Burdock seed

Great burdock is a biennial plant with huge, heart-shaped leaves and a tall flowering stem with globe-shaped purple thistle-like flower heads. The heads are covered in hooked bracts, which form burs that stick to clothing and animal fur after flowering.

Inside each bur are many small, curved, grey-brown to mottled seeds, which are botanically one-seeded fruits called achenes, about five to seven millimetres long, with a dark top.

They taste slightly bitter and oily. The seeds are sold in herbal shops as dried whole fruit or crushed pieces, usually under the Chinese pharmaceutical name Arctii Fructus, and are not a common culinary seed.

Arctium lappa is native to temperate Europe and Asia, and was carried widely, becoming naturalised in North America, Australia and elsewhere. It prefers disturbed ground, roadsides and field edges.

The plant has been cultivated for its long taproot, especially in Japan, where it is known as gobo. The seed fruits are collected from wild and cultivated plants in China and neighbouring countries.

The genus name Arctium comes from the Greek arktos, meaning bear, in reference to the rough, shaggy burs, and lappa is from a Latin word for a bur. The English burdock combines bur with dock, a name for a broad-leaved plant.

Burdock was known to Greek and Roman writers and appears in medieval European herbals as a remedy for skin complaints, wounds and digestive upsets. It is, in the popular imagination, the plant behind the invention of hook-and-loop fastening: Swiss engineer George de Mestral examined burs stuck to his dog's fur in the 1940s, and went on to develop Velcro.

In Chinese medicine, burdock fruit, niubangzi, has been used for more than a thousand years, recorded in classical materia medica for sore throat, colds with rash, and swelling, usually combined with other herbs.

The root became a vegetable in Japan, and the plant was grown for it in Europe during the Middle Ages. Burdock root beer and dandelion and burdock, a traditional British soft drink, derive from European herbal drinks.

Modern research has focused on lignans in the seeds, such as arctigenin and arctiin, in laboratory and small animal studies.

In traditional Chinese medicine, the dried, sometimes stir-fried fruit is simmered in herbal decoctions for sore throats, coughs and skin eruptions, and is a typical component of formulas for colds. It is also used in some Japanese kampo preparations.

Seeds are not a common food, but they have been pressed for oil in some regions, and the root is boiled, braised or pickled as a vegetable in East Asia.

Burdock seed is also used in hair-care preparations, and the plant is gathered for traditional teas and tonics.

Burdock fruit contains lignans such as arctigenin and arctiin, as well as fatty oil and caffeic acid derivatives. Laboratory and animal studies suggest anti-inflammatory, antiviral and blood sugar-lowering effects, but there are few well-designed clinical trials in people.

Traditional use for sore throat and skin conditions is long established, but should not be relied on in place of medical care for serious infections.