|Major Groups > Boletes > Boletus > Boletus luridus|
by Michael Kuo
Boletus luridus, associated primarily with oaks in eastern North America, is an impressive, blue-staining bolete with a red pore surface, a brownish cap, and a stem decorated with prominent reddish reticulation. This admittedly broad description encompasses several hardwood-associated species that have been named on the basis of minor differences in physical features; see the comments below if you are bound and determined to push aside my "Boletus luridus" umbrella and get wet with the details.
Ecology: Mycorrhizal with oaks and perhaps with other hardwoods; growing alone, scattered, or gregariously; summer and fall; widely distributed in eastern North America; also documented in Central America.
Cap: 5-20 cm, convex to broadly convex in age; dry or slightly sticky in wet weather; finely velvety or smooth; variable in color but frequently olive-brown, brown, reddish brown, or yellowish; bruising blackish or blue.
Pore Surface: Yellow or red when very young; red to orange at maturity; bruising blue; 1-3 pores per mm; tubes yellowish to olive, to 15 mm deep.
Stem: 4-15 cm long; up to 3 cm thick; tapering to the apex but not typically club-shaped; prominently reticulate with vertically elongated reddish reticulation; often with a velvety base; yellowish above and reddish below; sometimes brownish or purple-red near the base; bruising and discoloring blue.
Flesh: Whitish to yellow; sometimes reddish in the stem; bluing when sliced.
Odor and Taste: Not distinctive.
Chemical Reactions: Ammonia negative on cap; negative (but erasing blue) on flesh. KOH dark red to black on cap; orange to yellow on flesh. Iron salts olive to grayish on cap; negative (but erasing blue) on flesh.
Spore Print: Olive brown.
Microscopic Features: Spores usually 11-15 x 5-7 µ but sometimes nearly twice as large; smooth; broadly subfusiform to nearly elliptical.
REFERENCES: Schaeffer, 1774. (Fries, 1821; Saccardo, 1888; Snell & Dick, 1970; Smith & Thiers, 1971; Smith, Smith & Weber, 1981 Both, 1993; Bessette, Roody & Bessette, 2000; Binion et al., 2008.) Herb. Kuo 07140402, 08240507, 07010701.
Boletus vinaceobasis, described by Smith & Thiers (1971), has smaller spores (9-12.5 X 5.5-6 µ) and cystidia that appear dark brown when viewed in a Melzer's mount. Boletus carminiporus, described by Bessette, Both & Dunaway (1998), has flesh that does not stain blue when sliced (though its pore surface bruises blue). Boletus rhodosanguineus, described by Both (1998), is mycorrhizal with red oaks, has a stocky stem, a pore surface that is red but features a contrasting yellow marginal zone, and a consistently dull brick red cap.
Further Online Information:
Cite this page as:
Kuo, M. (2007, February). Boletus luridus. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/boletus_luridus.html