Eyebane,  Chamaesyce nutans
Euphorbiaceae or Spurge Family
 

Low sprawling herb, up to about 2 feet tall with reddish stems and stalkless oval red-blotched, toothed leaves.  Flower tiny, with what appear to be four white petals (actually glands) and a greenish ball hanging out of them.  Blooms in summer.

Weedy native of dry fields and roadsides.  In Wildwood along the Bikeway, especially near the North Bridge.

Nothing else in the Park resembles it.  Milk purslane (not yet reported in the Park) is a similar plant that is very flat to the ground with smaller leaves.  It is often seen growing from cracks in sidewalks.