buckthorn

1. Any of various shrubs or small trees of the genus Rhamnus, which includes several ornamentals and a few medicinal species such as the cascara buckthorn.
2. See bumelia.

[Translation of New Latin cervī spīna : cervī, genitive of cervus, deer, buck + spīna, thorn.]

Description

Buckthorn is the common name for one of several species of shrubs or small trees of the genus Rhamnus that are used for medicinal purposes. The two most common species are R. frangula and R. cathartica.

R. cathartica is also called common or European buckthorn. It was known as a healing herb hundreds of years ago in Anglo-Saxon England, where it was called waythorn, highwaythorn, hartshorn, or ramsthorn. It is also sometimes called purging buckthorn because of its laxative properties. The berries of European buckthorn can be used in healing. The ripe berries of this species are black and the size of a pea.

R. cathartica is a shrubby tree that grows to a height of about 18 ft (6 m). Its twigs are often tipped with small spines, accounting for the "thorn" in its name. Common buckthorn is found throughout Great Britain, continental Europe, and North Africa, where it grows wild in partial sun along the edges of roads and woodlands. It was introduced into North America as an ornamental landscaping plant, but it has naturalized and become a nuisance plant in much of Canada and the northern United States, where its thick growth crowds out native plants.

R. frangula is shorter, wider, and more shrublike than R. cathartica. It grows in damp soil in Great Britain, continental Europe, and parts of Turkey. It also has been imported into North America. Bark from the trunk and branches of R. frangula is gathered and used in preparing a laxative and a hepatic, or liver medication. R. frangula is also called alder buckthorn, black dogwood, frangula bark, alder dogwood, arrow wood, or Persian berries. It is not related to North American dogwood species.

A third species of healing Rhamnus, R. purshianus, grows in western North America and is called California buckthorn. Its bark also produces a laxative that is milder than those derived from either of the other two species. Sea buckthorn, Hippophae rhamnoides, although it is used in healing and shares a common name with these other species, is not related to the Rhamnus buckthorns, nor is it used in the same ways.

General Use

All three types of buckthorn are strong laxatives. The berries of R. cathartica produce the harshest laxative effect (cathartica is a Latin word related to "catharsis", which means purging). The fruit can be used either dried or fresh to treat constipation and to soften stools to give relief from hemorrhoids, anal fissures, or rectal surgery. The berries are also sometimes mixed with other herbs in "blood purifying" formulas.

The dried bark of R. frangula and R. purshianus is also used as laxatives. In earlier times it was used to cleanse the gastrointestinal tract before exploratory surgery. Occasionally buckthorn is used in veterinary medicine as a laxative for dogs.

The laxative effect of all these species is well documented. Buckthorn works by stimulating the large intestine to contract. The contractions shorten the time that waste material remains in the large intestine and allow the formation of softer, moist stools.

In addition to medical uses, buckthorn contains several different pigments used as dyes: yellow from the leaves and bark, green from unripe berries, and blue-gray from ripe berries. R. frangula is also a source of high-quality charcoal used for artistic sketching.

Preparations

The berries of R. cathartica are harvested when ripe. If used fresh, they can be pressed to yield a bitter, extremely foul-tasting juice that can be mixed with sugar and flavorings to produce a laxative syrup. The dried berries are powdered, then added to liquid.

The bark of R. frangula and R. purshianus is harvested in the summer and dried. Young bark is preferred, because the longer the bark is stored, the less potent its laxative properties. Bark used medicinally should be stored at least one year before use. Fresh bark acts as an irritant to the gastrointestinal system. A fluid extract or a decoction is then prepared from the bark and mixed with water and flavorings. The ideal dose is the smallest amount necessary to produce soft stools.

Precautions

Buckthorn should not be used by people suspected of having appendicitis or intestinal obstructions, by pregnant or breastfeeding women, the frail elderly, or children under age 12.

Side Effects

Buckthorn can cause nausea, vomiting, and gastrointestinal spasms in large doses or in sensitive individuals. Buckthorn causes stool to move more rapidly through the large intestine and allows the body less time to reabsorb fluids and electrolytes. Because of this rapid movement, electrolytes can be lost if stools are too frequent and watery. The long-term use of buckthorn can cause potassium imbalances. In rare cases this imbalance can cause heart irregularities, edema, and other serious health reactions.

Interactions

Potassium imbalance is worsened by taking thiazide diuretics, corticosteroids, and licorice root.

Resources

Books

PDR for Herbal Medicines. Montvale, NJ: Medical Economics Company, 1998.

Other

"Plants for the Future: Rhamnus cathartica and Rhamnus frangula." [cited January 17, 2001].

[Article by: Tish Davidson]

The noun has 3 meanings:

Meaning #1: a shrub or shrubby tree of the genus Rhamnus; fruits are source of yellow dyes or pigments

Meaning #2: any shrub or small tree of the genus Bumelia

Meaning #3: an Old World plantain with long narrow ribbed leaves widely established in temperate regions
  Synonyms: English plantain, narrow-leaved plantain, ribgrass, ribwort, ripple-grass, Plantago lanceolata

Buckthorn
Alder Buckthorn (Rhamnus frangula)
Scientific classification
Kingdom:	Plantae
Division:	Magnoliophyta
(unranked):	Eudicots
Order:	Rosales
Family:	Rhamnaceae
Genus:	Rhamnus L.
Species
See text.

Variegated Italian Buckthorn (Rhamnus alaternus 'argenteovariegata')

For the genus Hippophaë, see Sea-buckthorn.

The Buckthorns (Rhamnus) are a genus (or two genera, if Frangula is treated as distinct) of about 100 species of shrubs or small trees from 1-10 m tall (rarely to 15 m), in the buckthorn family Rhamnaceae. They are native throughout the temperate and subtropical Northern Hemisphere, and also more locally in the subtropical Southern Hemisphere in parts of Africa and South America. Some species are invasive outside their natural ranges.

