Beautiful butterworts

A recent hike in Königssee to see Germany’s highest waterfall was a little underwhelming but the hydrological shortcomings were entirely forgotten when I spotted this beauty growing in a crevice above the lake:

Butterworts are amongst my favourite carnivorous plants: their murderous ways are so delicately concealed. Who would suspect such a pretty bank of flowers to be a veritable morgue of fungus gnats?

I’ve seen wild butterworts once before (in the Slovenian Alps), where they were obligingly in flower, as you can see above. The two commonest species in the Alps are the white-flowered Pinguicula alpina (alpine butterwort) and the purple-flowered Pinguicula vulgaris (common butterwort): the latter is also found in the UK, but is by no means ‘common’ here. The photo at the top could be either of them, but without the giveaway flowers it’s difficult to tell which.

Like many carnivorous plants using the’ flypaper’ trapping mechanism, butterworts hold their flowers at some distance from their leaves: the usual explanation for this is that it helps the plant to avoid accidentally capturing its pollinators, but I can find no proper data that support this. The butterworts’ pollinators are evidently fairly large: probably butterflies with long tongues, judging by the very long nectar tube, which you can see in the image of one of the other native UK species (Pinguicula grandiflora) below:

Butterflies don’t strike me as likely to end up as accidental prey, considering the usual prey is extremely small (about 1 mm) flies:

It’d be pretty easy to design an experiment to investigate this properly, perhaps with the cape sundew Drosera capensis or Alice sundew  Drosera aliciae which are not closely related, but which use a similar trapping mechanism. If you’d be interested, let me know!