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     
Pantropical in littoral habitats, although apparently native only to the Old World. In the Hawaiian Islands, indigenous to Ni`ihau, Kaua`i, O`ahu, Moloka`i, Lana`i, Maui, Hawai`i.

Habit
Trees or arborescent shrubs 5-10(-20) m tall, bark gray, shallowly fissured.

Leaves
Leaf blades shiny yellowish green, ovate to deltate or orbicular, 5-30 cm long, glabrous, usually obscurely glandular punctate, lower surface with an elongate gland on midrib near base, apex usually acuminate, base cordate, petioles usually more than 1/2 as long as blades.  

Flowers
Flowers spreading, pedicels thick, shorter than subtending petioles; involucral bracts 3, lanceolate, 4-17 mm long, early deciduous; calyx cup like, essentially truncate, 8-12 mm long at anthesis, enlarging and flattening in fruit; petals yellow, usually with a maroon spot at base, obliquely obovate, crinkled apically, 4-7 cm long; staminal column included, yellow, up to 3 cm long, densely antheriferous for most of its length; style 5 grooved and twisted.  

Fruit
Capsules depressed globose, leathery, obscurely 5 angled, 2.5-4.5 cm in diameter, dehiscing irregularly with age.  

Seeds
Seeds grayish brown, 8-15 mm long, glabrate to densely brown pubescent.  

Chromosomes
2n = 24, 26, 28.