Both deciduous and evergreen species occur. The leaves are simple, 3-15 cm long, and arranged either alternately or in opposite pairs. One distinctive character of many buckthorns is the way the veination curves upward towards the tip of the leaf. The plant bears fruits which are dark blue berries. The name is due to the woody spine on the end of each twig in many species. Buckthorns are used as food plants by the larvae of some Lepidoptera species – see list of Lepidoptera that feed on buckthorns.

Classification

The genus is divided into two subgenera, sometimes treated as separate genera:

• Subgenus Rhamnus: flowers with four petals, buds with bud scales, leaves opposite or alternate, branches with spines. Species include:
  • Rhamnus alaternus – Italian Buckthorn
  • Rhamnus alnifolia – Alderleaf Buckthorn
  • Rhamnus arguta – Sharp-tooth Buckthorn
  • Rhamnus cathartica – Common (or Purging) Buckthorn (syn. R. catharticus)
  • Rhamnus crocea – Redberry Buckthorn (ssp. crocea), Hollyleaf Buckthorn (ssp. pilosa)
  • Rhamnus davurica – Dahurian Buckthorn
  • Rhamnus diffusus
  • Rhamnus globosa – Lokao Buckthorn
  • Rhamnus ilicifolia – Hollyleaf Redberry
  • Rhamnus japonica – Japanese Buckthorn
  • Rhamnus lanceolata – Lanceleaf Buckthorn
  • Rhamnus libanotica
  • Rhamnus lycioides
  • Rhamnus petiolaris - endemic to Sri Lanka
  • Rhamnus pirifolia – Island Redberry Buckthorn
  • Rhamnus prinoides – Shiny-leaf Buckthorn
  • Rhamnus saxatilis – Rock Buckthorn, Avignon Buckthorn, Avignon Berry (syn. R. infectoria, R. infectorius)
  • Rhamnus serrata – Sawleaf Buckthorn
  • Rhamnus smithii – Smith's Buckthorn
  • Rhamnus staddo – Staddo (syn. R. rhodesicus)
  • Rhamnus tinctoria - Dyer's Buckthorn (syn. R. saxatilis ssp. tinctorius)
  • Rhamnus utilis – Chinese Buckthorn

• Subgenus Frangula: flowers with five petals, buds without bud scales, leaves always alternate, branches without spines. Species include:
  • Rhamnus betulaefolia (Frangula betulifolia) – Birchleaf Buckthorn
  • Rhamnus californica (Frangula californica) – California Buckthorn, Coffeeberry
  • Rhamnus caroliniana (Frangula caroliniana) – Carolina Buckthorn, Indian Cherry (syn. R. carolinianus)
  • Rhamnus frangula (Frangula alnus) – Alder Buckthorn, Glossy or Breaking Buckthorn, Black Dogwood
  • Rhamnus glandulosa - Sanguinho
  • Rhamnus latifolia (Frangula azorica)
  • Rhamnus purshiana (Frangula purshiana) – Cascara Buckthorn (syn. R. purshianus)
  • Rhamnus rubra (Frangula rubra) – Red Buckthorn
  • Rhamnus sphaerosperma (Frangula sphaerosperma) – West Indian Buckthorn

Purging Buckthorn Rhamnus cathartica

The Purging Buckthorn or Common Buckthorn (R. cathartica) is a widespread European native species, in the past used as a purgative, though its toxicity makes this a very risky herbal medicine and it is no longer used. Introduced into the United States as a garden shrub, this has become an invasive species in many areas there. It has recently been discovered to be a primary host of the soybean aphid Aphis glycines, a problem pest for soybean farmers across the US. The aphids use the buckthorn as a host for the winter and then spread to nearby soybean fields in the spring.

19th century illustration of R. frangula

Another European species, Alder Buckthorn (R. frangula, syn. Frangula alnus) was of major military importance in the 15th to 19th centuries, as its wood provided the best quality charcoal for gunpowder manufacture.

Italian Buckthorn (R. alaternus), an evergreen species from the Mediterranean region, has become a serious weed in some parts of New Zealand—especially on Hauraki Gulf islands.

Dyer's Buckthorn (R. tinctoria) is used, together with the Asian Chinese Buckthorn (R. utilis), to produce the dye "china green". Another species, Avignon Buckthorn (R. saxatilis) provides the yellow dye Persian berry, made from the berries.

Sanguinho (R. glandulosa) is endemic to the Macaronesian islands, where it is found in the laurisilva forests of the Madeira and Canary Islands.

North American species include Alder-leaf Buckthorn (R. alnifolia) right across the continent, Carolina Buckthorn (R. (F.) caroliniana) in the east, Cascara Buckthorn (R. (F.) purshiana) in the west, and the evergreen California Buckthorn or Coffeeberry (R. (F.) californica) and Hollyleaf Buckthorn (R. crocea) in the west.

In South America, Rhamnus diffusus is a small shrub native from the Valdivian temperate rain forests in Chile.

Buckthorns may be confused with Dogwoods, which share the curved leaf venation; indeed, "dogwood" is a local name for R. prinoides in southern Africa, a plant used to make Ethiopian mead and known as "gesho" in Ethiopia. The two plants are easy to distinguish by slowly pulling a leaf apart; in dogwood thin white latex strings can be seen, strings not present in buckthorn.

External links

Wikimedia Commons has media related to: Buckthorn

Wikisource has the text of the 1911 Encyclopædia Britannica article Buckthorn.

• Scientific chemical research on African Rhamnus
• Rhamnus diffusus pictures from Chilebosque
• Frangula caroliniana images at bioimages.vanderbilt.eduilg

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