A very hairy, tall, much-branching perennial, often occurring in dense colonies. Flowerheads sunflowers, with 12–20 ray florets, to 3 inches across, frequently with a distinct chocolate scent. Blooms August–October. Leaves with winged petioles, lance-shaped, coarsely toothed, to 9 inches long, prominently 3-veined, rough and hairy above, downy below. Roots potato-like, edible tubers.
Similar species: This species hybridizes with other sunflowers, making identification difficult. Not counting hybrids, there are 16 species of Helianthus recorded for Missouri. This species is perhaps best identified by its leaves, which are mostly opposite, but alternate in the upper third of the plant; also that the leaves are long, lanceolate, 3-veined, coarsely toothed, long-tapered at the base with winged petioles, and rough-hairy above, downy below.