[Coreopsis alba L.; Bidens alba var. radiata (Schultz-Bip.) Ballard ex Melchert; B. leucantha (L.) Willd.; B. pilosa L. var. radiata Schultz-Bip.]
(nat)
Erect annual or short-lived perennial herbs 0.3-1.5 m tall. Leaves simple or pinnately compound, usually 6-17 cm long including petiole, leaflets 1-3. Heads 3-18 in compound cymes terminating main stem and lateral branches, 2.2-4.2 cm in diameter including ray florets, peduncles 0.8-11 cm long; outer involucral bracts spatulate-tipped, (2-)4-5 mm long; ray florets 5-8 per head, sterile, rays white, 10-16 mm long; disk florets 26-69 per head, perfect; pappus of 2 awns 1-2 mm long. Achenes black, straight, wingless, 4-12 mm long, setose. [2n = 24, 48, 72.] Native from Florida to South America and the West Indies; in Hawaii only in recent years rapidly spreading in lowland disturbed areas on Kure Atoll, Midway Atoll, Kaua‘i, 0‘ahu, Maui, Kaho‘olawe, and Hawaii. First collected on 0‘ahu in 1958 (.Pearsall s.n., BISH).
Hawaiian plants are referred to var. radiata with stems erect and leaves pubescent. This species is closely related to B. pilosa and will hybridize with it experimentally, but natural hybrids have not yet been found in the Hawaiian Islands.