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Boletus chrysenteron

[ Basidiomycetes > Boletales > Boletaceae > Boletus . . . ]

by Michael Kuo

This common bolete is fairly widely distributed in North America, and can be recognized by its brown to olive brown, cracked cap; pinkish to reddish flesh is exposed in the cracks, separating it from most other boletes with oft-cracked caps. The two closest look-alikes are Boletellus chrysenteroides, which has a darker cap and grows from decaying wood, and Boletellus pseudochrysenteroides, which has a rosy red cap. Both of these look-alike species have ribbed spores, making them easily separable from Boletus chrysenteron with microscopic analysis.

Boletus chrysenteron is edible, but it is a blue stainer and should be avoided by beginners. And even though it is edible, it is not very good; I don't recommend it.

I am treating two virtually indistinguishable (putative) species together here; Boletus chrysenteron is described below, followed by comments distinguishing Boletus truncatus.

Description:

Ecology: Mycorrhizal with hardwoods; growing scattered or gregariously; summer and fall, according to most authors; widely distributed in North America. According to Smith & Thiers (1971), growing "on earth exposed for 3-5 years, such as around uprooted trees, along roadsides, on mossy banks, etc., in hardwood and mixed forests, common during some seasons, rare during others" (260).

Cap: 3-8 cm; convex, becoming broadly convex or almost flat; dry; finely velvety when young; becoming cracked in age, usually conspicuously, with reddish to pinkish flesh showing in the cracks, especially towards the margin; brown to olive brown, rarely reddish overall; marginal area often reddish in age.

Pore Surface: Yellow when young, becoming brownish or olive, sometimes with reddish areas in age; bruising blue, sometimes slowly; 1 pore per mm; tubes to 1 cm deep.

Stem: 4-6 cm long; .5-1 cm thick; more or less equal, or tapering to base; solid; yellow above, reddish below; purplish red at base; basal mycelium white; not reticulate, but sometimes with a few ridges; bruising blue-green.

Flesh: White when young, yellow in age; staining slowly bluish on exposure.

Odor and Taste: Not distinctive.

Chemical Reactions: Cap dark brown to black with KOH, dull brown with ammonia. Flesh lemon yellow or olive with iron salts, buff with KOH.

Spore Print: Olive brown.

Microscopic Features: Spores 9-13 x 3.5-4.5 µ; smooth; subfusiform to boat shaped.

REFERENCES: Bulliard, 1789. (Coker & Beers, 1943; Snell & Dick, 1970; Smith & Thiers, 1971; Thiers, 1975; Smith, Smith & Weber, 1981; States, 1990; Phillips, 1991/2005; Lincoff, 1992; Both, 1993; Evenson, 1997; Barron, 1999; Bessette, Roody & Bessette, 2000; Wood & Stevens, 2003; McNeil, 2006; Miller & Miller, 2006.) Herb. Kuo 07189401.

Xerocomus chrysenteron is a synonym.

Boletus truncatus, also widely distributed, is virtually indistinguishable without a microscope; its spores are larger (10-15 x 5-7 µ) and frequently truncated, with a small apical pore. According to Wood & Stevens (2003), it is less likely to develop pinkish tones in the cracks, and bruises more quickly and intensely. Lincoff (1992) distinguishes Boletus truncatus microscopically and by its "abruptly tapering stalk base" (567).

Smith & Thiers (1971) record a variety from Michigan, Boletus chrysenteron var. subnudipes, based on the microscopic appearance of cells in the cap skin.

Further Online Information:

Boletus chrysenteron and variants in Smith & Thiers, 1971
Boletus truncatus in Smith & Thiers, 1971
Boletus chrysenteron at MykoWeb
Boletus truncatus at MykoWeb
Boletus chrysenteron at Roger's Mushrooms
Xerocomus chrysenteron at Fungi of Poland

 

Boletus chrysenteron

Boletus chrysenteron

Boletus chrysenteron



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Cite this page as:

Kuo, M. (2007, January). Boletus chrysenteron. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/boletus_chrysenteron.html