Herbs perennial, rhizomatous. Stems 1-2 m, pubescent, sometimes also spreading minutely hispid. Petiole 2-10 cm; leaf blade cordate to oblong-ovate, 5-16.5(-18) × 3-14 cm, papery, finely strigose, abaxially sometimes also spreading minutely hispid on veins, base truncate-cuneate to cordate, margin mucronate crenate-serrate, apex short caudate-acuminate. Cymes dichotomous, many flowered, axillary or in terminal panicles ca. 2-3 × 3-4 cm; peduncle 1.5-6 cm; bracts lanceolate to linear, 6-10 mm. Calyx ca. 6.5 × 3 mm, puberulent, sparsely minutely hispid; teeth narrowly oblong to lanceolate, 1.5-2 mm, apex obtuse to acuminate, posterior tooth ca. 3 mm; fruiting calyx saccate-dilated, netted. Corolla yellow, sometimes tinged red or purple-red on upper lip, ca. 1.5-2.6 cm, throat to 5.5 mm wide; upper lip ca. 6.5 mm, back rounded, base subtruncate; lower lip as long as upper, lobes circular, middle lobe largest. Nutlets black-brown, flattened, triquetrous, globose, ca. 2 mm in diam. Fl. Aug, fr. Sep-Oct.
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