Spanish needle
Bidens pilosa L. [Asteraceae]
Kosendangusa (コセンダングサ, 小栴檀草)
Lifeform: weedy annual forb
Distribution: extotic worldwide, including Japan (probably originating from Southt Africa)
Habitat: ruderal, such as roadsides
Seed dispersal: animal (external) by hooked barbs
Chromosome number: 2n = 24, 36, 48, or 72
Varieties
var. bisetosa S. Ohtani et S. Suzuki (アワユキセンダングサ)
var. minor (Blume) Sherff (コシロノセンダングサ/シロノセンダングサ)
var. pilosa (コセンダングサ, s.s.)
var. radiata Sch. Bip. (タチアワユキセンダングサ)
Bidens pilosa in Japan
[1] a patch. [2] close-up of a head. [3] seeds. At Yodogawa Riverside Park, Osaka, on October 29 2011.