Rhamnus purshianus
Common Name: Cascara Sagrada.
Family: Rhamnaceae.
Known Hazards: There is the suggestion that this species could be mildly poisonous.
Habitats: Rich bottom lands and sides of canyons, usually in coniferous forests.
Range: Western N. America - British Columbia to California.
Physical Characteristics
Rhamnus purshianus is an evergreen Tree growing to 10 m (32ft) by 6 m (19ft). It is hardy to zone 7. It is in leaf 12-Jan It is in flower from May to June, and the seeds ripen in October. The flowers are hermaphrodite (have both male and female organs) and are pollinated by insects. It is noted for attracting wildlife.
The plant prefers light (sandy), medium (loamy) and heavy (clay) soils. The plant prefers acid, neutral and basic (alkaline) soils. It can grow in semi-shade (light woodland) or no shade. It requires moist soil.
Edible Uses
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 (by drying?) is a common flavouring for soft drinks, baked goods and ice cream.
Medicinal Uses
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Medicinal Actions: Laxative; Purgative; Tonic.
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.
Cultivation
Succeeds in any reasonably good soil in sun or partial shade. This species is hardy to at least -15°c. Closely related to R. frangula. This species is cultivated as a medicinal plant in N. America and is also collected from the wild. It is becoming rare in the wild because of over-collection. The flowers are produced in small clusters on shoots of the current year’s growth. A good bee plant. The species in this genus are notably resistant to honey fungus.
Propagation
Seed - best sown in the autumn in a cold frame. Stored seed will require 1 - 2 months cold stratification at about 5° and should be sown as early in the year as possible in a cold frame or outdoor seedbed. Prick out the seedlings into individual pots when they are large enough to handle, and grow them on in the greenhouse or cold frame for their first winter. Plant them out in late spring or early summer of the following year. Cuttings of half-ripe wood, July/August in a frame. Cuttings of mature wood of the current year’s growth, autumn in a frame. Layering in early spring.
