Cascara Cascara Buckthorn

Cascara (Frangula purshiana, Rhamnaceae; synonym Rhamnus purshiana) is a native deciduous tree or shrub found from British Columbia south to California and east to western Montana, reaching up to 50 feet as a tree or about 15 feet as a shrub. Alternate, elliptic to oblong leaves (5 to 15 centimeters) have 10 to 15 conspicuous parallel veins. Fall color is pure yellow in shade, mixed with orange, red, and purple in sun. Small green-white flowers yield purplish-black drupes (8 millimeters) with a sickly sweet taste.

Cascara grows in full sun to shade on moist soils (pH 4.5 to 8.5), hardy in Zones 3b to 8b. It is found in rich bottomlands and canyon sides. The cured bark was the principal over-the-counter laxative ingredient in North America until 2002; fresh bark causes severe gastrointestinal distress. Fruit is eaten and dispersed by birds, bears, and raccoons. Documented diseases include leaf spot. No cultivars are in the trade.