This native plant is an annual or biennial from 2-6' tall. Usually, it is unbranched, although sometimes a few side stems will develop from the lower central stem. The central stem is more or less hairy. The alternate leaves are up to 6" long and 2" across, tapering to slender petioles. They are lanceolate to ovate, with serrated margins and a rough upper surface. The central stem terminates in a spike of flowers about ½2' long. From the axils of the upper leaves, secondary spikes of flowers may develop, but these are much shorter (about 16" in length). Each flower is about 1" across, and varies in color from light to dark violet-blue, depending on the local ecotype. The corolla has 5 spreading lobes that are divided nearly to the base; they have a satiny appearance under bright light, and tend to have margins that twist and curl. In the center of the flower is the top of a 5-angled ovary, from which a light violet style is strongly exerted. This style bends downward from the flower, but curls upward near its tip; the small stigma is white and divided into 3 lobes. The flower is often white toward the center, rather than blue-violet. The green tubular calyx is strongly ridged and has 5 long narrow teeth that curl backward when the flower opens. The blooming period occurs from mid-summer to early fall, and lasts about 1½ months. The seed capsule is 5-angled and rather flat-topped. The root system consists of a taproot.