This native perennial plant is about 3-6' tall, branching occasionally. The stems are often 4-angled or furrowed; they are slightly hairy while young, but become glabrous with age. The opposite leaves are up to 8" long and 3" across (excluding the petioles), becoming somewhat smaller as they ascend the stems. They are cordate-ovate to ovate, serrated along the margins, thin-textured, and largely hairless. The petioles are long and slender; each petiole is at least one-fourth the length of the leaf blade. The upper stems terminate in an inflorescence consisting of pairs of cymes up to 2' tall. This inflorescence is somewhat cylindrical. There is usually a pair of slender bracts at the base of each pair of cymes. Each flower is about ¼" long and has a short cylindrical shape. The exterior of the tubular corolla is dull green, while its interior is predominantly reddish brown. This corolla has a divided upper lobe that functions as a hood, 2 short side lobes, and a lower lobe that curves downward. All of these lobes are reddish brown on the inside, except the lower lobe, which is green or yellow. Appressed against the upper interior of this corolla, there is an infertile stamen that is reddish brown or purple. The fertile stamens have yellow anthers; they are located toward the bottom of the corolla. The tubular calyx is green and shorter than the corolla; it has 5 blunt teeth. The slender pedicels are longer than the flowers. The blooming period occurs from mid-summer to early fall and lasts about a month; only a few flowers are in bloom at the same time. Each flower is replaced by a globular capsule that contains several seeds. The root system consists of a taproot.