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Family: Acanthaceae
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Herbs or suffrutescent plants; stems branching, subquadrangular, the angles rounded, the lower portions shallowly grooved, glabrous, the upper parts bifariously hirtellous, the hairs white, variously curved, up to 0.45 mm. long; leaf blades lanceolate, up to 6.5 cm. long and 12 mm. wide near base, gradually narrowed to an acute tip, narrowed or obtuse at base and briefly decurrent on the petiole, coriaceous, entire or undulate, glabrous or the costa and marginal regions sparingly hirtellous, the hairs on the costa curved, subap- pressed, up to 0.24 mm. long, those on and near the margins of the leaf blades rigid, mostly ascending and about 0.08 mm. long, the costa, lateral veins (about 7 pairs) and the coarsely reticulated veinlets prominent on both surfaces of the leaf blade, the cystoliths not apparent; petioles 1 to 3 mm. long, finely puberulous with subappressed hairs; flowers borne in dense spikes 1 to 2.5 cm. long and 5 to 10 mm. broad, these terminating the branches, the rachises minutely puberulous with more or less curved hairs, only a few of which exceed 0.16 min. in length; peduncles up to 3 cm. long, bifariously puberulous with curved hairs; bracts narrowly lanceolate, 4.5 mm. long, 0.5 mm. wide near the middle, acute, sparingly and minutely hirtellous and ciliate, the costa prominent; bractlets subulate, 5 mm. long, 0.25 mm. wide at base, the hairs and costa similar to those of the bracts; calyx seg- ments 5, lanceolate, 5.5 mm. long, 0.5 mm. wide near base and middle, thence narrowed into a slender tip, sparingly and minutely hirtellous and ciliate, the hairs up to 0.08 mm. long; corolla 8 mm. long, the upper part finely and rather sparingly pubescent, the lower part glabrous, the tube 1.5 mm. broad at base, 2 mm. broad at the throat, the upper lip rather narrowly ovate, 6 mm. long, 2 mm. wide at base, narrowed from middle to a minutely bilobed tip 0.5 mm. wide, the lobes 0.25 mm. long, obtuse, the lower lip subovate, about 6 mm. long and 4 mm. wide, rather shallowly 3-lobed at tip; stamens about 3 mm. long, slightly exserted, the filaments slender, glabrous, the anther cells super- posed, 0.75 mm. long, 0.25 mm. thick, minutely pilose dorsally, the connective 0.25 mm. wide; capsules clavate, 7 mm. long, the seed- bearing part 4 mm. long, 3 mm. broad and about 2 mm. thick, the surface rather densely pubescent, the hairs spreading near tip, retrorse toward base of capsule; retinacula 1.5 mm. long, the tip thin, oval, cucullate. Type in the U. S. National Herbarium, No. 2124584, collected along the Río Piraparaná, a tributary of the Río Apaporis, Comisaría of Vaupés, September 18, 1952, by Richard Evans Schultes and Isidoro Cabrera (No. 17545). Isotype: US. The color of the corolla is not apparent in the dried material. The specific epithet is from the Greek xuros, leather, and púλλov, leaf, in allusion to the coriaceous texture of the leaf blade |