E-Flora BC: Electronic Atlas of the Flora of British Columbia

Summary:
Features include 1) dark olive-gray to gray-brown cap, 2) white to pale yellow flesh that turns instantly blue when bruised, 3) yellow to olivaceous pores that turn instantly blue when bruised, 4) yellow stem with olive-brown to blackish tints near base, 5) fine reticulation [network pattern] on upper stem, and 6) bitter taste. The description is derived from Bessette except where indicated. According to Siegel(2), based on preliminary genetic analysis, it is possible that Caloboletus frustosus (with salmon to red lower stem) is the same species as Caloboletus conifericola - if so the name Caloboletus frustosus would take precedence (see Caloboletus calopus for further details).

Caloboletus conifericola is found in BC, WA, OR, and AK, (Bessette). It has been reported from ID (A. Parker, pers. comm., K. Chadwick, pers. comm.). Caloboletus conifericola is found rarely in Humboldt and Del Norte counties in CA (Desjardin(6)).

Cap:
7.5-30cm, margin incurved at first; dark olive-gray becoming grayish brown or dark brown, sometimes streaked reddish or blackish; subtomentose to bald, often cracked or cracked-areolate when old, (Bessette), up to 15cm, milky coffee color or "grayish brown to dark brown, at times with slight tinges of red and black, where handled the lighter colors becoming darker brown to blackish"; "outer portions finely diffract", (Dick), surface unpolished to somewhat velvety (Trudell)

Flesh:
white to pale yellow, becoming instantly blue when exposed, (Bessette), "white to pale yellow, with some areas of pinkish or pale red, instantly changing to clear blue"; in stem white or yellow in upper part, more yellow downward, basal part deep reddish brown, changing instantly to clear blue, (Dick)

Pores:
2-3 per mm, round to angular; "pale yellow to olivaceous at first, becoming dingy yellow at maturity, instantly blueing when bruised"; tube layer 1-2.5cm thick, (Bessette), minute; pale yellow, lemon-yellow to olivaceous, later dingy yellow or dingy buff, instantly changing to clear blue and eventually to brown when bruised; tube layer depressed-subdecurrent, the same color except change to brown not mentioned, (Dick)

Stem:
5-12cm x 2-5cm, widening downward or sometimes equal; "pale yellow to yellow with olive-brown to blackish tints near the base, lacking reddish coloration, rapidly blueing when bruised"; finely reticulate [with netted pattern] on upper part or nearly overall, "or sometimes very obscurely reticulate", (Bessette), 11cm long and 4cm wide at top, more or less equal or somewhat bulbous, widest parts up to 5.5cm wide; "pale yellow to yellow, with tinges of reddish brown in scattered areas, the very base olivaceous-brown or dark brown to black, changing everywhere to blue where handled"; subglabrous [nearly bald] or minutely furfuraceous, "finely double-reticulate to the base", (Dick), 10-15cm x 3-6cm (Phillips)

Odor:
not distinctive (Thiers), pleasant (Phillips)

Taste:
bitter (Bessette, Dick)

Microscopic:
spores 12-16.5 x 4-5.5(6) microns, elliptic to oblong-elliptic, pale yellowish green in 2% KOH; cheilocystidia and pleurocystidia scarce, 27-47 x 7-10 microns, "ventricose to ventricose-rostrate with short necks thin or thick, some necks bent or twisted", colorless, a few pale yellow; hyphae of cap surface, flesh, and trama "staining very pale gray to gray in Melzer''s solution, the crosswalls with a distinct peripheral amyloid ring", (Dick), spores 12-17 x 4-6 microns, elliptic to oblong-elliptic, smooth, yellowish, (Bessette)

Spore Deposit:
olive-brown (Bessette)