ANNUAL SUNFLOWER--Helianthus annuus
Description:  This annual, taprooted forb normally reaches heights of 2 to 8+ feet.  The entire plant is rough with stiff, sharp hairs or bristles.  Heads produced in July through September have 17 or more rays about 1 inch long.  Bracts of the involucre are broad, fringed with bristly hair, and abruptly tapered to a slender tip.  Leaf blades are broad, ovate or almost triangular; often longer than 4 inches.
Distribution, habitat:  Annual sunflower is native throughout North and Central America, including all of the Great Plains.  It is frequently in great abundance in fields of cultivated crops, on go-back land, along roadsides, in deteriorated rangelands, and in disturbed areas.
Comments:  Plains sunflower, H. petiolaris, resembles annual sunflower but is shorter, mostly less than 4 feet.  It prefers sandy soils and is less common than annual sunflower.  It also differs in that there are whitish hairs in the center of the disk and the bracts of the involucre are narrower, tapered (not abruptly) to the tip, and not conspicuously edged with bristly hair.  Leaf blades are smaller, narrower, and less than 4 inches long.  Annual and plains sunflowers hybridize, creating intergrades where both exist.
As forages, annual sunflowers are highly palatable early in the season, with reduced palatability as they mature.  Livestock and wildlife readily graze the flower heads.  Birds relish their seeds.  American Indians extracted oil from seeds for hair dressing and for cooking.  Meal from crushed seed was used for making bread or thickening soups.  Commercial varieties of sunflower provide cooking oils, meal for livestock, and seeds for confectionary use.  Annual sunflower is the state flower of Kansas.
Picture and information can be found on pages 120 and 121 of Grassland Plants of South Dakota and the Northern Great Plains, by James R. Johnson and Gary E. Larson.  Published in 1999 by South Dakota State University, Brookings, SD.