Shrub or undershrub, 1–3 m. high. Branchlets quadrangular or approximately so, rusty–pubescent with stellate and/or glandular hairs, less often almost glabrous. Leaves opposite or subopposite, very variable in shape and size, shortly petiolate; stellate–pubescent, 1–7 mm. long; lamina sparsely pubescent to glabrous above, minutely to densely pubescent with often stellate hairs beneath, membranaceous when dry, ovate, elliptic, or narrowly elliptic, 2–3(–5) times as long as wide, 2–11 x 0·7–5 cm. or sometimes smaller, long–acuminate at the apex, cuneate at the base, entire to coarsely sinuate–dentate; secondary veins conspicuous. Inflorescence terminal, almost spicate, more or less interrupted, 4–20 x 2–4 cm. Flowers shortly pedicellate. Calyx campanulate or urceolate, 2–3·5 mm. long, outside densely pubescent with glandular and often also some stellate hairs; tube 3–10 x as long as the lobes; lobes often dentate, subequal or unequal, mostly broadly triangular, 0·2–1 x 0·5–1 mm. Corolla purple, usually curved, with erect lobes 4–10 times as long as the calyx, 13–20 mm. long, pubescent with glandular and often also some stellate hairs outside; tube nearly cylindrical, gradually widened from somewhat above the insertion of the stamens, 3·5–8 times as long as the calyx, 5–6 times as long as the lobes, 11–17 mm. long, lobes suborbicular, about as long as wide or wider, 2–3 mm. long, stamens included; filaments inserted 3–6 mm. above the base of the corolla.
