Herb, up to 1.5 m high, unbranched to sparsley branched. Stems and branches up to 0.6(-1) cm in diam., quadrangular, winged, wings 0.6-3.7 mm wide; internodes 0.7-15 cm long. Leaves sessile, cauline evenly; blade membranaceous, ovate to elliptic, obovate, 1.3-13.8(-20.2) x 0.5-4.7(-8.5) cm, margin not thickened, flat, apex acute to obtuse, base cuneate or attenuate (often 2 most apical leaf pairs connate to fully perfoliate). Inflorescence 2-33-flowered; bracts ovate, 1.6-6.5 mm long, apex acute; pedicel 2-7 mm long. Flowers erect; calyx green, 6-10 x 4-7 mm, lobes orbicular, 3-5 x 3-5 mm, margin membranaceous, apex obtuse; corolla greenish white, cream, to pale yellow, with dark green spot on apex of each corolla lobe, tubular to salver-shaped, 19-40 mm long, 8-20 mm wide at mouth, lobes ovate, 3-6 x 3-7 mm, apex obtuse; stamens not exserted, positioned deep within corolla tube, filaments 8-15 mm long, straight, anthers white, elliptic to slightly ovate, 1.6-3 mm long, straight or curved after anthesis; pollen exine differentially reticulated; pistil 17-26 mm long, ovary 5.7-6.6 x 2.2-4.3 mm, style ca. 14 mm long, stigma lobes ovate, obovate, oblong, 2.5-5.1 x 1.8-2.0 mm. Fruit erect to horizontal, brown, ellipsoid, 11-20 x 4-10 mm; seeds brown, 0.1-0.4 mm in diam.
Brazilian Amazon present, French Guiana present, Guianas present, Guyana present, Southern America: Colombia (Colombia present); Costa Rica (Costa Rica present); Venezuela (Venezuela present), Trinidad present
Costa Rica, Colombia, Venezuela and Trinidad, Guyana, French Guiana, Brazilian Amazon; 84 collections studied, of which 8 from the Guianas (GU: 7; FG: 1).
This species has been listed in Guyana for "for removing worms and 'dirt' in the body" (Riley 8).
Herba caule valde quadrangulato vel quadrialato, foliis sessilibus ovatis ellipticis obovatisve apice acutis vel obtusis, corolla viridi-alba vel pallide lutea hypocrateriformi cum structuris sexualibus in fauce profunde confertis post anthesin decidua, capsulis maturis horizontaliter patentibus vel erectis.