This annual plant is about 15' tall, branching sparingly in the upper half. The stems are dull green or reddish green, round, and smooth. They have rather conspicuous longitudinal veins and are usually hairless, although occasionally the upper stems and flowering stalks have a few hairs. The alternate leaves are up to 10" long and 3½" across, but more commonly they are about half this size or less. On shorter plants, they are rather crowded together on the stems, even where the composite flowers occur. Depending on the local form of the plant, these leaves may be pinnatifid, or they may lack significant lobes along the margins, in which case they are broadly lanceolate or oblanceolate. The margins are conspicuously prickly, while the base of each leaf is auriculate with a pair of large rounded basal lobes that strongly clasp the stem. The hairless leaves are glabrous, and they tend to be folded upward along the central vein. However, there are no prickles along the central vein on the underside of each leaf. Both the stems and the leaves contain a milky latex. The upper stems terminate in clusters of 1-5 composite flowers on rather short stalks. Each flower is about 2/3" across when fully open, and consists of numerous yellow ray florets. The base of each flower is covered with dull green bracts and is rather short only about 1/3" in length. The blooming period can occur from late spring to early fall, and usually lasts about a month for a colony of plants. Each floret is replaced by an achene with a tuft of silky white hairs. The achenes are flat, spindle-shaped, hairless, and have several longitudinal ribs. They are distributed by the wind. The root system consists of a stout taproot. This plant spreads by reseeding itself.