Robust herbs up to 1.5 meters high, becoming more or less shrubby; stems subquadrangular, puberulous or the lower portions glabrate, the hairs up to 0.08 mm. long, mostly appressed; leaf blades oblong- elliptic or oblong-ovate, up to 22 cm. long and 8.5 cm. wide, short- acuminate (the tip itself obtuse), acute to subacute at base, moderately firm, entire or undulate, both surfaces minutely hirtellous, the hairs confined chiefly to costa and lateral veins (12 to 14 pairs), the hairs up to 0.13 mm. long, appressed or ascending, the costa, lateral veins and the coarsely reticulated veinlets prominent beneath, less so above, the cystoliths prominent, up to 0.2 mm. long; petioles up to 4 cm. long and 1.5 thick, minutely and inconspicuously hirtellous; flowers borne in short subhelicoid cymes, 4 to 8 at each node, these forming dense cylindric terminal panicles up to 22 cm. long and 4 cm. broad, the lowermost node of the inflorescence bearing a pair of ovate leaves up to 9 cm. long and 4 cm. wide, these sharply acuminate at tip, rounded at base, the node above this separated by an internode as much as 6 cm. long and subtended by ovate foliose acuminate subsessile bracts up to 2.5 cm. long, the subsequent internodes successively shorter and the corresponding foliose bracts smaller toward tip of panicle, the lower internodes of the rachis puberulous, the upper rather densely hirtellous with subappressed or ascending septate hairs up to 0.32 mm. long, the pedicels stout, 1 to 3 mm. long, appressed hirtellous, erect; bracts subtending the flowers linear-subulate, up to 5 mm. long and about 0.5 mm. wide, acute, sparingly hirtellous; calyx segments lanceolate, 6.5 mm. long, 1 mm. wide at base, gradually narrowed to an acute tip, sparingly hirtellous, the hairs subappressed, mostly borne toward the tip, 0.2 mm. long; corolla violet-purple, recurved, glabrous, the tube 8 mm. long, about 4 mm. broad at base, narrowed to 2.5 mm. at throat, the upper lip erect, linear, 1 cm. long, 1.25 mm. wide, subacute, the lower lip spreading-ovate, 1 cm. long, 0.5 mm. wide, rounded and subtruncate at tip and 3-lobed, the lobes low, 0.75 mm. long and 1 to 1.5 mm. wide, rounded at tip; stamens glabrous, re- curved, exserted 7 mm. beyond the mouth of the corolla tube; anthers 5 mm. long, 1.5 mm. thick; style exserted 2.5 cm. beyond the mouth of the corolla, violet-purple, glabrous, the stigma lobes ovate, minute; Ovary glabrous; capsules not seen.
Type in the U. S. National Herbarium, No. 1853812, collected at Los Cárpatos, in the valley of the Rio Cali, Department of El Valle, Colombia, about 2,000 meters altitude, November 3, 1944, by J. Cuatrecasas (No. 18515).
Also of this species are Cuatrecasas' No. 23929, collected at Las Colonias, above Queremal, valley of the Río Digua, Department of El Valle, 1,950 to 2,050 meters altitude, March 20, 1947, and J. M. Duque's No. 1660 collected at El Recuerdo, valley of the Río Cali, 1,600 to 1,800 meters, June 15, 1938.
Habracanthus pycnostachys should be easy to recognize by its narrow cylindric panicles with recurved, violet-red flowers. The label of the type bears the following field notes: "Hierba robusta, 1.5 m. Hoja verde haz, verde envés. Brácteas verdes. Raquis, pedúnculo y cáliz purpúreo violáceo oscuro. Corola violeta rojiza oscuro. Fila- mentos y estilo id." The label on Duque's sheet bears the following data: "Arbusto de 1 metro de altura, leñosos, y notable por sus bellas flores rojizas y digno de ser cultivado en jardines."
The specific epithet is from the Greek words Tuкvós, close and com- pact, and σráxus, spike, in allusion to the narrowed dense panicle.