Pinnate prairie coneflower, Yellow coneflower (Ratibida pinnata)
 
 

 
 
A member of the Aster (Asteraceae) family, pinnate prairie, or yellow coneflowers are hairy, slender-stemmed branching plants growing to about 4 feet tall.  Leaves are alternate with most being divided into 1 to 4 pairs of narrow lobes with an additional lobe at the tip.  Flower heads are about 3 inches wide on long individual stalks.  Each head contains a brown, bullet shaped central disk less than 1 inch tall and usually taller than wide, surrounded by up to 13 downward-pointing, yellow, petal-like ray flowers. When crushed, seed heads are sharply aromatic.  
Blooming in late spring to fall, this plant is found in mesic to dry prairies, especially in sites with a history of previous disturbance, as well as in open thickets and along banks.

 

Additional information about this plant may be found at the USDA PLANTS Database:

http://plants.usda.gov/java/nameSearch?keywordquery=Ratibida+pinnata