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, Republic of: present Puerto Ayacucho: present Roraima territory: present Rupununi Savanna: present Southern America:, Brazil North (Amazonas ‒ present); Venezuela (Venezuela ‒ present) Suriname, Republic of: 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).