Perennials 40-50 cm tall. Roots to 30 × 2 cm. Stems erect, stout, simple, glabrous. Basal leaves petiole 5-7 cm, membranous; leaf blade narrowly elliptic to ovate-elliptic, 9-16 × 4-5.5 cm, base narrowed, margin scabrous, apex acuminate to acute, veins 7-9. Stem leaves 3-5 pairs; petiole to 3.5 cm, membranous; leaf blade elliptic-lanceolate to ovate-elliptic, 9-16 × 4-5.5 cm, base obtuse to subtruncate, margin scabrous, apex acuminate to acute, veins 3-5; upper leaves distinctly larger, sessile, spreading, and surrounding flower cluster. Inflorescences crowded into terminal clusters, many flowered, rarely also in few-flowered axillary whorls. Flowers sessile. Calyx tube spathelike, 6-8 mm, membranous, split on 1 side, apex truncate; lobes 5, dentiform, 0.3-0.5 mm. Corolla inside pale yellow to yellow-green; limb outside tinged dark brown, broadly tubular, (2.6-)3-3.2 cm; lobes ovate-tri-angular, 4-5 mm, margin entire, apex acute; plicae triangular, 0.5-1.5 mm, oblique, margin denticulate, apex acute. Stamens inserted at middle of corolla tube; filaments 7-9 mm; anthers narrowly ellipsoid, 1.5-2 mm. Style 2.5-3 mm; stigma lobes oblong. Capsules sessile, ellipsoid to ovoid-ellipsoid, 1.8-2.2 cm. Seeds light brown, ellipsoid, 1.3-1.5 mm. Fl. and fr. Jun-Aug.
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