Cascara (Rhamnus purshiana)

Lushutseed Name: t̕ac̓abac (pronounced ts-ahtc-ah-bahtz)

Location: Near the west end of the Medicinal Garden, next to the small path down to the aquatic section circle of grass.

Identifying Features light: Cascara is a readily identifiable small tree in its native range. It has oval leaves whose tips may be either rounded or abruptly pointed, with a tendency to curl under slightly and small teeth on the margins. The venation is the key to spotting this species, it being quite distinctive. The veins on the bright green leaf are pinnate and profuse, with dozens of secondary veins running off the main central vein. The bark is gray and smooth with lighter stripes, supporting what is often more like a shrub than a tree, although specimens can achieve heights of greater than 40ft (13m). The leaves most often occur in alternate growing pattern. Many of the trees in this genus prefer tropical and subtropical climates, and this is one of the few members of the family that occurs in Washington.

Identifying Features In Depth:

1. Form: A small tree, Cascara Buckthorn may achieve heights of about 40ft (13m), but more often is found as an understory species or shrub. It is known to reach 60ft (20m) in more favorable conditions.

2. Leaves: The leaves of this species are usually found in alternate growing pattern, with an oval shape and rounded to bluntly pointed tips. They are bright green and deciduous in nature and have distinctive pinnate venation running the length of each. Leaves are 2-6 in in length (5-15cm) and 1-2 in in width (2.5-5 cm). Winter buds are lateral and hairy.

3. Bark: The bark of this tree is the source of its best-known medicinal quality (it has extremely laxative properties), and is smooth and gray in color, often with crème-colored streaks.

4. Reproductive Bodies: Small green flowers occur in clusters off slender stalks near the base of the leaf, giving rise small round black fruits of a fleshy nature and with a small point on the side opposite the stem. Each is only about 3 quarters of a centimeter in diameter but contains several seeds. The seeds are bright orange on the inside.

Historical Background: As surprising as it may be, Chronic Constipation affects anywhere from 15-20% of modern Americans, and the ability of the bark of this species to act as a laxative put it in high demand. Of course, the indigenous peoples of the west coast of North America were the first to possess this knowledge, as is almost always the case with medicinal properties of our native trees. However, the first white man to claim credit for “discovering” the laxative qualities of this tree did so in 1877, and its value as a resource quickly increased. In the 20th century, the use of the bark of this tree for medicinal purposes became extremely widespread, taking off especially during World War II, when dried bark was in enormous demand to treat troops overseas. Since Cascara is generally found as an understory tree which is spread throughout the woods, satisfying such demand required employment of “barkers”, usually day laborers, students, or people down on their luck hoping to earn some cash scouring the woods for specimens, most usually in northern California or southern Oregon. The tree was stripped of bark and felled, the effect being that the tree would sprout back from the base (although certainly this practice of harvesting is in general not good for the tree and generally decreased its ability to persist). However, the final felling of the tree following decortication, the act of debarking the tree, is essential as trees left standing following the act almost always perish. Indigenous peoples of the region also discovered that the tree could be applied to sores and swelling, and that the bark could be used to make a greenish yellow dye. The berries are also edible and may be harvested in July and August. Those berries are also favored by small mammals and birds, particularly the pileated woodpecker, and the leaves are occasionally browsed by deer.

Native Range: Cascara Buckthorn occurs in a wide north south range, from southern British Columbia and Vancouver Island south into the mountains of Washington and western flatlands in that state, the Cascade and Coast ranges of Oregon, and the Sierra Nevada and northern coast of California. It may also be found in the Bitterroot range of Idaho.