Description from Flora of China
Herbs, perennial or annual, terrestrial, not rhizomatous or rhizomatous. Stems branched or simple. Leaves few, along stem, alternate; leaf blade puberulent to glabrous, base sometimes strongly oblique, cuneate to cordate. Inflorescences racemose, lax and later appearing scorpioid, pseudoterminal and/or axillary, few- to many-flowered cymes; bract 1, opposite each flower, alternate [or absent]. Calyx actinomorphic, 5-lobed, sometimes winged; segments equal. Corolla blue to purple, zygomorphic, inside glabrous or sparsely puberulent near mouth; tube tubular to cylindric, not swollen, slightly longer than limb, 1.5-4 mm in diam.; limb 2-lipped; adaxial lip 2-lobed, shorter than abaxial lip; abaxial lip 3-lobed, seldom undivided, lobes equal or subequal, apex rounded and mucronulate or acute to obtuse. Stamens 2 or 4, adnate to corolla tube near middle, if 2 on abaxial side, included; anthers basifixed or dorsifixed, coherent in pairs, thecae nearly parallel or divaricate, confluent at apex, dehiscing longitudinally; connective not projecting; staminodes 2, 3, or absent, adnate to adaxial or adaxial and abaxial sides of corolla tube. Disc cupular. Ovary ovoid, 1-loculed; placentas 2, parietal, projecting inward, 2-cleft. Stigma 1, terminal, subglobose, undivided. Capsule straight in relation to pedicel, ovoid, shorter than calyx, dehiscing loculicidally to base; valves 2, straight, not twisted. Seeds unappendaged.
About 12 species: SE Asia, Pacific Islands; two species in China.