Tuber oregonense, commonly known as the Oregon white truffle, is a species of edible truffle in the genus Tuber. Described as new to science in 2010, the North American species is found on the western coast of the United States, from northern California to southern British Columbia west of the Cascade Range. A mycorrhizal fungus, it grows in a symbiotic association with Douglas fir. It overlaps in distribution with the closely related T. gibbosum, but they have different growing seasons: T. oregonense typically appears from October through March, while T. gibbosum grows from January to June. The fruit bodies of the fungus are roughly spherical to irregular in shape, and resemble small potatoes up to in diameter. Inside the truffle is the gleba, which is initially white before it becomes a marbled tan color. The large, often thick-walled, and strongly ornamented spores are produced in large spherical asci. The truffle is highly prized for its taste and aroma. Some individuals have claimed success in cultivating the truffles in Christmas tree farms. Taxonomy and phylogeny The species was first officially described and named in a 2010 Mycologia article, although T. oregonense had been previously used provisionally (as Tuber oregonense Trappe & Bonito) in American field guides and other popular publications for several years. The type specimen was collected from Benton County, Oregon, on 3 February, 2007 along U.S. Route 20 in Oregon. The specific epithet oregonense derives from the name Oregon and the Latin suffix -ense (relating to), in reference to western Oregon being its central region of abundance. The fungus is commonly known as the Oregon white truffle. Truffle authority James Trappe initially intended to name the species as a variety of T. gibbosum (i.e., as Tuber gibbosum var. oregonense) before molecular analysis revealed that genetic differences warranted distinction at the species level. Tuber oregonense is part of the gibbosum clade of the genus Tuber, which contains species that have "peculiar wall thickenings on hyphal tips emerging from the peridial surface at maturity." Description The fruit bodies of T. oregonense are hypogeous (growing in the ground), typically broad, although specimens up to have been recorded. Smaller specimens are spherical or nearly so, and have random furrows; larger specimens are more irregular in shape, lobed and deeply furrowed. Young fruit bodies have a white peridium, as the truffle matures it develops red to reddish-brown or orangish-brown patches; with age it becomes