Known as Wild teasel, I’ve found three of these plants growing along the river Clyde walkway in Glasgow. It’s hard to miss due to the large size and the peculiar inflorescence, although I believed they flowered in rings around the central axis of the head, but the photo I took shows something quite different!
Its appearance is not the only interesting feature though, as what can happen within the ‘cups’ formed by the opposite sessile leaves is far more interesting, at least in my opinion.
A study conducted in London in 2010 has provided evidence that this plant benefits from the invertebrates which die and decompose in the above mentioned cups. This basically means that it is partially carnivorous, or protocarnivorous, as it doesn’t produce its own digestive enzymes. Although it might be a bit surprising, hundreds of plants that we wouldn’t suspect actually show the same characteristics of partial carnivory, and I find it so interesting, maybe because it looks like there’s still a lot to learn about these mechanisms.
D. fullonum Sativus, a cultivar of the wild teasel, has also been historically important and widely used in the processing of wool, as the name suggests. This is reflected in the Italian name of the plant, Cardo dei lanaioli, which translates as ‘Woolman’s thistle’, although it isn’t a true thistle like the species within the Asteraceae.
This year the same colony is much bigger, both in number and in the size of its numerous individuals so I could take photos of the cups, the primitive pitfalls formed by the leaves on mature plants. They were the size of cereal bowls and who knows if the mush at the bottom was part-invertebrate!
Closing the circle with this biennial species I followed closely for its two years of life. The persistent seed heads of the dead plants keep rocking in the wind, while the seeds have already been overwintering at their feet, ready to start another cycle. I collected some last year when they were ready, and will do again if I’m around when the next generation is mature enough.
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