Stem subquadrangular, glabrous or sparingly and bifariously pi- losulous near nodes; leaf blades oblong-elliptic, up to 12 cm. long and 4 cm. wide, slenderly short-acuminate, (the tip itself blunt to acute). rather firm, crenate or shallowly dentate, glabrous or the costa of the upper surface bearing a few small hairs, both costa and lateral veins (6 or 7 pairs) prominent; cystoliths prominent under a lens; petioles 1 to 2 cm. long, glabrous or the margins ciliate; flowers several, borne in subcapitate clusters or on short bifurcate branches terminating the long slender peduncles, these up to 15 cm. long, glabrous, flattened, narrowly winged, more or less curved, the branches, when present, 5 to 15 mm. long; bracts linear-lanceolate, 14 mm. long, 4 mm. wide or less; pedicels 5 mm. long, slender, glabrous; calyx 5 mm. long, glab- rous except the sparingly ciliolate segments, these subulate, 3 mm. long and about 0.5 mm. wide; corolla red, 3 cm. long, curved, glabrous, the tube cylindric and about 2 mm. in diameter for about 7 mm. of its length, thence enlarged to a ventricose funnelform throat about 1 cm. broad, the limb 3 cm. broad, the lobes oblong, 14 mm. long and 8 mm. wide, rounded; stamens exserted about 5 mm. beyond the mouth of the corolla tube, the anthers linear, 3.5 mm. long, about 0.5 mm. wide; style slender, exserted about 2 cm. beyond the corolla tube; ovary glabrous; fruit not seen. Type in the herbarium of the Riksmuseet, Stockholm, collected in woods along the Río Timbío, Department of Cauca, Colombia, 1,100 meters altitude, September 15, 1938, by Kjell von Sneidern (No. 2647). A specimen collected by Triana, s. n. (S), in the vicinity of Popayán, Cauca, also represents the species. Ruellia caucensis is closely allied to R. ischnopoda, from which it differs chiefly in its glabrous character and in its much smaller calyx.