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Buckthorn Purshs

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  • Botanical: Rhamnus purshiana
  • Family: Rhamnaceae
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Buckthorn Purshs


Rhamnus purshiana



Known as

cascara buckthorn, cascara, bearberry,

Old Use

medical, culinary, industry

Parts Used

bark, fruit


abdominal pain, constipation, gastrointestinal, jaundice

Heart & Circulation


Stomach & Intestinal

abdominal pain, constipation, digestion, gastrointestinal, laxative, liver weakness, indigestion


antispasmodic, stomachic


Cascara is a large shrub or small tree 4.5–10 m tall, with a trunk 20–50 cm in diameter. The outer bark is brownish to silver-grey with light splotching (often, in part, from lichens) and the inner surface of the bark is smooth and yellowish (turning dark brown with age and/or exposure to sunlight). Cascara bark has an intensely bitter flavor that will remain in the mouth for hours, overpowering the taste buds. The leaves are simple, deciduous, alternate, clustered near the ends of twigs. They are oval, 5–15 cm long and 2–5 cm broad with a 0.6–2 cm petiole, shiny and green on top, and a dull, paler green below; and have tiny teeth on the margins, and parallel veins. Leaves, flower, and young fruits of R. purshiana The flowers are tiny, 4–5 mm diameter, with five greenish yellow petals, forming a cup shape. The flowers bloom in umbel-shaped clusters, on the ends of distinctive peduncles that are attached to the leaf axils. The flowering season is brief, from early to mid- spring, disappearing by early summer. The fruit is a drupe 6–10 mm 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

Properties & Uses

Cascara sagrada is widely used as a gentle laxative that restores tone to the bowel muscles and thus makes repeated doses unnecessary. It is often sold in chemists etc. The bark is used, this is harvested on a commercial basis from wild trees and plantations in western N. America. It should be harvested in the autumn or spring at least 12 months before it is used medicinally, in order to allow the more violent purgative effect to be mollified with age. Three year old bark is considered to be the best age. It is considered suitable for delicate and elderly persons and is very useful in cases of chronic constipation. The bark also has tonic properties, promoting gastric digestion and appetite. As well as its uses as a laxative, it is taken internally in the treatment of digestive complaints, haemorrhoids, liver problems and jaundice. This remedy should be used with caution since in excess it causes vomiting and diarrhoea. It should not be prescribed for pregnant or lactating women, or patients with intestinal obstruction. An infusion of the bark is sometimes painted over finger nails in the hope that the bitter taste will deter the person from biting their nails

Other Uses

A green dye is obtained from the bark. Plants are sometimes grown in America as an ornamental hedge. Wood - light, soft, not strong. Used for making the handles of small tools.

Fruit - raw or cooked. A thin, rather juicy flesh. It is sometimes eaten. There is some debate as to whether the fruit is edible or slightly toxic. The fruit is about 10mm in diameter and contains 2 - 3 small seeds. An extract of the bark, with the bitterness removed is a common flavouring for soft drinks, baked goods and ice cream


There is the suggestion that this species could be mildly poisonous. Excessive use can cause cramps and diarrhoea. Limit treatment to 8-10 days. Long term use can be habit forming. Fresh cascara can cause a bloody diarrhoea and vomiting. It should be aged for at least 1 year or heat treated. Do not use on children


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.


Numerous quinoid substances are found in the bark of cascara. The chemicals primarily responsible for the laxative action are the hydroxyanthracene glycosides, which includes cascarosides A, B, C, and D. Cascara contains approximately 8% anthranoids by mass, of which about two-thirds are cascarosides. The hydroxyanthracene glycosides act as a stimulant laxative by exciting peristalsis in the colon. They trigger peristalsis by inhibiting the absorption of water and electrolytes in the large intestine, which increases the volume of the bowel's contents, leading to increased pressure. The hydroxyanthracene glycosides are not readily absorbed in the small intestine but are hydrolyzed by intestinal flora to a form that is partly absorbed in the colon. Hydrolysis of the cascarosides results in the formation of aloins such as barbaloin and chrysaloin. Some of the chemical constituents present in the bark may be excreted by the kidney following medicinal use, resulting in a harmless change in the color of the urine. Studies have shown that the extract from cascara bark also contains a substance called emodin, which may have anti-cancer effects. Emodin is also responsible for some of the laxative effect, due to its excitation of smooth muscle cells in the large intestine.

For educational purposes only This information has not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure, or prevent any disease.