Bouncing Bet or Soapwort,  Saponaria officinalis
Caryophyllaceae or Pink Family

Plant 1 to 2 feet tall.  Leaves oval, opposite each other, with 3-5 strong ribs.  Flowers white to pink, about an inch across, with bent-back petals notched at the tip.  Flowers are in dense clusters.  Blooms in summer.

Introduced alien weed of roadsides and disturbed places.  In Wildwood occasional along the Riverway.

At first glance, white campion (Silene latifolia) is simmilar, but the leaves have only 1 main veins, the sepalsform an inflated sac, and the petals are deeply cut into two lobes.