Cascara Buckthorn - Rhamnales Rhamnaceae Rhamnus purshiana
Identification & Description:
The cascara tree is usually from 15 to 20 feet in height. The rather thin leaves are from 2 to 6 inches long and about 1 to 3 inches wide, somewhat hairy on the lower surface and rather prominently veined. The small, insignificant greenish flowers are produced in clusters and are followed by black, 3-seeded berries of a somewhat insipid taste. The bark is gray or brown, thin and fissured into short, thin scales AND has a somewhat aromatic odor and an extremely bitter taste. In the cascara district several other species of Rhamnus occur which are not commercially important, but their resemblance to R. purshiana may lead inexperienced persons to include the bark of such species in their collections. The red berry- like fruit turns purplish- black in autumn.
Buckthorn, common name for a family comprising about 875 species, in 53 genera, of mostly trees and shrubs, although some are climbers. The family is cosmopolitan in distribution. Many species exhibit adaptations to dry habitats, including small, crowded leaves; thorns and spines; and short branches. In addition to ornamentals, the family is important as a source of some medicines (see Cascara Sagrada). It is also an important source of natural green and yellow dyes and fruits (from the lotus tree, or jujube). The common buckthorn, sometimes cultivated in shrub borders, has large spines; small, oval leaves; and small white flower clusters. Its blue-black, pea-size berries are cathartic.
The family belongs to an order that contains two other families. The distinctive feature of the order is the nature of the flowers, which always have as many stamens (male flower parts) as petals, usually four or five. Also, whereas in most plant groups the stamens are attached between the petals, in this order they are attached opposite the petals. Another distinctive feature of the flower is a disk of nectar-producing tissue located between the stamen and the pistil (female flower part).
One of the other families in the order contains about 13 genera and 700 species of mostly tropical and subtropical climbers with tendrils (modified shoots) that coil around objects, attaching the vines to them. This family is of tremendous importance because it contains the genus from which wine, grapes, and dried fruits are obtained. Virginia creeper, or American ivy, an attractive ornamental, is also a member of this family (see Ivy). The third family contains about 70 species, all placed in one genus.
Scientific classification: Buckthorns make up the family Rhamnaceae, of the order Rhamnales. The common buckthorn is classified as Rhamnus cathartica. Two other families of the order are Vitaceae, containing the genera Vitis and Parthenocissus, and Leeaceae, containing the genus Leea.
Once protected by law in British Columbia because it was harvested in such huge numbers and in danger of becoming extinct, the law was removed because the chemical found in the bark can now be made chemically. Today, other chemicals, such as Sennosides, are more commonly used as laxatives.
The Cascara prefers rich, well-drained soils in areas where it gets moisture all summer (usually low elevations). It can be found all along the BC coast & on islands south to Nothern California as well as inland in the Columbia Valley. Look for it near streams.
Early in the spring, the buds and new leaves have a coppery tone to them.
Leaves grow to about 15 cm long and have strong parallel veins on them which gives them a rippled effect up close. Leaves grow in groups at ends of the branches. The leaves have finely toothed edges and are paler below.
Its tiny greenish flower clusters appear in May and grow into clusters of finger-nail sized green, then red, then purplish shiny berries by September which provide fall and winter food for robins, other thrushes, waxwings and squirrels. The seeds get dispersed to new areas when they pass through the birds' digestive systems.
Bark is mottled greyish and smooth. Adult trees have a scaley base. First Nations people and later pioneers collected the bark of this tree in spring, dried it for about a year, ground the bark into a powder and used it as a laxative.The laxative was given the name Cascara Sagrada which means "sacred bark", by Catholic Priests.
Under the bark of every tree is a thin layer called the cambium layer. This is the living layer of the tree. If a piece of the bark is removed, it leaves a bare patch where the sap cannot flow upwards taking its nutrirents to the rest of the tree. If a strip of bark from around the entire tree is removed, the tree cannot send any sap upwards and this kills the tree. This is called "girdling" a tree.
In order to harvest the bark in large quatities and make some money, most of the Cascara trees were cut down, then completely stripped of bark by collectors. During World War two, bark was worth 44 cents a kilogram (20 cents a pound), which was much money back then!
Today, few Cascara trees grow in the wild except in parks. Those that do have regrown naturally from seeds left behind as none were planted by humans to replace those that were cut. This is an example of historical un-sustainable harvest.
Because of this overharvest years ago, it is unusual to find a Cascara tree over 10 meters or 30 feet in height. They do grow large if given time.
The chemical in Cascara is anthraquinone which causes peristalsis (movement) in the large intestine.
The whole tree has been used for many things in the past. The Skagit Natives made a green dye with the bark (when cut, the bark turns yellow, then brown with exposure to air and water). Extract from the bark was used to flavor liquors, drinks and ice cream and honey made from the pollen is said to have a laxative effect. The brittle light wood was used by some First Nations as dippers. Today no use has yet been discovered for it.
The whole living tree, however, makes a nice addition to a wildlife garden as it provides a place to make a nest, shelter from predators and food for many species.
Cascara may be found from British Columbia southward along the west side of the Cascade Mts. to northern coastal and Sierran California. It may be found eastward to Idaho and western Montana.