Nodding Bur Marigold,  Bidens cernua
Asteraceae or Sunflower Family

Low herb, with sunny flower heads.  Each head has a number of brownish central disc flowers surrounded by about 8 yellow ray flowers about 1/2 inch long (sometimes missing).  Heads face up at first, but bend over and nod as they get older, as a lower right.  Leaves are long, toothed, and opposite each other, and they lack leafstalks.  There is also a whorl of leaf-like bracts behind each flower head.  Blooms in late fall.

This cheerful native lives in wet places.  In Wildwood, found under the tufa near the entrance.

There are many yellow sunflower-like species in the park.  The shortness of this plant, the whorl of leaves behind each flower head, the tendency of old flowers to nod, and the wet habitat are good identifying clues for this species.  If the rays are missing or very small it could be confused with Devil's beggar ticks (B. frondosa), which has no ray flowers, is larger and has leaves divided into 3 to 5 leaflets.

 Flower with bee