From Native Plants PNW:
Pacific Ninebark grows to about 12 feet (4m), sometimes reaching 18 feet (6m) in the wild. It is moderately short-lived. It is found along streams, in wet meadows, coastal marshes and at the edges of moist woods.
 
Pacific Ninebark is most easily recognized by the brown shredding bark on its branches. Its toothed leaves are 3-5 lobed, similar to a maple leaf. At a glance it can easily be confused with salmonberry which has toothed leaves with 3 leaflets. Its flowers are small and white with yellow centers and pink stamens, tightly packed in a hemispherical cluster. Its fruits are small, reddish, inflated follicles (dry one-celled seed capsules or pods, which split open one side). Its flowers are mostly pollinated by native bees but may also be visited by butterflies. Tall arching branches and foliage provide cover.
 
Primary photo credit: John Rusk on Flickr (CC BY 2.0 Deed)
Secondary photo credit: born1945 on Flickr (CC BY 2.0 Deed)