Pacific yew forest (Taxus brevifolin) in the Pacific Northwest. Pacific yew trees were once the subject of an environmental controversy over the production of Taxol, also known as Paclitaxel, a chemotherapy drug used to treat a variety of cancers. It took 30,000 pounds of bark from 2,000 - 4,000 of the slow-growing trees, which can take decades to reach shoulder height, to produce just one kilogram of taxol. The trees are no longer involved in its production.