Shrub; stems glabrous or finely and bifariously puberulous, the hairs white, appressed or ascending, up to 0.25 mm. long; leaf blades ovate, up to 35 cm. long and 10.5 cm. wide or more, short-acuminate (the tip probably blunt), rounded near base to a width of 3 cm., thence gradually narrowed and decurrent on the petiole, rather thin, crenate, the upper surface subnitid, glabrous or sparingly hirtellous except costa and lateral veins (about 15 pairs), these rather densely puberulous with appressed hairs up to 0.5 mm. long, the scattered hairs of the intercostal areas ascending, the cystoliths minute, in- conspicuous and scattered, 100 to 150μ long, the lower surface glabrous or nearly so, minutely papillose under a lens, the cystoliths numerous and conspicuous, the costa and lateral veins prominent, much more so than above, the veinlets coarsely and rather conspicuously reticu- late; petioles (wingless portion) up to 5 cm. long, glabrous beneath, the channel pilose, the hairs ascending, septate, up to 0.5 mm. long; flowers borne in narrow spikelike panicles up to 20 cm. long and 5 cm. broad (near base), the peduncle up to 4 cm. long, its pubescence that of the stems, the rachis densely hirtellous, the hairs brownish, variously curved, up to 0.5 mm. long, the lowermost internode about 12 mm. long, the others successively shorter toward tip of the in- florescence, the lowermost flowers several, borne on branches about 10 cm. long, the uppermost flowers sessile, solitary, the pedicels about 2 mm. long, hirtellous, the lowermost pair of bracts leaflike, lanceo- late, up to 14 mm. long and 6 mm. wide, acuminate, the succeeding pair of bracts firm, narrowly lanceolate, keeled, 13 cm. long, 3 mm. wide at base, gradually narrowed to a slender tip, glabrous or spar- ingly hirtellous, ciliate, the marginal hairs about 0.25 mm. long, ascending, the other bracts thin, lanceolate, 9 mm. long and 3 mm. wide, successively smaller toward tip of inflorescence, all acute, with about 3 pairs of delicate nerves, glabrous or sparingly hirtellous, ciliate, the lateral pair of bracts, those subtending the flowers, similar but somewhat smaller; calyx crimson, 25 mm. long, deeply segmented, the segments lanceolate, 5 mm. wide, sharply acute, thin, delicately nerved, glabrous or sparingly hirtellous at tip, marked by slenderly linear parallel cystoliths; corollas 5 to 6 cm. long, crimson, distantly punctate, sparingly hirtellous except towards tip, here densely so, the hairs about 0.25 mm. long, some of them septate, the corolla tube about 1 cm. broad from near base to mouth, the upper lip erect, narrowly lanceolate, 2 cm. long, 5 mm. wide at base, the lower lip triangular, recurved, 12 mm. wide at base, narrowed to a slender 3-lobed tip, the lobes ovate, about 1 mm. long and 0.75 mm. wide; stamens exserted 15 mm. beyond mouth of corolla tube, the filaments flat, glabrous or bearing several minute hairs near base; anthers 6 mm. long, 1.5 mm. broad, rounded at tip and base, glabrous; style reaching tip of the upper corolla lip, glabrous, the stigma conical; ovary glabrous; capsules not seen.
Type in the U. S. National Herbarium, No. 1798547, collected in damp forests between Achipayaco and Mocoa, Comisaría of Putu- mayo, Colombia, 450 to 500 meters altitude, December 25, 1940, by J. Cuatrecasas, No. 11271.
When compared with K. rostellata, Kalbreyeriella gigas is easily recognized by its dense narrow panicle, large crimson calyces and remarkably large leaf blades. The specific epithet, gigas, is from the Greek yiyas meaning giant, in allusion to the large size of the plants of this species.