Herbs to 2 m tall, erect, nearly isophyllous. Stems 4-angled, densely white pubescent with gland-tipped trichomes, glabrescent. Petiole 2-13 cm, gland-tipped pubescent, glabrescent, apically winged; leaf blade ovate to orbicular, 7-22 × 4-18 cm, pubescent especially along veins, cystoliths abundant on both surfaces, secondary veins 9-11 on each side of midvein, base cuneate, rounded, or sometimes subcordate and decurrent onto petiole, margin deeply dentate or serrate, apex acute to acuminate. Inflorescences axillary, spikes, to 15 cm, secund, sometimes reduced to single flowers; peduncle 0.5-7 cm, densely gland-tipped pubescent; rachis somewhat zigzag; bracts at base of spike leaflike, petiolate, ovate, to 4 × 2 cm, gland-tipped pubescent, base cuneate, margin serrate, apex obtuse; bracts toward spike apex lanceolate, diminishing apically to ca. 10 × 1 mm, margin entire, apex obtuse; bracteoles linear-oblanceolate, ca. 7 × 1 mm, gland-tipped pubescent, apex obtuse. Flowers usually 1 per node, 0.8-2.5 cm apart on rachis. Calyx 1.2-2.1 cm, densely gland-tipped pubescent, 5-lobed almost to base; lobes linear-oblanceolate, apex obtuse; one lobe to 2 mm longer than others. Corolla purplish blue, 4-5 cm, ventricose, outside sparsely white pubescent, inside pubescent; tube basally cylindric and narrow for ca. 5 mm then bent to ca. 90°, strongly ventricose, and widened to ca. 1.5 cm at mouth; lobes oblong, ca. 6 × 5 mm, apex obtuse. Stamens 4; filaments glabrous, shorter pair ca. 2.5 mm, longer pair ca. 4 mm; anther thecae oblong, ca. 2.5 × 1 mm; pollen type 4. Ovary glabrous; style ca. 2.2 cm, shortly pilose. Capsule oblong, ca. 15 × 2-3 mm, glabrous except for very few stalked glands near apex, 4-seeded. Seeds blackish brown, elliptic in outline, 3-3.5 × ca. 2.5 mm, densely pilose; areola very small. Fl. Jul-Sep, fr. Oct-Dec.
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