Cascara Cascara Buckthorn

Cascara, sometimes listed under its older name Rhamnus purshiana, now classified as Frangula purshiana, is the native deciduous tree of lowland forests and riparian corridors throughout Western Washington. You walk past it constantly in second-growth woods without knowing it. It grows to about fifty feet with an upright, often multi-stemmed form, and the bark is smooth, thin, and historically significant: cascara sagrada was once a major commercial laxative product harvested from Pacific Northwest forests. Small green-white flowers appear in spring, and the fall color is genuinely exceptional, orange, purple, red, and yellow.

Cascara grows in sun to full shade and tolerates the heavy, moist soils of lowland bottomlands and the drier conditions of upland forest edges equally well. One disease is tracked with no significant pest pressure. In managed landscapes, cascara works as a naturalized woodland tree, a screening plant, or a native shade tree where indigenous species are the design priority. The multi-season interest, spring flowers, summer foliage, exceptional fall color, and the smooth bark that catches winter light, makes it far more ornamental than its obscurity suggests. If you are building a native plant palette for a residential or restoration project, cascara fills the medium-tree niche with distinction.