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Portland Nursery

RHAMNUS PURSHIANA: Cascara

Our native of the Buckthorn family, Rhamnus purshiana, is a real “sleeper” among our native trees -- frequently overlooked and underappreciated -- yet it is a widely-adaptable small tree that is a favorite for birds and suitable for the smaller urban garden; growing as a shrub to about 15’, it can also reach 30’ as a small tree.

Described once as looking like “an alder crossed with a birch with a cherry thrown in” -- the Cascara’s mottled gray bark is topped with deeply-ridged, oval leaves usually dark green on their topside with lighter green underneath.

Rhamnus purshiana

Depending on the amount of sun it’s grown in, the fall color can range from yellow to orange - red in the fall. The flowers are small, creamy greenish-white, generally hiding amongst the foliage in small clusters. Butterflies like them, however, and will seek them out. The fruit that follows are small, purple-black beads that attract many species of birds.

Cascara grows in a wide variety of conditions – wet to dry, sun to shade – though it will perform best in a partly sunny, moist site with well-drained soil. That being said, it will happily take summer dry conditions, making it an appropriate site for seasonally wet areas like a rain garden.

Although aphids can sometimes be a pest of Cascara, and its foliage has been noted to be susceptible to Phytophthora, it seems that it tends to be mostly problem-free; and all of its virtues of adaptability, seasons of beauty and attractiveness to birds far outweigh the risks.

 

Rhamnus purshiana

Rhamnus purshiana

FACTS: CASCARA

Family: Rhamnaceae

Genus:  Rhamnus

Common name: Cascara, Cascara Buckthorn

Native Range: British Columbia south to California, primarily west of the Cascades

Characteristics:  Grows as a tall shrub to small tree, 15-30’. Gray bark; oval, large ribbed leaves that are dark green when they emerge, turning yellow to orange-red in fall; small, greenish-yellow flowers followed by purplish-black fruit much loved by birds.

Culture: Takes sun or shade, preferring a mix of both. Prefers moist to wet, well-draining soil; but is also tolerant of summer-dry conditions.

Pests/Diseases: Aphids are sometimes a problem; does not thrive as vigorously in areas of high-pollution. In general, however, Cascara is fairly problem-free.