Cascara is a small deciduous tree ranging to 10 meters in height with stems to 250 cm in diameter in older trees. On the east side of the Cascades, its form may be more shrub-like. The limbs are relatively few and ascending. The bark is smooth and slightly gray mottled. Older bark may be somewhat scaly near the base of the trunk.
The leaves are typically alternate on the branches, but may occasionally be opposite. The leaves are elliptic to obovate in shape with acute or obtuse apexes. The upper leaf surface is smooth and glabrous while the lower surface is pubescent on each of the 10-15 pairs of prominent, parallel lateral veins. The leaves range from 6-13 cm long with very finely-toothed margins.
The 8-50 small green flowers are umbellate in the leaf axils. The 5 petals are barely longer than the nearly sessile anthers. The short style does not project past the hypantium. The purplish black fruit are widest (8 mm in diameter) at their apex. 2-3 seeds are found in each fruit. The seedy fruits are edible but are mainly useful as survival food.
The drug Cascara Sagrada is made from the bark. This drug has laxative properties.
Cascara is found in moist woods and along streams below 4000'.
Cascara may be found from British Columbia southward along the west side of the Cascade Mts. to northern coastal and Sierran California. It may be found eastward to Idaho and western Montana.
In the Columbia River Gorge, it may be found between the elevations of 100'-4000' from the western approaches to the Gorge east to about Bingen, WA.
The photo above shows a close-up of the leaf of cascara. This leaf shows about 10-11 veins. Some of the leaves of this plant contained 8-9 veins per side of the leaf. Cascara typically has more than 8 lateral veins to the side of the midrib, while R. alnifolia has fewer than 8 per side.