This native annual has an erect, stout stem from 2 to more than 10 feet tall. Rough, coarsely hairy, heart-shaped leaves up to 16 inches long and 8 inches wide are usually alternate, although they may be opposite at the base of the stem (B). The 3-6 inch flower heads come off the spreading upper branches. The yellow, petal-like ray florets, 1 inch or more in length, surround the fertile, seed-producing reddish to purple central disk florets (A). Of all our sunflowers with a flat central disk (“flatheads”), only the annual sunflower has both broad, often heart-shaped leaves and a dark central disk.
Found on disturbed sites, especially fields and roadsides, flowering from July through September. At Neale Woods, it is uncommon in the Nebraska and Jonas Prairie restorations.
Sunflowers were first cultivated by Native Americans, who over centuries gradually changed the genetic composition by selecting plants with the largest seeds. Wild plants are the ancestors of the many forms of common sunflower now cultivated worldwide.
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