Marsh Marigold - Caltha palustris - Populage des marais

During my time at QUBS, I did some (undergraduate, short-term, for a field course) research on Caltha palustris (marsh marigold, fr: populage des marais), family Ranunculaceae. It was a remarkably profuse bloomer and appears to be a pollinator generalist - it was pollinated by just about any insect which pollinates flowers, including bees (mostly Apis mellifera), bumble bees (Bombus spp.), solitary bees (diverse groups from Hymenoptera), syrphid flies (Syrphidae), true flies (Diptera), beetles (Coleoptera), and ants* (Formicidae). There were also some moths & butterflies around (Lepidoptera) but following our observation paradigm, my colleague and I witnessed no instances of these pollinators visiting the flowers - most likely just because they were so rare that it would have taken considerably more observer effort to see the Lepidopterans visiting C. palustris. There was no indication that birds pollinate C. palustris and I have no idea if bats visit the flowers (unlikely, as flowers which are specialized to attract insects tend not to have the various specializations which would attract birds or bats).

C. palustris

Solitary bee on C. palustris

C. palustris' conservation status is unranked but considering that it grows in wetlands (an increasingly threatened ecosystem), one should presumably treat the plant with caution. It certainly appeared in remarkable profusion at our study site, so we did not take extraordinary measures to safeguard it against our movement through the marsh etc, but I cannot speak for other sites. A good rule of thumb is to damage as little as possible regardless of the conservation status of an organism.

C. plaustris came rapidly into bloom at the test site and the flowers began to senesce within a few days. It is unclear whether the floral senescence was triggered by pollination (pollinators were remarkably abundant) or if the plant only ever sustains them for a few days.

C. palustris at the marsh - day 0 (project planning)

C. palustris at the marsh - day 1 (data collection)

Our study looked at the impact of floral outline (highly variable in this species) on pollinator behaviour. Tentatively, our results suggest that  the introduction of A. mellifera may end up altering the phenotype distribution in this population, as the A. mellifera showed a statistically significant preference for floral morph where the native pollinators do not. This has widespread implications for plant populations in North America -- however, we should take these results with a huge grain of salt because the data was collected by two undergrads in three days and the stats were an overnight affair.

Research photo used to quantify floral outline variation

As above

As above

I actually enjoyed sloshing about in the marsh, even when I was wet and muddy and losing my rubber boots to the mucky depths.Somehow, the tedium of watching bees land on flowers all day in the muck was quite agreeable to me.

*it is possible that the ants were not pollinating but rather stealing nectar, ie taking the pollinator reward without providing any pollen transfer for the flower; ants do pollinate some flowers but are mostly nectar-robbers. My colleague and I did not have a chance to establish with any certainty whether the ants were antagonists or mutualists with C. palustris.

C. palustris