Rhamnus purshiana
Common name: 
Cascara Buckthorn
RAM-nus PURSH-i-an-a
Rhamnus purshianus
Frangula purshiana
Native to (or naturalized in) Oregon: 
  • Deciduous tree to 50 ft (15 m) tall, or an erect shrub 15 ft (4.5 m) tall; twigs soft and velvety pubescent at first; buds naked (without scales), 13 mm long, in 2-3 exposed segments, with rusty pubescence.  Leaves alternate, simple, elliptic to oblong or ovate, 5-15 cm long, flat, round base, abruptly pointed apex, 10-15 conspicuous parallel veins, sparsely serrate or entire, dark green above, lighter below; fall color depending upon sun exposure and varies from pure yellow (shade)to yellow mixed with orange, red, and purple.  Flowers small, green-white, sepals, petals, and stamens in 5s, in clusters.  Fruit 8 mm diameter, purplish-black, sickly sweet taste.
  • Sun or shade.  Best in moist, well-drained soils.
  • Hardy to USDA Zone 3b     Native range from British Columbia south on the west side of the Cascade Mountains to lower California, east through Idaho to western Montana.  The cured bark is used as a mild laxative.
  • purshiana; after Frederick T. Pursh (1774-1820), a German/U.S. botanist, one of the most important early North American plant collectors.
  • Oregon State Univ., Peavy Arboretum, Arboretum Road
Click image to enlarge
  • plant habit, summer and fall

    plant habit, summer and fall

  • flowers, spring

    flowers, spring

  • leaves and immature fuit

    leaves and immature fuit

  • fruit and leaves

    fruit and leaves

  • shoot, leaves, fruit, bud

    shoot, leaves, fruit, bud

  • leaves, fall

    leaves, fall

  • trunk, bark

    trunk, bark

  • twigs and buds, winter

    twigs and buds, winter