Pacific yew trees (Taxus brevifolin) 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. Here the bark is ground up before prior to taxol being extracted and purified.