Botany Blueprint: Burdock
Specimen #23: Burdock (Arctum minus)
What do NASA astronauts, new parents, and cardiac surgeons have in common? They all owe a debt of gratitude to the common weed burdock, whose hook-tipped burrs inspired the invention of Velcro. Hailed as the revolutionary “zipperless zipper,” the hook-and-loop fastener has been used to adhere disposable diapers, artificial hearts, and just about anything inside a weightless, orbiting space shuttle. Personally, if any adhesive were to evoke nostalgia, it would be Velcro, without which my hot-pink Reebok hightops and neon dolphin-themed Trapper Keeper (c. 1985), would not have been possible. The revolutionary fastener launched many a trend in fashion and product design, and it emulates a mechanism that was refined and perfected by a certain thistle: the burdock (Arctium minus in the United States, and (Arctium lappa mostly everywhere else). In the wild, the adhesive mechanism is designed for seed dispersal. Burdock is a plant that entangles itself in your affairs—and it hopes that your affairs are going somewhere.
As anyone who’s emerged from a forest with a burdock sleeve will agree, the wonderful story of Velcro’s genesis is too familiar to be apocryphal. In 1941, the Swiss engineer George de Mestral (1907–1990) encountered the plant while on a hunting trip in the Alps with his dog. Upon disentangling several burdock burrs from the dog’s fur, the engineer became curious about their design. He took a closer look under a microscope, which revealed the many tiny hooks that easily bind to most organic textures (fabric, fur, skin et al.). Ah ha! De Mestral saw great potential in this simple fastening device as an alternative to the zipper. While his notion of burdock biomimicry would eventually sweep through designs of the 1970s and 80s, it took a while to get right. He spent about ten years consulting with weavers and engineers, and experimenting with various fabrication methods. A patent for Velcro was granted in 1955.
Burdock burs attach themselves to unwitting passers-by, such as de Mestral’s dog, as a way to ferry the seeds into new territory. The tiny hooks are quick to latch onto anything, and they do not easily disengage. The seeds themselves are inside the barbed globe—about 40 to a bur, they drop to the ground when the vessel is pulled at. Burdock are thus different from other hitchiking plants, in which the barb is the seed itself—instead, the burdock’s seeds are loose and ready to propel towards new soil. It’s a mechanism I saw in action when I prepared to photograph a stem of burdock seed heads. My little spaniel bounded into the studio, tail waving as she tap-danced on the wood floor. Luckily, most of my specimens were higher than her, but not the burdock. With one sweep, her tail picked up the whole tangle of them. Agitated by uninvited travelers, her tail whipped faster, shaking the mature burs and launching hundreds of seeds across the room. Were it not for the walls and lack of soil, the burdock seeds would have been very pleased.
Today, according to Vecro enthusiasts, there is a call for de Mestral’s successor. While convenient and inexpensive, Velcro has one problem: It is famously noisy. Engineers are rumored to be toiling away at a silent revision. It should be noted that the plant itself does not go quietly—so, perhaps we should instead wait for burdock to evolve a silent mechanism? After all, its design seems hard to improve on.