Bidens pilosa is an annual species of herbaceous flowering plant in the daisy family Asteraceae.

It is native to the Americas but is widely distributed as an introduced species in other regions including Eurasia, Africa, Australia, South America and the Pacific Islands,[2] and is classified as an invasive species in some regions of the world.

[3][4] Bidens pilosa is a branched annual forb of gracile habit, growing up to 1.8 meters tall.

[7][8] It is an effective means of seed dispersal by zoochory, as the fruits are transported by animals.

[12][13][14] Its many English common names include black-jack,[15]: 819  beggarticks, hairy beggarticks, cobbler's pegs, devil's needles, hairy bidens, Spanish needle, farmers friend, Devils Pitchfork, hitch hikers and sticky beaks.

[16][17][18] Although Bidens pilosa is primarily considered a weed, in many parts of the world it is also a source of food and alternative medicine.