The long root of the burdock, Arctium minus, a biennial, is eaten as a vegetable in Asia, and its roots, leaves and seeds may have medicinal properties. The burdock grows small reddish-violet flowers on a pod covered with hooked spines. This bur, similar to a cocklebur, carries the seeds of the burdock.
The burr, or seed head, of burdock spreads by clinging to the fur or clothing of passing animals or people. When a burr breaks, it scatters rough dark gray to brown seeds about ¼ inch long. A burdock produces from 11,700 to 13,400 seeds per plant. These burrs ripen in the late summer of the second year of the plant's growth. The mature seeds can lie dormant for two years, although some of them germinate after 10 to 12 years of dormancy.
Collect mature, dried burrs in a bucket. Use gloves. You can thrash or beat the burrs to separate the seeds. If you have a large quantity of dried burrs, put them into a wood chipper. Run the chipper to free the seeds. Then winnow the seeds to remove the chaff.
Burdock seed does not do well in disturbed soil. It grows well in abandoned fields, undisturbed pastures, barnyards and along fences and roadsides. Sow seed about ¼ inch deep in the early spring into summer in partial shade to full sun. The seeds will germinate in one to two weeks in soil that is rich, sandy or clay. Water regularly. If you plant burdock seeds for their roots, space them 2 feet apart; if you are growing them for seed, plant them 4 feet apart. For long, slender roots, plant the seeds as close as 6 inches apart.
A University of Wisconsin posting on burdock by Julie Doll and Dr. Jerry Doll lists numerous uses of burdock as an alternative medicine based on anecdotal evidence. Tinctures and extracts of burdock seed are used to treat chronic skin diseases. Some Asians believe seed extracts are useful in treating kidney diseases, although its effectiveness for that purpose has not been proven in clinical trials. You'll even find references in medieval literature to Bardona, a concoction made of burdock seeds used to break up kidney stones.
Burrs and Velcro
In the early 1940s, George de Mestral, a Swiss inventor, took a walk with his dog. Along the way, burdock burrs collected on his clothes and on the fur of his dog. He later looked at the hook-and-loop spines of a bur under a microscope and was inspired to invent what we now call Velcro.