0
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