Native Plant of the Month: Cascara
By City Landscape Staff
- Binomial Name: Rhamnus purshiana
- Soil Type: Moist to Dry
- Sunlight: Full Sun to Partial Sun
- Spreads/Multiples: No
- Plant Type: Tall Shrub/Small Tree
- Foliage: Deciduous
- Flowering: Yes
Cascara is native from northern California to British Columbia, as far east as the Rocky Mountains in Montana. It grows in fairly dry to wet sites in full to partial sun and is most common in mixed woods and along stream sides.
Cascara is an erect, tall shrub or small tree about 33ft (10 m) tall, with thin, smooth, silver-grey bark. The shiny, deciduous leaves are simple, alternate and are clustered near the ends of twigs. They are oval (5–15 cm long and 2–5 cm wide), are darker green on top than the bottom, have tiny teeth on the margins, and parallel veins.
Cascara flowers are small (3-4 mm long) and greenish-yellow in color. Its fruits (5-8 mm across) are edible but have a distinctive taste and look like blue-black to purplish-black berries. Cascara’s dried bark has been scientifically verified as an effective laxative, originally used for this purpose in the Pacific Northwest area by Native Americans. It can also be used as a medicine for washing sores, swellings and for internal strains.
Native Plant of the Month is brought to you by the City of Beaverton’s Landscape and Urban Forestry Department.