Plants of the genus Arctium have dark green leaves that can grow up to 28" (71 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 (burrs) are noted for easily catching on to fur and clothing (being the inspiration for Velcro), 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.
Birds are especially prone to becoming entangled with their feathers in the burrs leading to a slow death, as they are unable to free themselves.
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.
Food and drink
The taproot of young burdock plants can be harvested and eaten as a root vegetable. While generally out of favour in modern European cuisine, it remains popular in Asia. In Japan, Arctium lappa is called "gobō" (牛蒡 or ごぼう); in Korea burdock root is called "u-eong" (우엉) and sold as "tong u-eong" (통우엉), or "whole burdock". Plants are cultivated for their slender roots, which can grow about one metre long and two centimetres across. Burdock root is very crisp and has a sweet, mild, and pungent flavour with a little muddy harshness that can be reduced by soaking julienned or shredded roots in water for five to ten minutes.
Immature flower stalks may also be harvested in late spring, before flowers appear; their taste resembles that of artichoke, to which the burdock is related. The stalks are thoroughly peeled, and either eaten raw, or boiled in salt water. Leaves are also eaten in spring in Japan when a plant is young and leaves are soft. Some A. lappa cultivars are specialized for this purpose. A popular Japanese dish is kinpira gobō (金平牛蒡), julienned or shredded burdock root and carrot, braised with soy sauce, sugar, mirin and/or sake, and sesame oil. Another is burdock makizushi (sushi filled with pickled burdock root; the burdock root is often artificially coloured orange to resemble a carrot).
In the second half of the 20th century, burdock achieved international recognition for its culinary use due to the increasing popularity of the macrobiotic diet, which advocates its consumption. It contains a fair amount of dietary fiber (GDF, 6g per 100g), calcium, potassium, amino acids, and is low in calories. It contains a polyphenol oxidase, which causes its darkened surface and muddy harshness by forming tannin-iron complexes. Burdock root's harshness harmonizes well with pork in miso soup (tonjiru) and with Japanese-style pilaf (takikomi gohan).
Dandelion and burdock is today a soft drink that has long been popular in the United Kingdom, which has its origins in hedgerow mead commonly drunk in the mediæval period. Burdock is believed to be a galactagogue, a substance that increases lactation, but it is sometimes recommended to be avoided during pregnancy based on animal studies that show components of burdock to cause uterus stimulation.
Folk herbalists considered dried burdock to be a diuretic, diaphoretic, and a blood purifying agent. The seeds of A. lappa are used in traditional Chinese medicine, under the name niubangzi (Chinese: 牛蒡子; pinyin: niúbángzi; Some dictionaries list the Chinese as just 牛蒡 niúbàng.)
Burdock is a traditional medicinal herb that is used for many ailments. Burdock root oil extract, also called Bur oil, is currently used in Europe under the belief that it is a useful scalp treatment. Modern studies indicate that burdock root oil extract is rich in phytosterols and essential fatty acids (including rare long-chain EFAs).
Burdock and Velcro
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 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 of his studies was Velcro.
- Arctium lappa: greater burdock, gobō
- Arctium minus: lesser burdock, burweed, louse-bur, button-bur
- Arctium tomentosum: downy burdock, woolly burdock
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