Plants herbaceous or suffrutescent; stems quadrangular, shallowly sulcate, the angles narrowly winged, the wings pilose, the hairs barely 1 mm. long, the cystoliths minute; leaf blades oblong-ovate, up to 17 cm. long and 7 cm. wide, rather slenderly acuminate, narrowed at base and decurrent on the petiole, thin, shallowly crenate, glabrous except the costa, lateral veins (10 pairs), and the margins, these pilose, the hairs about 0.5 mm. long, spreading or subappressed; petioles up to 3 cm. long, minutely pilose; flowers borne on axillary dichotomously branched peduncles, these up to 11 cm. long to the first fork, flattened, the edges pilose with white spreading hairs 0.5 mm. long, the secondary peduncles 1.5 to 3 cm. long, flattened or obscurely quadrangular, the narrowly winged edges pilose with white spreading hairs 0.5 to 0.75 mm. long or when young the entire surface pilose; bracts narrowly ob- long, narrowed at both ends, up to 14 mm. long and 4 mm. wide, but usually smaller, the margins pilose; pedicels slender, up to 14 mm. long, glabrous; calyx 8 to 10 mm. long, divided nearly to base, the segments subulate, 0.75 to 1 mm. wide at base, ciliate, the hairs about 0.25 mm. long; corolla 2.5 cm. long, white, glabrous, the lower portion of the tube slightly curved, about 2 mm. broad from base to 5 mm. above base, thence gradually enlarged to 7 mm. at throat, the enlarged por- tion slightly ventricose, the lobes ovate or elliptic, about 8 mm. long and 5 mm. wide, rounded, shallowly to rather deeply emarginate; sta- mens barely exserted; capsules clavate, glabrous, 1.5 cm. long, the solid stipitate base about 6 mm. long, the seed-bearing portion about 3 mm. broad, each capsule usually maturing 4 seeds, these ovate, flat- tened, about 3.5 mm. long and 2.5 mm. broad, the margins puberulous; retinacula slender, sharply curved or bent at an angle. Type in the National Herbarium of Colombia, collected in pasture lands at Armero, in the Magdalena Valley, Department of Tolima, Colombia, 400 meters altitude, October 6, 1940, by J. Cuatrecasas (No. 10529a). Fragment of type in the U. S. National Herbarium, No. 1854310. The name alludes to the Department of Tolima, where the type was procured. Ruellia tolimensis is closely related to R. potamophila but can be separated by the pilose peduncles, these once instead of 2 or 3 times branched, and by the more numerous veins of the leaf blades (10 pairs instead of 8).