Rhizomes with robust, fibrous roots. Stems erect or ascending, 24-50 cm, sparsely pubescent basally, densely retrorse pubescent at apex, with 2-4 nodes below dense spikes. Petiole of basal leaves 4.5-9(-22.5) cm, that of cauline leaves as long as blade to sometimes absent; leaf blade ovate to broadly ovate, 2-5.5(-7) × 1.5-4.2(-7) cm, adaxially sparsely pubescent or glabrous, abaxially densely pubescent or occasionally glabrous throughout, base cordate, apex rounded to obtuse. Verticillasters in terminal capitula or interrupted spikes 3-3.5 cm; floral leaves sessile, ovate; bracts green-purple, purple-black veined, rhombic-obovate to oblate, as long as calyx, margin acute or short spinescent to 3-6-serrate, veins and margin densely villous. Calyx 1.4-1.7 cm, conspicuously purple veined at base, tinged purple black at apex, villous, ciliate, 2-lipped 1/3-1/2 its length; upper lip middle tooth obovate to ovate, slightly wider to 2 × as wide as lateral teeth, margin entire to serrulate, apex short acuminate; lateral teeth of upper lip ovate-triangular, apex acute; lower lip teeth lanceolate. Corolla dark purple, 2-3 cm, pubescent, tube 3-6 mm wide; upper lip navicular, ca. 5 mm; lower lip spreading, with dark spots, 3-lobed; middle lobe of lower lip obovate, apex emarginate. Nutlets dark brown, elliptic-obovoid, flattened, ca. 3.5 mm. Fl. Jul-Sep.