Czech Mycol. 60(1): 49. 2008.
Common Name: none
Synonym: Boletus chyrsenteron Bull.; Xerocomus chrysenteron (Bull.) Quélet
Cap 4-9 cm broad, convex, becoming nearly plane in age; surface dry, tomentose, dark brown to olive brown, soon areolate, the exposed context pallid at the disc, pinkish near the margin; flesh white, thick, sometimes blueing when bruised; odor mild, taste acidic.
Pores relatively large, 1-2 mm, yellow, olive-brown in age, typically bruising blue.
Stipe 5-10 cm tall, 1.0-1.5 cm thick, dry, smooth to longitudinally ridged, yellowish, with reddish tints usually predominating at the base.
Spores 11.5-14.0 x 4-6 µm, smooth, elliptical to fusiform; spore print olive-brown.
Solitary or in small groups in hardwood/conifer woods from early fall to mid-winter.
Edible, of fair quality.
This drab member of the Boletus clan is recognized by a dark brown-brown to olive-brown areolate cap, and slow, not always consistent blueing of the tubes and cut flesh. Xerocomellus truncatus is a closely related species which cannot be reliably told apart without a microscope although cracks in the cap context tend not to turn pink as in X. chrysenteron. To confirm an identification requires an examination of spores. In Boletus truncatus, as the name suggests, the spores are either blunt or truncate at one end, while in B. chrysenteron they are rounded. Another related species is Xerocomellus zelleri, but it has a darker, less cracked cap at maturity, and a more uniformly red stipe.
Bessette, A.E., Roody, W.C. & Bessette, A.R. (2000). North American Boletes: A Color Guide to the Fleshy Pored Mushrooms. Syracuse University Press: Syracuse, NY. 400 p.
Ladurner, H. & Simonini, G. (2003). Xerocomus s.l. Edizioni Candusso: Alassio. 527 p.
Smith, A.H. & Thiers, H.D. (1971). The Boletes of Michigan. University of Michigan Press: Ann Arbor, MI. 426 p.
Šutara, J. (2008). Xerocomus s. l. in the light of the present state of knowledge. Czech Mycol. 60(1): 29-62.
Thiers, H. D. (1975). California Mushrooms—A Field Guide to the Boletes. Hafner Press: New York, NY. 261 p. (WWW)