Oxeye or False Sunflower (Heliopsis helianthoides)

Asteraceae or Sunflower Family
 

Two to five feet tall.  Leaves long-stalked, coarsely toothed and all in pairs opposite each other.  Flower heads about 2 in wide.  Disk flowers in center orange to yellow.  Ray flowers ("petals") yellow, strongly wrinkled.  The ray flowers are fertile; with a hand lens, a tiny forked pistil is visible at the base, as in the picture at right.

Plant of open woods, occasional along Riverway bikepath in Wildwood.  Blooms in late summer.

There are a number of yellow sunflower-like plants in the Park.  The leaf shape, the leaf teeth, and the fact that all leaves are opposite is a good indication you have found this plant.  A clincher is to examine the ray flowers with a hand lens and look for the pistil at the base; true sunflowers do not have fertile rays.