Flora of the Hawaiian Islands
Dicotyledon Literature for Bidens pilosa
Wagner et al., 1990, 1999; Lorence & Wagner, 2020.
   Asteraceae -- The Sunflower Family Bibliography
      Bidens pilosa

Common name(s): beggartick, ko`oko`olau, ko`olau, Spanish needle, ki, ki nehe, ki pipili, nehe
General Information
DistributionNative to tropical America, but now a pantropical weed.In the Hawaiian Islands, naturalized on Midway, Ni`ihau, Kaua`i, O`ahu, Moloka`i, Lana`i, Maui, Kaho`olawe, Hawai`i.

Erect, annual herb, 0.3‒1.8 m tall.
Leaves pinnately compound, usually 2.5‒13.5 cm long including petiole, leaflets (1‒)3‒5(‒7).
Heads 21‒42 in compound cymes terminating main stem and lateral branches, discoid and 0.5‒1 cm in diameter or radiate and < 10 mm in diameter excluding ray florets, peduncle 1‒9 cm long; outer involucral bracts spatulate tipped, 2.5‒5 mm long; ray florets absent or 4‒7 per head, rays white or pale yellow, 2‒8 mm long; disk florets 35‒75 per head, perfect, corollas yellow; pappus of 2‒3(‒5) barbed awns 1‒2 mm long.
Achenes dark brown or black, straight, wingless, 8‒16 mm long, setose.
2n = 24, 36, 46, 48, 72, ca. 76.
Nancy Khan