From Native Plants PNW:
Mountain Huckleberry has thin leaves with finely toothed margins that are pointed at the tip. Flowers are urn-shaped and creamy-pink. The berries are purplish or reddish-black, without a waxy bloom.
 
This species is prized for its delicious berries.  Its leaves turn a spectacular red to purple in the fall. Mountain Huckleberry does best when it has little competition from other plants and is ideal for a rock garden or on a slope with plenty of organic matter.  Plant it together with its natural companion, Beargrass, to reproduce the look of a subalpine hillside.  Soil moisture will affect the quality and quantity of berry production, although it still will fruit even after 4-6 months with no rain.
 
Bloom time:  Late spring to June. Fruit ripens: Mid-summer to late August.
 
Primary photo: Katja Shulz on Flickr (CC BY 2.0 Deed)