Wagner, Warren L., Derral R. Herbst and S. H. Sohmer. 1999. Manual of the Flowering Plants of Hawai'i (Bernice Pauahi Bishop Museum Special Publication, 2 Vol. Set). Honolulu, HI

Flora of Hawaii:  

Distribution    
In the Hawaiian Islands, endemic to Ni`ihau, Kaua`i, O`ahu.

Habit
Erect perennial or facultatively annual herbs 0.7-2.5 m tall, woody at base, with ascending lateral branches.

Leaves
Leaves pinnately or rarely bipinnately compound, usually 11-25 cm long including petiole, leaflets 5-11(-13), lanceolate, usually 3.5-7 cm long, 1.8-3.5 cm wide, glabrous or sparsely ciliate, margins coarsely serrate. 

Flowers
Heads more than 50 in open, compound cymes terminating main stem and lateral branches, 2.5-4.5(-5) cm in diameter including ray florets, peduncles 1-1.5 cm long, glabrous; outer involucral bracts 2.5-5.5 mm long, the inner ones distinct; ray florets 5(-7) per head, sterile, rays yellow, 15-21(-25) mm long (sometimes shorter on male-sterile plants), 4-6 mm wide; disk florets 17-21 per head, perfect or female(and then plants gynodioecious), corollas yellow; pappus of minute awns or absent. 

Fruit
Achenes black, straight to curved or twisted, wingless, 7-14 mm long, 0.5-0.8 mm wide, conspicuously long-tapered apically, tapering to 0.3 mm wide 1 mm below apex, setose near base and sometimes above.