Description from Flora of China
Plants rhizomatous perennial, herbs or subshrubs. Stems usually unbranched, erect. Leaves petiolate or subsessile, dentate. Verticillasters 6-10-flowered, in long, terminal, densely white stellate tomentose spikes; bracts leaflike or scalelike, early deciduous; bracteoles indistinct, minute. Calyx tubular-campanulate, inconspicuously 10-veined, stellate tomentose outside, glabrous inside; teeth 5, short triangular, apex acute, anterior 2 longer. Corolla reddish to purple, 2-lipped; tube funnelform, villous annulate near middle; upper lip 2-lobed or occasionally entire; lower lip 3-lobed, middle lobe ovate, spreading, concave, ± saccate; lateral lobes erect, smaller than middle lobe. Stamens 4, anterior 2 longer, much exserted; filaments glabrous; anthers ovoid, cells 1, transversely dehiscent. Ovary brown, glabrous, glandular. Nutlets triquetrous, ellipsoid, yellow-brown, golden glandular.
About six species: China, Japan; three species in China.