Initial attempts to broaden its sourcing used needles from the tree, or material from other related Taxus species, including cultivated ones, but these attempts were challenged by the relatively low and often highly variable yields obtained. Source: Internet
While both the size of the wild population of Taxus brevifola and the magnitude of the eventual demand for taxol were uncertain, it was clear for many years that an alternative, sustainable source of supply of the natural product would be needed. Source: Internet