Ethnobotanical Asteraceae: the versatile burdock

It was impressive to see the students on the rain-drenched field trip the other day retaining their sense of humour. One amused himself by giving another's hat a pom-pom style decoration using a burr - the flower head of a burdock. Burdock, as Asteraceae collectors may know, is Arctium minus, the lesser or common burdock.

CC image by Mike Pennington

If you're feeling childish you can throw these flower heads from some distance and they'll stick firmly and annoyingly on people's clothing. If you look closely at the spiny bracts you'll see why they stick so tenaciously:

CC image by El Grafo

One day in 1941, George De Mistral was walking his dog in the Swiss Alps (this was not unusual, he was Swiss) when his dog ran through some burdock and picked up lots of the burrs. Doubtless he may have sworn at the need to pick them all out from its fur, but being an engineer his brain started ticking. And the result of this encounter was the marvellous invention of Velcro. I'm sure you must own at least one thing that uses it. I hear it even comes in very handy on the space station, where it stops things floating around. Apparently the 'vel' part is for the 'velour' of the woolly side, and 'cro' for the hooks, like crochet.

Many seeds have evolved to be spiny and spikey, to catch onto passing animals and enable them to get dispersed much more widely than if they just fell off a plant. But burdock is slightly more cunnning than this because the seed is at the other end from the hook, and so the seed doesn't get inextricably tangled up - it can easily break free and drop to the ground when the hooked-on burr gets brushed about. I think that's the theory. I am going to find a burdock and test this out, as I might be confused. You can read a Serious Scientific Paper about burdocks and their hooks here if you're interested.

So if you're collecting Asteraceae, it's very much worth looking at the seeds and the seed heads - many are still around although it's getting decidedly wintery. In fact the stickiness of the burdock heads doesn't truly come into its own until they are very brown and dead-looking, because it's only then that they can fall apart and disperse the seeds.

CC image by the Neuchatel Herbarium

You can stick them down separately on your herbarium sheet, and perhaps draw a magnified version in your notebook. The whole seedhead might squash down nicely with lengthy pressing, as you can see from this sheet from the Neuchatel Herbarium Project.

Another interesting thing (to me at least, I have a number of strange interests it's true) is that the burrs of Lesser burdock feature in one of those strange British seasonal customs. You know, the sort of thing that wouldn't look out of place in The Wicker Man. Something with a large dose of eccentricity and more than a hint of paganism. Something completely incomprehensible to outsiders (and possibly to those taking part in it as well, but who cares). When we've got the Burry Man why do we need to Brexit?

The Burry Man. CC image by Oliver Benton

You can just see the Forth Bridge in the background - the ceremony takes place in South Queensferry in Scotland. I was reading a Victorian newspaper article describing it from the 1840s, and it was ostensibly to encourage the local fish shoals to reappear. The requirements include lots of burrs (11,000 according to Wikipedia) and two staves with flowers (as you can see).

Another Lesser burdock cultural connection is that strange-tasting concoction, Dandelion and Burdock. It's made from the plants' roots. Herbalists claim all sorts of things for it but I don't know if they've been scientifically substantiated. If it's not particularly good for you I can think of other things you might prefer the taste of. It's another eccentric British classic.

CC image by Diadoco