Decumbent herbs up to 1.5 meters long; stems sparingly branched, subquadrangular, glabrous or sparingly pilose in two lines, the hairs up to 0.38 mm. long, the stipular lines between the bases of the petioles densely pilose, the hairs white, straight, ascending, up to 0.7 mm. long, the cystoliths numerous, parallel, up to 0.16 mm. long, obscure; leaf blades oblong-ovate, up to 14 cm. long and 4 cm. wide, slenderly falcate-acuminate (the tip itself blunt), narrowed and cuneate at base and decurrent on the petiole, both surfaces minutely strigose, the hairs confined to costa and lateral veins (6 or 7 pairs), up to 0.7 mm. long, the venation moderately prominent, the cystoliths conspicuous, up to 0.16 mm. long; petioles 5 to 10 mm. long, glabrous or sparingly pilose beneath, the channels and margins densely pilose; flowers solitary in the axils of the upper leaves, each subtended by a pair of leaflike bracts, these oblong-lanceolate, up to 2 cm. long and 5 mm. wide, acute; pedicels 1 mm. long, stout; calyx segments nar- rowly lanceolate, subequal, 16 to 20 mm. long, 1.75 mm. wide, grad- ually narrowed to a slender tip, the margins densely ciliate with white spreading or ascending hairs up to 1.5 mm. long, the inner surface glabrous, the outer rather sparingly pilose toward tip; corolla 6 cm. long, white (?), sparingly pubescent, the hairs confined to the nerves, spreading, up to 0.75 mm. long, the tube 3 mm. broad at base, grad- ually narrowed to 2 mm. at 2 cm. above base, thence abruptly enlarged to 16 mm. at throat, the enlarged portion about 2.5 cm. long and somewhat ventricose, the lobes suborbicular, about 12 mm. in diam- eter; stamens included, the longer pair 2 cm. long, the shorter 1.5 cm. long, the filaments glabrous except at base, here minutely puberu- lous, the anthers 4.5 mm. long, 1.5 mm. broad; style slightly exceeding the stamens in length, glabrous except at base, here puberulous, the stigma lobes very unequal, one linear, 2.25 mm. long and 0.3 mm.

wide, the other ovate, rounded, about 0.75 mm. long and wide; capsule not seen.

Type in the Herbarium of the University of California, No. 941780, collected in dense forest on north bank of the Río Guejar near its junction with the Río Zanza, at the northern end of the Cordillera Marcarena, Intendencia of Meta, 500 meters altitude, August 20, 1950, by S. Galen Smith and Jesús M. Idrobo (No. 1486). Isotype: US. Ruellia macarenensis resembles in a general way R. puri Mart. of Brazil, but that species has longer corollas with a much more slen- der tube (lower narrow portion 1 mm. broad and as much as 5 cm. long and the expanded upper portion about 1 cm. long and 5 mm. wide at mouth) and its leaf blades are less slenderly acuminate and falcate. The plants from which the type specimens were obtained were hanging from the steep river bank. They were sparingly branched and were from 0.5 to 1.5 meters long.