E-Flora BC: Electronic Atlas of the Flora of British Columbia

Summary:
Features include 1) large size for a truffle, 2) a more or less spherical fruitbody with a fuzzy brown outer surface, 3) a visible convoluted interior, 4) growth usually buried or partially buried especially under mountain conifers, and 5) microscopic characters including smooth broadly elliptic to round spores, on usually 8-spored asci. It is abundant among truffles throughout the Pacific Northwest (Trappe(13)).

It is common in the northern Rocky Mountains, and is also known from CA north to AK, (Smith). Distribution includes OR, ID, CA, MI, and northern Europe, (Gilkey). There are collections at the University of Washington from WA, ID, AK, CO, MI, and UT. There are collections at Oregon State University from WA, OR, ID, AK, AZ, CA, and CO. There are collections at the University of British Columbia from BC. It occurs in WY (Perry), and also in Mexico and Europe (Trappe, M.(3)).

Outer Surface:
2-7cm across, spherical to nearly spherical; pale to dark brown; fuzzy from fine hairs, (Smith), 2-7(10)cm across, spherical or nearly spherical but often squirrel-eaten; "fuzzy or velvety from a coating of light brown to dark brown hairs, usually furrowed", (Arora), 0.5-10cm across, "slightly lobed to strongly convolute"; pale to dark brown; more or less verrucose [warty], coarsely brown-tomentose, the tomentum continuing inward on the folds, (Gilkey)

Stem:
none (Smith)

Interior:
much convoluted; white to whitish streaked with brown, (Smith), "deeply convoluted, the folds often touching each other" but leaving at least some open spaces between them; white to creamy or yellowish tan, "usually streaked with tan or brown", (Arora), comparatively simple to very irregular, "consisting of long labyrinthine canals resulting from folds and projections", that are generally readily separable but sometimes connected and so crowded that the tips of the paraphyses from opposing surfaces meet, (Gilkey)

Odor:
usually mild, but in one form like fermented cider, (Arora), faintly aromatic (Trudell), mild to radish-like or garlicky (Trappe, M.(3))

Microscopic:
spores 18-24 x 10-16 microns, ovoid-elliptic, colorless; asci 8-spored, cylindric, operculate, dehiscent, (Smith), spores 18-27(30) x (10)13-21 microns, "broadly elliptic in one form, round or nearly round in another", smooth, colorless, with one oil droplet; asci forming a distinct palisade lining the empty spaces or canal between the visible folds, usually 8-spored, (Arora), spores 18-24 x 10-16 microns, elliptic to long-elliptic, mostly uniseriate; asci 140-200 x 16-28 microns, "cylindric to somewhat clavate, rounded or somewhat pointed at the apex"; "external wall and folds more or less pseudoparenchymatous between the hymenium and the surface tomentum; outer cells of the cortex colored and larger than the inner colorless cells", (Gilkey), spores 16-21 microns in diameter, elliptic, smooth, (Trappe, M.(3))