Frangula purshiana

Species of buckhorn shrub

Frangula purshiana (cascara, cascara buckthorn, cascara sagrada, bearberry, and in the Chinook Jargon, chittem stick and chitticum stick; syn. Rhamnus purshiana) is a species of plant in the family Rhamnaceae. It is native to western North America from southern British Columbia south to central California, and eastward to northwestern Montana. The dried bark of cascara was used as a laxative in folk medicine by the indigenous peoples of the Pacific Northwest, and later worldwide in conventional medicines until 2002.

Cascara is a large shrub or small tree tall, The buds have no scales, unique for the northwest region. Cascara bark has an intensely bitter flavor that will remain in the mouth for hours, overpowering and even numbing the taste buds. they have tiny teeth on the margins, and 10–12 pairs of pinnate veins. The leaves turn yellow in autumn. The fruit is a drupe diameter, bright red at first, quickly maturing deep purple or black, and containing a yellow pulp, and two or three hard, smooth, olive green or black seeds.

Cascara is native from northern California to British Columbia and east to the Rocky Mountains in Montana. It is often found along streamsides in the mixed deciduous coniferous forests of valleys, and in moist montane forests. Cascara is common in the understory of bigleaf maple forest, alongside red osier dogwood and red alder. In many areas, the high market demand for cascara bark has led to over harvesting from wild trees, which may have heavily reduced cascara populations. and other mammals, who distribute the undigestible seeds. as well as ring tailed cats where their range overlaps with Cascara in Northern California. Cascara is shade tolerant. Serious adverse effects may occur from using cascara, including dehydration, loss of electrolyte levels (such as potassium, sodium, chloride), heart rhythm irregularities, and muscle weakness. Use of cascara is a safety concern for pregnant or breastfeeding women, and for children. The hydroxyanthracene glycosides may trigger peristalsis by inhibiting the absorption of water and electrolytes in the large intestine, which increases the volume of the bowel contents, leading to increased pressure. The extract from cascara bark also contains emodin, which may contribute to the laxative effect.

Cascara was used in traditional medicine as a laxative. Commercially, it is called "cascara sagrada" ('sacred bark' in Spanish), while in the traditional Chinook Jargon it is known as "chittem bark" or "chitticum bark".

The bark is collected in the spring or early summer, when it easily peels from the tree. Once stripped from the tree, the bark must be aged for several months, because fresh cut, dried bark causes vomiting and violent diarrhea. This drying is generally done in the shade to preserve its characteristic yellow color. This process can be quickened by simply baking the bark at a low temperature for several hours. J. A. Duke suggests an effective dosage is approximately dried bark, or powdered bark.

The fruit can also be eaten cooked or raw, but has a laxative effect. The food industry sometimes uses cascara as a flavoring agent for liquors, soft drinks, ice cream, and baked goods.