Spiraea densiflora
Common name: 
Mountain Spirea
Pronunciation: 
sp-i-REE-a den-si-FLO-ra
Family: 
Rosaceae
Genus: 
Type: 
Broadleaf
Native to (or naturalized in) Oregon: 
Yes
  • Deciduous shrub, may grow to between 20 and 100 cm (~8 inches to 3+ ft) tall, stems brown, glabrous to finely and sparsely hairy.  Leaves alternate, simple, ovoid, 1–5 cm long, margin toothed near tip and sides but not at the base, leaf surface thin, light green, with or without hairs, turn yellow in fall; petiole less than 3 mm long.  Flowers small (~ 2 mm), rose-pink, in flat-topped, terminal clusters (corymbs), very showy.  Fruit small, 5 valved follicle.
  • Sun to light shade, moist, well-drained soil.
  • Hardy to USDA Zone 3?  Native range from southwestern British Columbia to California, at elevations between 2,000 and 11,000 ft (~600-3,300 m) on inland mountain ranges, especially in moist, rocky areas.
  • Two forms are recognized:
    • Spiraea densiflora subsp. densiflora: more or less hairless (glabrous).
    • Spiraea densiflora subsp. splendens: plants finely pubescent on flower clusters and lower leaf surfaces.  Also named Spiraea splendens.
Click image to enlarge
  • plant habit, start of flowering

    plant habit, start of flowering

  • foliage and flower clusters

    foliage and flower clusters

  • flowering shoots

    flowering shoots

  • flower clusters

    flower clusters

  • leaves

    leaves

  • plant habit after flowering and seed head

    plant habit after flowering and seed head