Herbs, up to 90 cm tall, stems 10–20 cm. Leaves opposite, clustered at stem apex; petiole 5–8 (–15) cm long and winged, wings (1–) 5–20 mm wide each side; leaf blade obovate, 12–30 (–48) × 5–13 (–16) cm, chartaceous, adaxially sparsely pubescent to glabrous, abaxially densely matted arachnoid, base cuneate to wing-like on petiole, margin repand-crenate and involute, apex mucronate to rounded; midrib depressed adaxially, protuberant abaxially; lateral veins 8–13 (–16) pairs, obscure adaxially and distinct abaxially. Dichasium terminal paniculate, with hundreds of flowers; peduncles up to 70 cm, densely arachnoid when young, sparsely puberulent to glabrous when mature; bracts (the lowermost fertile leaves) 2, leaf-like, ca. 7 × 3 cm, densely arachnoid abaxially; bracteoles 2, linear, ca. 2 × 0.5 mm; pedicels 5–8 mm long. Calyx 5-sect from base; segments linear, ca. 1 mm long, glabrous. Corolla purple adaxially and white abaxially (corollas purple when young), outside glandular-puberulent; tube obliquely campanulate, ca. 10 mm long, outside glandular-puberulent; adaxial lip 2-lobed, lobes semicordate ca. 3 × 6 mm; abaxial lip 3-lobed, lobes ca. 5× 6 mm. Stamens 2, included; filaments lateral-fixed, ca. 8 mm long, glandular-puberulent from middle to top; anthers ca. 5 mm long; staminodes 2, 3–5 mm long. Pistil glabrous; ovary oblong, ca. 6 mm long; style linear, 4–5 mm long; stigma capitate. Capsule obviously twisted, 4.5–6.7 cm long, glabrous, with persistent calyx. Seeds ellipsoid, 0.6–0.7 × 0.15–0.2 mm.
