Description and Natural History of the English and Pacific Yews

Taxus baccata and Taxus brevifolia are members of the yew family (Taxaceae). T. baccata is commonly known as the English yew; it's native to (you guessed it) England, but has been introduced to some parts of Northeastern U.S. (mainly Vermont). T. brevifolia is most commonly known as the Pacific Yew, but it may also be referred to as the Western or American yew (however, the tree most typically called American yew is T. canadiensis). To further complicate matters, the Pacific yew may be classified as T. braccata brevifolia, T. bourcieri, or T. lindleyana in older literature. The Pacific yew grows in moist soils in British Columbia, Alaska, California, Idaho, Montana, Oregon, and Washington. Many populations are in potentially serious decline.

Like other members of Taxus, these yews produce red, berrylike fruits instead of cones and have flat, evergreen needles that grow all around the stem. Their wood is hard, durable and elastic. The Pacific yew's population decline is mostly due to its long-time popularity with woodworkers and furniture makers, but its situation has gotten worse since the FDA designated it the only approved source of paclitaxel (Taxol), an anticancer drug that has gained a lot of attention.

The bright red fruits of yews are called arils and each cups a single seed. The arils, which are moderately sweet, are the only parts of the plant that do not contain poisonous alkaloids called taxines. The seeds are deadly, so it is not recommended that people eat the arils.

Paclitaxel's anticancer properties were first discovered in the 1960s as a result of a huge plant-screening program initiated by the National Cancer Institute (NCI). Researchers further identified its specific functions (it keeps fiber-like cell structures called microtubules from breaking down) in 1979, and clinical trials to test its safety started in 1983. The compound has been identified in lesser quantities in other yew species such as the American yew and T. cuspidata, the Japanese yew. The English yew contains a similar compound called docetaxel, which is marketed under the name Taxotere.

Historically, Native American tribes used yew brews to treat rheumatism, fever, and arthritis. The Japanese used yew leaves to treat diabetes and to induce abortions.

No one should attempt self-medication with any species of yew, because they are way too poisonous.

For more information, visit:

Medical Attributes of Taxus brevifolia - The Pacific Yew

References:

Duke, James A., and Edward S. Ayensu. 1985. Medicinal Plants of China. Algonac, MI, Reference Publications, Inc.

Flora of North America Editorial Committee. 1993. Flora of North America. Oxford, UK, Oxford University Press.

1995 Physician's Desk Reference ©. Montvale, NJ, Medical Economics Data Production Company.

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