Summary:
Features include 1) a spherical to lobed minutely velvety fruitbody that is whitish to yellowish or brownish, 2) an interior varying from a simple cavity with a prominent opening to a very convoluted interior, whitish at first but the fertile tissue often brownish to pinkish orange at maturity, 3) growth in soil or inside very rotten wood, and 4) microscopic characters including elliptic spores that are pitted and wrinkled, borne on typically 8-spored asci. Var. variiformis is orange brown, and var. pallida is white to cream when young and pale, dull orange when fully mature, (Trappe, M.(3)). Hydnotrya variiformis is common among truffles in the Pacific Northwest (Trappe(13)).

Interior:
"variable in configuration, but small specimens often containing a simple cavity with a prominent opening, and larger ones usually with several chambers or narrow, branching canals formed by crowding and infolding of the outer wall; canals usually empty but their sides often fused; white or pallid but the hymenium (fertile tissue) often brownish to pinkish-orange at maturity", (Arora), "simple with a single opening to complexly convolute and internally divided into many cavities with several openings"; somewhat paler than exterior, (Gilkey(3)), from "simple cavity and conspicuous opening" to "extremely lobed with interior cavity reduced to many small chambers and narrow branching canals among crowded and fused folds, opening obscurely to the surface at several points", (Gilkey(2)), interior "convoluted with several chambers, tissue fragile and brittle", (Trappe, M.(3) for var. pallida)

Odor:
not distinctive (Trappe, M.(3) for var. pallida)

Taste:
not distinctive (Trappe, M.(3) for var. pallida)

Microscopic:
spores "32-36 x 24-28 microns, elliptical, smooth becoming minutely pitted and wrinkled at maturity, yellowish-brown under the microscope", non-amyloid asci in palisade that lines the canals or cavity, typically 8 spored, (Arora), spores 32-36 x 24-28 microns, elliptic, minutely and irregularly lacunose-rugose, yellow-brown, uniseriate when mature; asci 240-280 microns long, somewhat clavate at first, becoming cylindric; paraphyses 6 microns wide, extending 120-140 microns beyond asci, slightly enlarged at tip; cortex pseudoparenchymatous without, changing to "intertwined, branching hyphae running perpendicular to asci", (Gilkey(2)), 25-30 x 10-15 microns, elliptic, "colorless to pale yellow and enclosed in an amorphous sheath decorated with scattered, tiny pits", (Trappe, M.(3) for var. pallida)

Notes:
It is found from southern BC to northern CA and the Rocky Mountains, (Trappe(13)). It has been reported frequently from OR to the Oregon Truffling Society. It was reported from WA by Jumpponen(1), from OR by J. Smith et al., from WY by Fogel(7), and given for OR, CA, and WY by Gilkey(3). There are collections from BC at the Pacific Forestry Centre and the University of British Columbia.

Synonyms and Alternate Names:
Ceracea crustulina Bourdot & Galzin