Plant Data Sheet




Species (common name, Latin name)

Cascara buckthorn, Rhamnus purshiana



From southern B.C. to western Montana and down to central California (Rose)


Climate, elevation

Generally a moist –site indicator, 0 to 900m (Tirmenstein) (Rose)


Local occurrence (where, how common)

Southern Puget Sound region down to southern Washington (Pojar)


Habitat preferences

Canyons, bottomlands, and lower mountain slopes, Prefers moist, well drained soils and quite tolerant of shade (Rose) (Leigh)


Plant strategy type/successional stage (stress-tolerator, competitor, weedy/colonizer, seral, late successional)

Long lived invader species (Tirmenstein)


Associated species

Abies concolor, Tsuga heteophylla, Pseudotsuga menziesii, Acer spp., Gultheria shallon, Berberis spp., Rubus nivalis (Tirmenstein)


May be collected as: (seed, layered, divisions, etc.)

Seed and vegetative (Rose)


Collection restrictions or guidelines

Fruit ripens from July through September. Collect fruit two weeks before it fully ripens, Separate seed by macerating with water and floating off pulp. Hardwood cuttings can be taken in September and October (Rose)


Seed germination (needs dormancy breaking?)

Cold stratify at 1-5 ˚C for 90-115 days if planted in spring (Rose)


Recommended seed storage conditions

Store in sealed containers at 5˚C; longevity unknown (Rose)


Propagation recommendations (plant seeds, vegetative parts, cuttings, etc.)

Sow seed outdoors in fall; layering can be done in the early spring (Rose)


Soil or medium requirements (inoculum necessary?)

Moist soil (Tirmenstein)


Installation form (form, potential for successful outcomes, cost)

Nursery grown seedlings work best. Seedlings under four feet tall may be salvaged (Leigh)


Recommended planting density

Sow 2.5 cm deep with shading. Minimum density per acre=300; maximum density per acre=700 (Rose) (Vegspec)


Care requirements after installed (water weekly, water once etc.)

Plant in full shade and in moist soil conditions; supplemental watering may be required (Tirmenstein)


Normal rate of growth or spread; lifespan

Slow rate of growth, mature height=35 ft (Vegspec)


Sources cited


Leigh, Michael. Grow Your Own Native Landscape. Native Plant Salvage Project, WSU Cooperative Extension-Thurston County. Revised ed. June 1999.


Pojar, Jim and Andy MacKinnon. Plants of the Pacific Northwest Coast-Washington, Oregon, British Columbia and Alaska. B.C. Minisrty of Forest and Lone Pine Publishing. 1994.


Rose, Robin, Caryn Chachulski, and Diane Haase. Propagation of Pacific Norhtwest Native Plants. Oregon State University Press, Corvallis, OR. 1998.


Tirmenstein, D. 1991. Rhamnus pursiana. In: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (2003, May). Fire Effects Information System, [Online]. Available: May 14, 2003.


VegSpec. Phil Smith, Project Manager., USDA, Natural Resource Conservation Service. May 14, 2003.


Data compiled by (student name and date)

Scott Olmsted; 051403