Taxus brevifolia otherwise known as Pacific yew or Western yew is a conifer and originates from the Pacific Northwest of North America. The chemotheraphy drug paclitaxel (taxol) is derived from Pacific Yew. This is the most well known cancer drug and the molecule important in the fight against cancer is 10-deacetyl-baccatin III.  Pacific Yew was already scarce when its potential to fight against cancer was discovered and as a result scientists not derive the taxol needed to fight cancer from close relatives of the plant.