Perennial with creeping underground stems; aerial parts densely scabrid with many hairs bulbous-based; aerial stems spreading towards base, then ascending to c. 1 m tall, square. Lvs sessile, 3-10 × 1-2 cm; basal lvs often obovate; stem lvs narrow-elliptic or elliptic-oblong, sharply dentate or serrate; veins impressed; base ± amplexicaul except in basal lvs; apex acute. Infl. with several branches, densely hairy; spikes mostly 1.5-2.5 cm long at maximum flowering, elongating to 5 cm long at fruiting, stout; fls dense. Bracts 6-10 mm long, narrow-lanceolate to lanceolate, subulate, rigidly ciliate, somewhat glandular, purple, prominently keeled, well-exserted beyond calyx. Calyx 4-5 mm long; teeth subulate, glandular-hairy, purple. Corolla purple, sometimes drying deep blue; tube 2-3× length of calyx, hairy outside; limb 5-7 mm diam. Nutlets 1.5-2 mm long, oblong, ± light brown, longitudinally ribbed dorsally, white-papillate on flattened ventral surface.