Bidens pilosa

Bidens pilosa is a species of flowering plant in the aster family. It is native to the Americas but it is known widely as an introduced species of other regions, including Eurasia, Africa, Australia, and the Pacific Islands. It is a tall branched weed with thin yellow flowers that develop into a cluster of barbed seeds. Its many common names include black-jack, beggar-ticks, cobbler's pegs, and Spanish needle. The seeds are like short, stiff hairs. They...