Herbs annual. Stems ca. 50 cm, slender, erect, unbranched, pubescent or retrorse pubescent when young, glabrescent, villous on nodes. Petiole 0.4-2.5 cm, shorter toward stem apex; leaf blade narrowly lanceolate to lanceolate, sometimes slightly curved, 6-12 × 1.2-2.5 cm, papery, puberulent, base rounded to subtruncate, margin sparsely serrulate or undulate-serrulate, apex acuminate. Verticillasters 2-flowered, in upper axils; bracts lanceolate, less than 2.5 cm, margin dentate or subentire. Pedicel 1-4 mm. Calyx tubular, slightly open at mouth, ca. 1.2 cm, puberulent, saccate in fruit; teeth triangular-ovate to subtriangular, ca. 5 mm, apex acuminate, adaxial teeth longer. Corolla red or purple, 2.5-4 cm, pubescent; tube straight or slightly curved, gradually dilated beyond middle; upper lip straight, oblate, apex emarginate; middle lobe of lower lip flabellate, apex emarginate, pilose; lateral lobes oblong, ca. 1/2 as long as middle lobe. Nutlets ovoid-oblong, adaxially slightly triquetrous, densely pubescent, base small umbonate. Fl. May-Jul, fr. Jul-Aug.