What is "xanthium strumarium"

Xanthium \Xan"thi*um\, n. [NL., fr. Gr. xa`nqion a plant used for dyeing the hair yellow, said to be the Xanthium strumarium, from xanqo`s yellow.] (Bot.) A genus of composite plants in which the scales of the involucre are united so as to form a kind of bur; cocklebur; clotbur.

Xanthium strumarium (rough cocklebur, clotbur, common cocklebur, large cocklebur, woolgarie bur) is a species of annual plants belonging to the Asteraceae family. It probably originates in North America and has been extensively naturalized elsewhere.