farms in Oregon. Techniques reportedly involve inoculating the ground under young Douglas fir trees with a slurry comprising ground-up truffles mixed in water, or the feces of animals fed truffles, but no concrete evidence shows these methods can be used to establish new truffle patches or to improve the productivity of existing patches. References Cited texts External links North American Truffling Society Side-by-side comparison of T. oregonense and T. gibbosum Fungi described in 2010 Fungi of North America Oregon culture Truffles (fungi) oregonense