Perennial herb; stems gray-green, glabrous, up to 70 cm tall, branching from the base; leaves opposite, entire, slightly thickened, basal leaves short petiolate, ovate to elliptic, to 12 cm long, stem leaves smaller, sessile, ovate to lanceolate; flowers mostly concentrated along one side of the stem; calyx 3-5 mm long, lobes ovate, acute or obtuse, thinnest near the margins; corolla red, 22-30 mm long, narrowed at the mouth, lower lobes bearded with soft yellow hairs; sterile stamen bearded near the tip. Flowers June and July.