Abstract: Method for improved in vivo production of taxanes by inoculation of tissue of the genus Taxus with virulent or avirulent strains of Agrobacterium. In the preferred embodiment, virulent Agrobacterium is the inoculant which induces gall formation at all stages of the plant, from saplings to mature trees. Incomplete harvesting of galls permits regeneration on the trees, resulting in a renewable resource. Unexpectedly, the inoculant tissue (both virulent and avirulent) produces approximately twice the concentration of taxanes per unit tissue weight as compared to normal tissue. In addition, the virulent strain induced gall biomass is 2-3 times greater than normal tissue per unit growth time, while avirulent inoculants show approximately the same growth as normal. The net yield increase is 2-6 times normal, (4-6 for galls), is renewable, does not require special growth hormones or media, does not result in sacrificing the tree, and can be started at the sapling stage.