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 Moloka`i.

Habit
Apparently scandent perennial herbs; stems quadrangular, glabrous or sparsely pubescent in grooves. 

Leaves
Leaves membranous, ovate to elliptic, 4.2-10 cm long, 1.7-3.6 cm wide, glabrous except pubescent on midrib, margins serrate, apex acute, base truncate to obtuse, petioles 5-20 mm long, sparsely hirsute.  Flowers  

Flowers
Flowers 2-6(-8) per verticillaster, pedicels 3-4 mm long, puberulent; calyx radially symmetrical, narrowly campanulate, 8-12 mm long, nearly glabrous, the teeth linear-lanceolate, 5-8 mm long, 1-1.5 mm wide at base; corolla pubescent externally, tube apparently pale yellowish green, nearly straight, ca. 10-16 mm long, lobes pale brown, upper lip ca. (3-)4-6(-9) mm long, lower lip ca. 2-4 mm long.   

Fruit
Nutlets ca. 2.5-3 mm long.