Hooking a free ride

Burdock

Although technically a year-round plant, burdock is one that you usually notice most in the fall and winter. That’s because it’s at this time of year that the seed heads dry out and hook themselves on just about any passer-by who unwittingly gets too close. They particularly like socks and shoelaces. And horses’ tails, and long-haired dogs. Golden Retrievers are their favourites.

Burr

The challenge of dispersing seeds is something every plant has had to evolve a solution to. Many will cast their seeds out to the wind by producing lightweight seeds, or creating a “parachute” to carry a heavy seed (like milkweed puffs or maple keys). Some put their seeds in a fruit and encourage animals to carry them away to a new location. In this case, the burdock has developed long spines with hooks on the end that protrude from the seed case. The hooks snag loose hairs and the dry burr head pulls off the stem, catching a free ride. The hooks are so strong and effective that they’ve been recorded to snag and trap tiny birds.

Burr hooks

Check out those hooks close up. They look like miniature fish hooks! In fact, they’re the inspiration behind the widespread everyday material, Velcro. Velcro was the brainchild of Swiss inventor George de Mestral, who came up with the idea after taking his dog for a walk and observing the seed heads that they both came home with (I bet he owned a Golden Retriever). He examined the hooks under his microscope when he got home, and wondered if a similar hook-and-loop system could be used as a fastener. Velcro was born in 1945 and patented in 1955; today it’s a multi-million dollar company.

Interestingly, despite being incredibly common, burdock isn’t native to North America. Originally from the “Old World”, it has been introduced to this and many other continents. In Asia, the taproot of the plant is commonly eaten as a tuber, the way we eat carrots. In the UK, there’s a soft drink called “Dandelion and Burdock” (I’d be interested to taste that one!). Burdock root oil extract has also been used in herbal medicine to cure scalp conditions like dandruff and increase hair vitality. Pretty cool for a plant that the only consideration many of us give it is cursing under our breath while plucking it from our socks.

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4 responses to “Hooking a free ride

  1. Another thing about burdock that kids may know: the insides make a wicked itching powder!

  2. themarvelousinnature

    I didn’t know that! Wish I had back when I was a kid. Thanks for sharing!

  3. christine kohlert

    Hello I’m writing a book on Spaces for Creative Thinking. I’m desperatly looking for a picture of a bur under a microscope, as Mistral saw it! I really need help!!! I hope anyone answers!! thanks so much: cko@rbs1.com

  4. christine kohlert

    no one to answer me??? I need that picture about the burr SOOO URGENTLY !!! in high res

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