Mycologia 58: 825. 1966.
Common Name: none
Synonym: Buchwaldoboletus orovillus comb. prov.
Cap 8-15 cm broad, convex, becoming plano-convex; margin at first incurved, then decurved, often overlapping the tubes, even to wavy, sometimes slightly upturned at maturity; surface sticky when moist, otherwise dry, glabrous or with faint appressed fibrils, occasionally areolate; color when fresh, bright sulphur-yellow, fading to dull yellow, the disc often tinged pale brown; cuticle peelable from the underlying context, the latter up to 2 cm thick; context relatively soft, yellowish, young material quickly bluing when cut or injured, in age bluing erratically or not at all, sometimes vinaceous-pink above the tube layer; odor and taste mild.
Tubes 0.5-1.0 cm long, yellowish-olive, bluing when injured; pores angular, at maturity, approximately 1 per mm, yellow when young, becoming ochraceous-brown to dull reddish-brown, dark-brown in age; young pores readily bluing.
Stipe 5-9 cm long, 2.5-4.5 cm broad, solid, fleshy, equal, clavate, ventricose, or tapered to a pointed base; surface of apex smooth, sometimes ridged by tube scars, not reticulate, yellowish, occasionally tinged reddish-brown, elsewhere smooth to appressed fibrillose, yellowish with brownish to reddish-brown tints, discoloring dark- brown where handled, the base yellowish with adhering yellowish-brown mycelium; context usually bluing when cut, but in age erratically so or not at all; partial veil absent.
Spores, 5.5-6.5 x 3.5-4.0 µm, elliptical, smooth, inamyloid. Spore print olive-brown.
Solitary or in small clusters, growing at or near the base of Monterey pine stumps or on wood chips; fruiting in late summer.
This bright yellow bolete is a uncommon and striking find. Unusual for boletes in our area, it appears before the fall rains, perhaps utilizing moisture from the dying roots of Monterey pine stumps near which it fruits. Thiers originally described this species as having red pores, but later amended the description to cover a variant that has yellowish to yellowish-brown pores. Local material fits the amended description. An interesting aspect of this mushroom is that fresh material bruises blue quickly, but at maturity, the bluing reaction becomes faint or nonexistent.
Boletus orovillus is closely related to the European Buchwaldoboletus lignicola and Buchwaldoboletus sphaerocephalus, and will probably eventually be transferred to that genus. It differs from the European species by its visid rather than dry cap and shorter spores.
Desjardin, D.E., Wood, M.G. & Stevens, F.A. (2015). California Mushrooms: The Comprehensive Identification Guide. Timber Press: Portland, OR. 560 p.
Thiers, H.D. (1966). California boletes II. Mycologia 58(6): 815-826. (Protologue)
Thiers, H.D. (1975). California Mushrooms—A Field Guide to the Boletes. Hafner Press: New York, NY. 261 p. (WWW)