a, section of flower-head, showing hooked bracts.
Burdock (Arctium), a genus of Compositæ (q.v.), familiarly characterised by the bracts of the involucre which are hooked inwards at the point. By means of these hooks, the flower-head, popularly called a bur, readily lays hold of the clothes of a passer-by, the wool of a sheep, or the like, and thus the fruitlets are transported from one place to another, the short hairy pappus being insufficient to waft them far on the wind. The Common Burdock (A. Lappa) is consequently of wide distribution throughout the north temperate zone, and has numerous varieties or sub-species; it is very common in the United States. It flowers in July and August. The root was formerly used in medicine, and the young shoots for culinary purposes, for which it has even attained cultivation in Japan.