Herb, 15-100 cm tall, little branched. Stems and branches 0.1-0.5 cm in diam.; internodes 3.5-12.5 cm, shorter at base. Leaves usually much shorter than internodes; blade linear-triangular to ovate-elliptic, lower leaves broader, 0.5-6.6 x 0.3-1.5 cm, apex obtuse to acute (lower leaves) acute to acuminate (upper leaves), primary and (usually) secondary veins distinct. Inflorescence terminal, sometimes in upper leaf axils, 1-5(-10)-flowered modified dichasium; bracts (10-)25-55 mm, (almost always) as long as or longer than leaf pair below, bracteoles (15-)25-35 mm; pedicels 1-3 (rarely to 6-10 and then only lowest ones) mm long. Flowers erect to slightly nodding, almost all appear sessile (especially upper ones); calyx green, rarely dull maroon, 20-45 mm long, 4-ribbed or 4-winged, connation 1/2-3/4 of its length, lobes linear-narrowly triangular, 7-20 x 2-6 mm, as long as or longer than corolla tube (rarely shorter), margin entire, membranous, apex acuminate, ribs/keels 0.2-2 mm broad, wings 1.5-3.5 mm broad, wing venation transverse, sometimes very slight if any; corolla pink to mauve to light purple/lila to violet or white with purple lines, salver- to funnel-shaped, (25-)30-60 mm long, connation at least 2/3 of length, lobes round to very widely obovate, 12-21 x 10-17 mm, margin entire to slightly undulating, apex broadly rounded/obtuse and acuminate; stamens longest ones longer than corolla tube, 12-39 mm long, longest ones as long as or longer than style+stigma, unequal in length, sometimes 2 long 2 short, inserted on corolla tube at 1/3-1/2 from base, filaments white, sometimes violet-rose, 7-34 mm long, straight, flattened at basewith dentate appendages, up to 1/4 of length of filaments, anthers white, purple, or yellow, (narrowly) oblong-ellipsoid, 3.5-5 mm long; pistil 20-31 mm long, ovary narrowly oblong, 4-angled, 7-15 x 2-3 mm, disk-like ring absent, style 8-17 mm long, white or violet rose, as long as or longer than corolla tube, stigma white, rarely yellow, lobes transversely ovate-reniform, 2-3 mm long. Fruit narrowly ellipsoid, 10-18 mm long, calyx and corolla persistent.
Amazon, Cerrado and Atlantic forest present, Atures present, French Guiana present, Guianas present, Guyana present, Puerto Ayacucho present, Roraima territory present, Rupununi Savanna present, Southern America: Brazil North (Amazonas present); Venezuela (Venezuela present), Suriname present, along the coast, Sipaliwini Savanna present
Venezuela (Amazonas, Atures, Puerto Ayacucho), Guyana (Roraima territory, Rupununi Savanna), Suriname (along the coast, Sipaliwini Savanna), French Guiana (along the coast), Brazil (Amazon, Cerrado and Atlantic forest); 75 collections studied, of which 62 from the Guianas (GU: 19; SU: 19; FG: 24).