Cascara (Rhamnus purshiana) is found in Southern British Columbia, Washington, Oregon, California, Nevada and Idaho. It is a native shrub or small tree that can get to 50 or 60 feet in height, however most specimens are between 10 and 30 feet tall. Its habitat is where deciduous trees such as alder and maple are mixed with conifers.
The bark of cascara is thin, smooth and pale grey. Twigs are brown or reddish and have oval, elevated, horizontal leaf scars.
The barely alternate casara leaves are a glossy dark green with finely, evenly toothed margins. The veins on either side of the midrib are nearly straight and nearly parallel. The veins are set in furrows which can be easily seen on the underside of the leaf. Although cascara is deciduous, young saplings often retain their leaves through the winter.
The small, whitish green cascara flowers are borne in small, branched clusters near the branch tips. Unspectacular, the bell-shaped flowers have five deeply notched petals and produce abundant nectar. There can be up to 25 flowers in a cluster.
Cascara fruits have thin, juicy flesh surrounding 2 or three nutlets, each containing a bright orange seed. The fruits are originally green, maturing to reddish and finally a black color. Although they are edible, the fruits are extremely bitter.
Fresh cascara bark is cathartic and causes acute diarrhea and vomiting. Native Americans used fresh bark to induce vomiting in cases of poison ingestion. Bark that has been heat treated or permitted to dry for two years is a potent laxative and is also used as a “dietary supplement” to treat cancer, gallstones and liver ailments. Cascara bark is harvested commercially and this has resulted in the demise of most large cascara trees. Unfortunately, bark harvesters decorticate the trees, resulting in the death of the tree. However, if the tree is cut down, it will sprout again from the stump and survive. Although cascara was listed in the “approved pharmacopeia” for years, recent concerns about the safety and lack of research concerning its effectiveness as a drug led the FDA to remove cascara preparations from compilations of approved drugs in 2002.
Another common name for cascara is cascara sagrada. Early Franciscan missionaries to California first learned of cascara bark’s medicinal properties from the indigenous people. Sangrada means “holy bark”. Other common names for cascara are chittam bark and buckthorn (cascara is a member of the buckthorn family).
This cascara tree is growing along Burney Creek below Burney Falls in Burney Falls State Park CA. It is a small, shrubby tree. The large tree trunk in the picture is not the cascara, but is another tree behind the cascara.