Suffruticose plants up to 1 meter high; stems subquadrangular, glabrous, the internodes up to 12 cm. long or more; leaf blades ob- long-ovate, up to 13 cm. long and 6 cm. wide, short-acuminate (the tip itself blunt), acute, obtuse or rounded at base, rather firm, undu- late or shallowly serrate, the teeth low (0.5 mm. long) and broad, the upper surface glabrous or nearly so, the lower surface puberulous, the hairs (up to 0.16 mm. long) confined more or less to the veins, the costa and lateral veins (about 6 pairs) prominent beneath, less so above, the veinlets coarsely reticulate, cystoliths not apparent; petioles rather slender, up to 3 cm. long, glabrous or sparingly puberu- lous; flowers borne in terminal panicles about 10 cm. long and 6 cm. broad, the lowermost internodes of the panicle about 2 cm. long, the others successively shorter toward the tip of the inflorescence, all glabrous and subquadrangular; bracts subtending the ultimate branches of the inflorescence linear, about 3 mm. long and 0.75 mm. wide, obtuse or rounded, glabrous, those subtending the flowers spath- ulate, 5 mm. long, 1.5 mm. wide near tip, narrowed to 1 mm. at 1.5 mm. below tip, obtuse, glabrous; bractlets lacking; calyx 2 cm. long, glabrous, the segments 5, lanceolate, up to 16 mm. long and 3.5 mm. wide, acute, the costa and 2 pairs of lateral nerves slender but rather prominent; corolla yellow, glabrous, up to 4.8 cm. long, the tube subcylindric, 7 mm. broad at base, narrowed to 3 mm. at 5 mm. above base, 6 mm. broad at mouth, the upper lip suberect, oblong, 1.8 cm. long, 5.5 mm. wide, bilobed at tip, the lobes triangular-ovate, 3 mm. long, 1.5 mm. wide at base, obtuse, incurved, the lower lip cuneate, about 12 mm. long, 11 mm. wide at base of lobes, the lobes triangular-ovate, 2.5 mm. long, the middle lobe 4.5 mm. wide, the lateral ones 3.25 mm. wide, all rounded and erose at tip, the middle one more or less emarginate; stamens exserted about 2 cm. above the mouth of the corolla tube, glabrous, the anthers 4 mm. long, the lobes
1 mm. broad, parallel (the connective narrow), subapiculate at base; style about as long as the stamens, glabrous; ovary glabrous, 4- ovuled; capsules not seen.
Type in the U. S. National Herbarium, No. 1950034, collected at Aguabonita, valley of the Rio San José, in the vicinity of Moscopán, Department of Cauca, Colombia, 2,280 meters altitude, January 30, 1947, by J. Cuatrecasas (No. 23467).
Fosberg's No. 20115 (US), collected in a wet forest on a flat ridge- top northwest of Quebrada la Candela, Río Naranjo, 20 km. southwest of San Agustín, Department of Huila, Colombia, 2,100 to 2,300 meters altitude, February 13, 1943, is also of this species.
Cuatrecasas gives on his label the following notes: "Suffrutex 1 met. Hoja verde brillante, haz verde grisaceo envés, peciolo y nervios violáceos. Caliz amarillo con márgenes verdosos. Corola amarilla. Anteras violetas."
Fosberg's collection was from an herb less than a meter tall with a yellow-green calyx and yellow corolla.
This species is doubtfully placed in the family Acanthaceae. Should it belong in the genus Jacobinia, the shallowly toothed leaves and the lack of cystoliths and bractlets would be unique. The specific name is from the Greek meaning ambiguous or doubtful.