Plants of the genus Arctium have dark green leaves that can grow up to 18" (45 cm) long. They are generally large, coarse and ovate, with the lower ones being heart-shaped. They are woolly underneath. The leafstalks are generally hollow. Arctium species generally flower from July through to October.
The prickly heads of these plants are noted for easily catching on to fur and clothing, thus providing an excellent mechanism for seed dispersal. Burrs cause local irritation and can possibly cause intestinal hairballs in pets. However, most animals avoid ingesting these plants.
A large number of species have been placed in genus Arctium at one time or another, but most of them are now classified in the related genus Cousinia. The precise limits between Arctium and Cousinia are hard to define; there is an exact correlation between their molecular phylogeny. The burdocks are sometimes confused with the cockleburs (genus Xanthium) and rhubarb (genus Rheum).
The roots of burdock, among other plants, are eaten by the larva of the Ghost Moth (Hepialus humuli). The plant is used as a food plant by other Lepidoptera including Brown-tail, Coleophora paripennella, Coleophora peribenanderi, The Gothic, Lime-speck Pug and Scalloped Hazel.
Italian Americans are known to use the peeled stems of the burdock. Referred to as "cardune", these stems are prepared in a battered frittata, a common dish on a St. Joseph's Day Table.
Burdock is a traditional medicinal herb that is used for many ailments. Burdock root oil extract, also called Bur oil, 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. Modern studies indicate that Burdock root oil extract is rich in phytosterols and essential fatty acids (including rare long-chain EFAs), the nutrients required to maintain a healthy scalp and promote natural hair growth. It combines an immediate relieving effect with nutritional support of normal functions of sebaceous glands and hair follicles.
According to some European herbalists, combining Burdock root oil with a Nettle root oil and massaging these two oils into the scalp every day has a greater effect than Bur oil alone.
Burdock has been used for centuries as a blood purifier clearing the bloodstream of some toxins, and as a diuretic (helping rid the body of excess water by increasing urine output), and as a topical remedy for skin problems such as acne, eczema, rosacea and psoriasis.
After taking his dog for a walk one day in the early 1940s, George de Mestral, a Swiss inventor, became curious about the seeds of the burdock plant that had attached themselves to his clothes and to the dog's fur. Under a microscope, he looked closely at the hook-and-loop system that the seeds use to hitchhike on passing animals aiding seed dispersal, and he realised that the same approach could be used to join other things together. The result was Velcro.
The Russian writer Leo Tolstoy wrote in his journal, in 1896, about a tiny shoot of burdock he saw in a ploughed field, “black from dust but still alive and red in the center … It makes me want to write. It asserts life to the end, and alone in the midst of the whole field, somehow or other had asserted it.”
Because the roots of burdock closely resemble those of Deadly nightshade (also known as belladonna or Atropa belladonna), there is a risk that burdock preparations may be contaminated with these potentially dangerous herbs. Be sure to buy products from established companies with good reputations. Do not gather burdock in the wild unless you know what you are doing.