Description from Flora of China
Herbs, perennial. Stems quadrangular. Leaves opposite, basal and rosulate or all on stem. Racemes axillary, opposite, sometimes in compound racemes. Pedicel much longer than flower. Bracteoles absent. Calyx tubular, campanulate in fruit, 5-ribbed; lobes triangular, 1/3-1/2 of tube length, rib reaching lobe apex. Corolla pale purple or pale red; tube long; palate with 2 bulging plaits; limb 2-lipped; lower lip longer than upper, 3-lobed; lobes somewhat spreading, crisp, margin ciliate; lateral lobes of lower lip exserted in bud, as long as lobes of upper lip at anthesis; middle lobe orbicular, larger than other lobes, base with 2 bulging glandular hairy plaits, margin slightly recurved; upper lip erect, lobes 2 and wider than long. Stamens 4, included, didynamous; anther locules basally divaricate, apically confluent. Stigma 2-lobed. Capsule oblong, compressed, emarginate, loculicidal, placenta dilated. Seeds numerous, ellipsoid, compressed, with a transparent membrane.
* Two species: endemic to China.