Erect herb, 7-90 cm tall, +/- glabrous, unbranched or with few, strongly ascending branches mostly from near apex. Leaves opposite, sessile; blades mostly ovate, acute to short-acuminate at apex, attenuate to amplexicaul at base, 1.5-8 (10) cm long, 0.5-4 (4.5) cm wide, thin. Inflorescences terminal or upper-axillary, simple or compound dichasia, bearing few flowers; pedicels 1-10 mm long, subtended by bracts, the bracts paired, narrowly ovate, persistent, to 1.5 (2) cm long; flowers 4-parted, lavender, 1-1.7 cm long; calyx lobed to near base, ca 6 mm long, the lobes +/- lanceolate, strongly keeled; calyx and corolla withering but persisting at apex of fruit; corolla funnelform, shallowly 4-lobed, 1-1.7 cm long; stamens 4-5 mm long; style simple, 2-3 mm long. Capsules fusiform, 6-9 mm long, 2-3 mm diam; valves 2, thick, held together at apex by withered corolla; seeds minute, irregularly rounded. Croat 7783.