Many people mistakenly call burdock (Arctium minus) wild rhubarb because the large leaves look very similar to true rhubarb in size and arrangement. If you’re wondering which of these you have, look at the leaf undersides and stems; if they have tiny, soft, whitish hairs, the plant is likely burdock. There is no wild rhubarb in Minnesota.
Burdock is a widely distributed Eurasian weed with large leaves and a stout taproot that can be found across the continental United States. Locally, it’s found in unmaintained open areas, woods, pastures and feedlots. It spreads only by seed.
Burdock is a biennial that completes its full life cycle in two growing seasons, producing a rosette of very large leaves the first year—the stage that looks like rhubarb—and a tall branched stem with flowers the second year. The second-year stem can grow up to six feet tall and have many alternating branches. Stem leaves are egg-shaped and become smaller toward the top of the stalk. The flowers occur mid-summer in clusters at the top and in the leaf axils of second-year plants. They look much like thistle flowers with lavender, thread-like petals.
The short-lived flower sits on top of a half-inch-diameter ball-shaped green bur that turns brown in early autumn. With their small hooked barbs, burs easily cling to clothing, shoes, and animal fur. Each bur contains about 40 seeds. Once the seed has ripened, the whole plant turns brown and dies. Inside the burrs of the dead plant are viable seed.
Understanding this plant’s life cycle allows easy control without herbicide during two stages of the plant’s life. Seedling plants can be easily dug when the tap root is small. Once the plants are larger, digging is very difficult, since taproots can grow one to two feet deep. If the tap root is cut with a shovel, the plant grows back similar to a dandelion.
At the end of the plant’s life cycle, the brown burs containing seeds can be cut off of the dead plant and bagged or burned. Since it is likely that many weed seeds remain in the soil, these two techniques will likely need to be done annually until the seed bank in the soil is exhausted.
More fun facts about burdock
- The barbs on the burs of burdock were the inspiration for Velcro, invented in the early 1940s by Swiss inventor George De Mestral.
- The taproots of young burdock plants are eaten in Asia, particularly in Japan where Arctium lappa (greater burdock) is harvested and eaten as a root vegetable. Burdock root is crisp, sweet and mild, with a pungent flavor.
- Burdock is a traditional medicinal herb that is used for many ailments, and generally referred to as a “blood purifier.” Though the roots of the plant are most commonly used for medicinal purposes, all parts of the plant have their recommended uses. Burdock root oil extract is popular in Europe as a scalp treatment applied to improve hair strength, shine and body, help reverse scalp conditions such as dandruff, and combat hair loss.
- Though burdock is not widely used relative to many other botanicals, it is still employed by some herbalists as a diuretic, as a laxative, for rheumatic complaints, to treat gout, and to relieve various skin problems including eczema, psoriasis, boils and sores. Burdock is typically consumed as a tea.