Austroboletus gracilis

[ Basidiomycetes > Boletales > Boletaceae > