Perennials 60-100 cm tall. Rhizomes blackish, short, with few slightly fleshy rootlets. Stems erect, striate, simple, base sheathed by blackish remains of old petioles. Basal and lower stem leaves alternate; petiole flattened, 8-17 cm; leaf blade oblong to elliptic, 6-13 × 3.5-5.5 cm, base narrowed, apex obtuse, veins 3-5. Middle to upper stem leaves opposite; petiole short, connate, sheathing stem; leaf blade oblong, 5-8 × 2-3 cm, base narrowed, apex obtuse, veins 1-3. Inflorescences dense, many-flowered thyrses. Flowers 5merous. Pedicel 2-3.5 cm. Calyx lobes narrowly lanceolate, 8-10 mm, apex acuminate, veins 3-5. Corolla pale purple to blue-purple, 1.5-2 cm in diam., tube 1.5-2 mm; lobes narrowly ovate-oblong, 1.3-1.6 cm, apex obtuse. Nectaries 2 per corolla lobe, cupular, long fimbriate. Filaments 6-8 mm, base fimbriate-barbate; anthers blue, ellipsoid, 1.5-2 mm. Style indistinct; stigma lobes suborbicular. Capsules ovoid, as long as persistent corolla. Seeds light brown, compressed, suborbicular, 1.5-2 mm in diam., discoid winged. Fl. and fr. Sep.
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