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.
















Habit
Erect, annual herb, 0.3‒1.8 m tall.
Leaves
Leaves pinnately compound, usually 2.5‒13.5 cm long including petiole, leaflets (1‒)3‒5(‒7).
Flowers
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.
Fruit
Achenes dark brown or black, straight, wingless, 8‒16 mm long, setose.
Chromosomes
2n = 24, 36, 46, 48, 72, ca. 76.
Contributor
Nancy Khan