Spiraea douglasii, commonly known as hardhack, is a shrub of northwestern United States, Canada, and southern Alaska, east to Alberta and Idaho. Large clusters of small pink flowers form spires in early summer, later turning dark and persisting. The leaves are toothed toward the tips. Undersides are whitish with prominent veins. Hardhack grows best in sunny moist places where it forms tall thickets of wiry stems.