Subshrubs up to 130 cm. high; stems subquadrangular, glabrous or inconspicuously and sparingly appressed-pilose, the hairs up to 0.48 mm. long, the cystoliths parallel, up to 0.35 mm. long; leaf blades oblong-ovate or oblong-elliptic, up to 10 cm. long and 7 cm. wide, subacute or short-acuminate (the tip itself blunt), gradually narrowed to an acute base and decurrent on the petiole, thin, entire or undulate, the upper surface sparingly hirsute, the hairs curved, ascending, up to 0.32 mm. long, whitish, septate, the lower surface. glabrous, the costa and lateral veins (10 to 12 pairs), prominent beneath, less so above, the cystoliths scattered but large and nearly straight, up to 0.27 mm. long; petioles (unwinged portion) up to 6 cm. long, 1 to 1.5 mm. thick, glabrous or the channels hirtellous, the hairs ascending or subappressed, the cystoliths large, conspicuous and parallel; panicles narrowly ovoid, rather lax, up to 30 cm. long and 11 cm. broad, broadest below middle and gradually narrowed to tip, the peduncle about 6 cm. long, hirtellous, the lowermost internode of the inflorescence 2 cm. long, the others successively smaller towards tip, the branches slightly curved, usually (except the uppermost) forked, these and the main rachis densely pilose with straight spreading acute glassy hairs 0.16 mm. long, these inter- mixed with longer glandular ones up to 0.64 mm. long, the flowers usually 8 or fewer to a branch, erect, the pedicels up to 3 mm. long, the pubescence that of the branches; calyx 4 to 7 mm. long, becoming 10 to 12 mm. long at maturity, deeply segmented, the segments lanceolate, in flower 4 to 6 mm. long, in fruit 11 mm. long, 1 mm. wide near base, thence gradually narrowed to a slender tip, puberulous and pilose, the hairs spreading, the small ones ca. 0.07 mm. long, numerous, rigid, glassy and blunt tipped or acute, the large ones up to 0.73 mm. long, rather scattered, blackish, gland-tipped; corolla 1.5 to 2 cm. long, glabrous, scarlet with yellow tip, 2 to 2.5 mm. broad at base, abruptly enlarged at 3 mm. above base to 7 mm., thence narrowed to 4 mm. at throat, the upper lip narrowly obovate, erect, more or less recurved, 3 to 4 mm. long, about 1.25 mm. wide, obtuse and entire at tip, the lower lip broadly ovate, about 3 mm. long and 5 mm. wide, the lobes suborbicular, about 2 mm. long and 2.5 mm. wide; stamens exserted 10 to 15 mm. beyond the lips of the corolla, glabrous, the anthers linear, 4 mm. long, 0.75 mm. broad, slightly curved; capsule clavate, 12 to 13 mm. long, 4 mm. broad, 3 mm. thick, the solid basal stipe about 3 mm. long, finely pubescent, the hairs slender, curved and ascending; retinacula 3 mm. long, slender from an enlarged base, the tip subobtuse; seeds 4, flat, blackish, suborbicular, 3 mm. long, 2.5 mm. broad, the tip tuberculate. Type in the U. S. National Herbarium No. 2045439, collected in subtropical forest on the Sierra Perijá, 6 km. east-northeast of Manaure, 42 km. east of Valledupar and 7 km. from the Venezuelan border, Department of Magdalena, Colombia, 1,735 meters altitude, February 1, 1945, by Martin L. Grant (No. 10731). Isotype: US. Oscar Haught's No. 4510 (US), collected in "Africa," Sierra Perija, Department of Magdalena, Colombia, about 1,500 meters altitude, December 16, 1944, is also of this species. Haught states in his label data that his plant was an erect herb up to 1.5 meters high, the flowers very showy, either all red, or red tipped more or less with bright yellow (in some plants more than half the corolla yellow), and that the species was very abundant locally, growing along streams and on moist slopes.
Habracanthus antipharmacus with its bicolored corollas suggests at once Lindau's H. diversicolor. The two species are closely related but if carefully compared show certain differences. In H. diversicolor the leaf blades are rounded above the winged petiole instead of being gradually narrowed into the petiole wing, and the inflorescence is denser with the shorter ascending rigid branches, the branches of the forks widely spreading. In H. antipharmacus the branches are slender, spreading, recurved, and the branches of the forks are only slightly spreading and longer and more slender.
Grant tells us that the root is used as a remedy for snake bite, thus suggesting the specific epithet, àvre, against, and papuакov, venom.