Cascara Sagrada

Rhamnus purshiana

Physical Characteristics

Rhamnus purshiana is an evergreen Tree growing to 10 m (32ft) by 6 m (19ft). See above for USDA hardiness. It is hardy to UK zone 7. It is in leaf all year, in flower from May to June, and the seeds ripen in October. The species is hermaphrodite (has both male and female organs) and is pollinated by Insects. It is noted for attracting wildlife. Suitable for: light (sandy), medium (loamy) and heavy (clay) soils. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils. It can grow in semi-shade (light woodland) or no shade. It prefers moist soil.

Distribution

Western N. America - British Columbia to California.

Habitats

Edible Uses

Fruit - raw or cooked[2, 118, 161, 257]. A thin, rather juicy flesh[82]. It is sometimes eaten[183]. There is some debate as to whether the fruit is edible or slightly toxic[226]. The fruit is about 10mm in diameter[200] and contains 2 - 3 small seeds[229]. An extract of the bark, with the bitterness removed (by drying?) is a common flavouring for soft drinks, baked goods and ice cream[183].

Medicinal Uses

Cascara sagrada is widely used as a gentle laxative that restores tone to the bowel muscles and thus makes repeated doses unnecessary[226, 244]. It is often sold in chemists etc[226]. The bark is used, this is harvested on a commercial basis from wild trees and plantations in western N. America[226]. 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[95, 213]. Three year old bark is considered to be the best age[4]. It is considered suitable for delicate and elderly persons and is very useful in cases of chronic constipation[4]. The bark also has tonic properties, promoting gastric digestion and appetite[1, 4, 11, 21, 57, 94, 95, 165]. As well as its uses as a laxative, it is taken internally in the treatment of digestive complaints, haemorrhoids, liver problems and jaundice[238]. This remedy should be used with caution since in excess it causes vomiting and diarrhoea[238]. It should not be prescribed for pregnant or lactating women, or patients with intestinal obstruction[238]. 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[238]. The German Commission E Monographs, a therapeutic guide to herbal medicine, approve Rhamnus purshiana for constipation (see [302] for critics of commission E).

Known Hazards

There is the suggestion that this species could be mildly poisonous[19, 65]. 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 [301].