Trees deciduous. Leaves simple, purple glandular punctate at vein axils abaxially. Inflorescences paniculate, corymbose, or racemose, terminal. Calyx bilabiate or irregularly divided, globose in buds. Corolla campanulate, bilabiate, upper lip 2-lobed, lower lip 3-lobed. Fertile stamens 2, included, inserted at base of corolla tube; staminodes 3. Disc conspicuous. Ovary 2-locular; ovules several. Capsule dehiscing loculicidally, long terete; valves thin; septum slender, terete. Seeds in several rows, rounded, thin membranous, with hair tufts at both ends.
"Cal splitting irregularly or more commonly into 2 unequal lobes; cor large, evidently bilabiate, with an oblique, campanulate tube and 5 spreading lobes erose or crisped on the margin; stamens commonly 2, about as long as the cor-tube, accompanied by 3 minute staminodia, or occasionally 4 with 1 staminodium; fr elongate, cylindric, bilocular, loculicidal; seeds flat, narrowly oblong, the 2 wings terminating in hairs; trees with opposite or whorled, simple, cordate-ovate to rotund, entire or shallowly lobed lvs and terminal panicles of large, white or yellowish fls ± spotted or mottled with yellow and purple. 10+, e. N. Amer. and e. Asia."