Tuber rufum

Sporocarp
Fruiting body hypogeous, 1-2 cm broad, rounded to somewhat flattened, without visible basal mycelium; peridium smooth, finely cracked or areolate (use hand lens), chestnut-brown to dark reddish-brown; gleba solid, firm, pallid when young, becoming marbled light-brown with whitish veins; columella absent; odor when mature and fresh, strong, similar to smoked ham; taste: untried.

Spores
Spores 18-38 x 15-26 µm, oval to elliptical, conspicuously spiny; dark brown in transmitted light, one to six spores per ascus, the latter hyaline and rounded in shape.

Habitat
Solitary to scattered under oaks (Quercus) and conifers; fruiting during the spring or fall.

Edibility
Unknown. Although all species of Tuber are generally assumed to be edible.

Comments
Tuber rufum is distinguished by a smooth, reddish-brown peridium, brown and white marbled gleba (at maturity), and large spiny spores. Rodent diggings are the best guide to finding this attractive, smallish member of the Tuber clan. Although often associated with oaks, we have found one collection with Monterey pine (Pinus radiata). Other Tuber species in our area include Tuber californicum, found in mixed hardwood/conifer woods. It has a whitish, pubescent peridium when young; at maturity it is nearly glabrous and darkens to dull yellow-brown to brown though some of the white ground color usually persists. The spores of Tuber californicum are reticulate rather than spiny. Tuber gibbosum (Oregon white truffle), which can be common under Douglas fir in our area, is a garlic-odored species. It is usually larger than T. rufum, and more irregularly shaped. The peridium is tan to light brown with dark reddish-brown to purple-brown patches; the spores are reticulate.