Rhizopogon occidentalis
Ann. Mo. bot. Gdn 5: 14. 1918.
Common Name: none
Misapplied name: Rhizopogon ochraceorubens A. H. Smith
Fruiting body at first hypogeous, then partially erumpent to epigeous; 1.5-6.5 cm broad, irregularly shaped, but usually oval to pulvinate in outline, frequently with bumps or shallow folds; peridium matted-fibrillose, pale yellow to ochraceous, covered by a network of darker rhizomorphs, i.e. yellowish-buff to yellow-brown, in age or when handled, reddish-brown; peridum reddening in KOH; spore-bearing tissue finely textured, firm, pale grey, becoming dingy-olivaceous to ochraceous-brown; at maturity, spongy, sometimes partially liquifying; odor when fresh, of "mushrooms," fruity, suggestive of Suillus pungens, in age, of dirty sweat socks; taste mild; columella absent.
Spores 5-7 x 2-2.5 µm, oblong to elliptical, smooth.
Solitary to clustered under conifers; common under Monterey pine (Pinus radiata) & Bishop pine (Pinus muricata); fruiting throughout the rainfall season, but most common in early fall.
Unknown.
Our most common Rhizopogon species, this pine-inhabiting "false truffle" is recognized by it yellowish to tawny-brown peridium with contrasting, appressed rhizomorphs that typically become reddish to reddish brown in age or from handling.
Desjardin, D.E., Wood, M.G. & Stevens, F.A. (2015). California Mushrooms: The Comprehensive Identification Guide. Timber Press: Portland, OR. 560 p.
Siegel, N. & Schwarz, C. (2016). Mushrooms of the Redwood Coast. Ten Speed Press: Berkeley, CA. 601 p.
Siegel, N., Mohatt, K. & Trudell, S. (2025). Mushrooms of Alaska. Timber Press: New York, NY. 572 p.
Smith, A.H. & Zeller, S.M. (1966). A Preliminary Account of the North American Species of Rhizopogon. New York Botanical Gardens: Bronx, NY. 177 p.
Trappe, J.M., Molina, R., Luoma, D.L., Cázares, E., Pilz, D., Smith, J., Castellano, M.A., Miller, S.L. & Trappe, M.J. (2009). Diversity, Ecology, and Conservation of Truffle Fungi in Forests of the Pacific Northwest. U. S. Department of Agriculture, Forest Service, Pacific Northwest Research Station: Portland, OR. 194 p. (PDF)
Zeller, S.M. & Dodge, C.W. (1918). Rhizopogon in North America. Ann. Missouri Bot. Gard. 5: 1-36. (Protologue)
