This native perennial wildflower is 3-5' tall. The erect stems are unbranched, except in the upper-third of each plant. Each stem is light green, glabrous, 4-angled, and slightly winged on the angles. The opposite leaves are up to 4" long and 1½" across; they are lanceolate, lanceolate-ovate, or ovate, smooth along the their margins, and glabrous. The upper surface of each leaf is medium green, while the lower surface is pale green. The leaves are sessile or they clasp the stem slightly. The central stem and lateral upper stems (if any) terminate in cymes of 1-5 flowers. Relative to the size of the flowers, branches of each cyme are rather short. Each flower is about 2" across, consisting of 5 yellow petals, 5 green sepals, numerous yellow stamens (about 100), and a light green pistil with 5 persistent styles. The petals are widely spreading and often rather floppy or contorted; they may develop streaks of white with age. The sepals are lanceolate-ovate and much shorter than the petals. The blooming period occurs during mid-summer and lasts about 2-3 weeks. Each flower is replaced by a large hairless seed capsule up to 1¼" long and ½" across. Each seed capsule is divided into 5 cells; each cell contains numerous small seeds that are narrowly oblongoid, flattened, and black at maturity. The root system is rhizomatous, often forming small colonies of plants.