Taxaceae
Taxus brevifolia
Pacific yew · Western yew
- Part used
- barkleaf
- Native range
- Pacific northwest of North America, from Alaska to California
- Morphology
- A slow-growing understorey conifer, rarely more than fifteen metres, with flat dark needles and a fleshy red aril instead of a cone. Every part is toxic except the red flesh of the aril.
What is in it
Evidence
Paclitaxel, isolated from the bark, is a major chemotherapy agent for ovarian, breast and lung cancer. This is a statement about the drug and not about the tree.
Safety
Taxine alkaloids are cardiotoxic and yew poisoning is frequently fatal, with little to be done once absorbed. Ingestion of foliage or seed is a recognised cause of death in both livestock and people. Nothing about this plant is safe to prepare or take.
Regulatory: Not a permitted medicine ingredient. Paclitaxel is a prescription cytotoxic agent.
Historical use
Used by several Pacific Northwest peoples for tools and bows and in some medicinal preparations. Yew species in Europe carry a long association with churchyards, longbows and poisoning rather than with medicine.
Recorded as history and attributed where possible. Long use establishes that a plant was widely used, not that it worked, and not that it was safe.
Worth knowing
Paclitaxel came out of a mass screening programme rather than out of a tradition — the US National Cancer Institute collected tens of thousands of plant samples in the 1960s, and this was one of them. Nobody was using yew bark for cancer.
The supply problem then became the story. Extracting enough paclitaxel for one patient took several mature trees, each of which had grown for a century or more, and the drug's success threatened the species that produced it. It was solved by semi-synthesis from a renewable precursor in the needles of European yew, and later by plant cell culture. That is the pattern this section keeps returning to: the tradition or the wild population points at the molecule, and then chemistry has to take over before the demand destroys the source.
Nomenclature verified against GBIF backbone taxonomy.