Yesterday Karin and I took to our bikes and rode south through some very nice, managed beech and oak woodland that runs parallel to the Isefjorden in this part of Odsherred. In was cold but sunny, birds were singing, and we saw the occasional insect on the wing. The kind of day that reminds you that spring is coming fast. On the way back we paused at a small housing development near the former psychiatric hospital at Annebergparken. In an area of disturbed ground I was delighted to see a patch of coltsfoot (Tussilago farfara) in full flower, the dandelion-like inflorescences a beacon to passing bees and flies.
Although it resembles a small dandelion, and belongs to the same family (Asteraceae), Tussilago is only distantly related to Taraxacum. Coltsfoot is really a type of groundsel (tribe Senecioneae) whereas dandelions are related to chicory (tribe Cichorieae).
Coltsfoot is unusual in that it produces its flowering stems long before the leaves that give it its common name, the plant’s reproduction powered by the energy that it stored up the previous year. Dandelions, like most herbaceous plants, produce their leaves first, then flower. That’s not the only difference to dandelions though.
The Database of Pollinator Interactions (DoPI) lists 9 species of insect that have been recorded as visiting coltsfoot for nectar and/or pollen. In contrast, the entry for Taraxacum officinale lists more than130 species as flower visitors. I thought initially that it might be due simply to under-recording, but this study of coltsfoot in Germany only recorded 16 insect species. So the greater attractiveness of dandelion is likely to be real. Why the big difference in pollinators?
One reason for it could be that dandelions have a very different flowering strategy; they can be in flower 12 months of the year, depending on local weather conditions, with a reproductive peak in May or June. They therefore have the opportunity to interact with many more insects than coltsfoot, which in contrast you generally only see in flower between March and May at the very latest.
Dandelions are also much more abundant than coltsfoot which is no doubt also a big factor in determining how often insects are observed on the flower heads. It’s not unusual to see whole fields full of dandelions in flower but I’ve never seen coltsfoot do that, perhaps because they prefer to grow on rather disturbed ground.
There may be some other factors at play here that I’m not aware of, for example a lower rate of nectar production in coltsfoot. Having said that, the fact that dandelions produce any nectar at all is a real conundrum. All of the literature claims that Taraxacum officinale is “apomictic“, a plant reproductive strategy in which seeds are produced without requiring ovules to be fertilised by pollen. In fact the online Ecological Flora of Britain and Ireland entry for dandelions lists the pollen vector as “none” for that very reason. But I’m sure that the real story is more complicated, otherwise why would these plants invest so much of their energy and resources in attracting and rewarding flower visitors? I’ve not delved deeply into the Taraxacum literature so perhaps one of my readers knows?
Our encounter with coltsfoot reminded me of the work that I did last year with the Stanwick Lakes nature reserve in Northamptonshire, advising on how best to enhance and manage the site (which is primarily a bird reserve) for pollinators. One of my recommendations was that they enlist their volunteers to collect seeds and root or stem cuttings from the small, isolated populations of early-flowering plants such as coltsfoot (pictured on the reserve below) and introduce them around the site in suitable spots. This would both increase the availability of nectar and pollen for the first flower visitors of spring, and also the ecological connectivity between different parts of the site as the pollinators are able to move around more effectively. So I was delighted to see this post on LinkedIn from Liz Williams who works at Stanwick, demonstrating that they have taken my advice on board and begun the hard work of planting for pollinators.
My work with Stanwick was an example of the advisory and consulting services that I offer. If you’d like some advice on how to improve an area for pollinators, or for biodiversity more broadly, please do get in touch via my Contact page.