This native annual plant is 6-18" tall. It forms a low rosette during the fall and bolts during the spring. The central stem is four-sided and stout, sometimes with fine hairs along the ridges. This stem may branch dichotomously in the upper half of the plant. The opposite leaves are up to 3" long and 1" across, oblong in shape, and they usually clasp the stem. Each leaf has a prominent central vein, and a margin that is smooth or with a few coarse teeth toward the base. Usually, there are fine hairs along the margins. The upper stems produce flat-topped clusters of small white flowers. A typical flower cluster will be about ½–¾" across and contain 4-12 flowers, which are surrounded by triangular green bracts. Each flower is about 1/8" across, and consists of a short corolla with 5 small lobes that are without notches at their tips. There are 3 white stamens, and a central stigma with a tripartite style at its tip. The blooming period occurs from mid- to late spring, and lasts about a month. There is little or no floral scent. Each flower is replaced by a ridged 3-chambered fruit that is oval-shaped and longer than it is wide. Only one chamber of the fruit is fertile, which contains a single seed. The root system consists of a slender, branching taproot that is white.