Arctium is a genus of biennial plants commonly known as burdock, family Asteraceae. Native to the Old World, several species have been widely introduced worldwide. Plants of the genus Arctium have dark green leaves that can grow up to 70 cm (28 in) 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.
Burdock flowers provide essential pollen and nectar for honeybees around August when clover is on the wane and before the goldenrod starts to bloom. Burdock root extract, 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 used for many ailments. Burdock root oil extract, also called Bur oil, is used in Europe as a scalp treatment. Modern studies indicate that burdock root oil extract is rich in phytosterols and essential fatty acids (including rare long-chain EFAs).
The green, above-ground portions may cause contact dermatitis in the individual with allergies as the plant contains lactones.