This native perennial plant is 1-3' tall, branching frequently to create a bushy appearance. The stems are hairless and 4-angled, but not conspicuously winged. The opposite leaves are up to 4" long and 1" across. They are lanceolate or oblong-lanceolate, hairless, and serrated along the margins. The base of a leaf is either sessile or somewhat eared (auriculate); if the latter, it clasps the stem. Individual flowers develop from the leaf axils of the upper stems. These flowers are about 1" long, and have two-lipped corollas that are usually blue-violet (less often, pink or white). The upper lip of the corolla has 2 erect lobes, while the lower lip has 3 rounded lobes. The inner surface of the lower lip often has 2 small ridges. The throat of the corolla has a patch of yellow and is barely open because of an abundance of fuzzy hairs. The tubular calyx is green and has 5 long teeth that taper gradually to a point. The blooming period occurs from mid- to late summer and lasts about 1–1½ months. There is no floral scent. Each flower is replaced by a rounded seed capsule that contains numerous tiny seeds with a reticulated surface. The seeds are dispersed by wind or water. The root system consists of a taproot and rhizomes. This plant can spread vegetatively, but it isn't a strong colonizer.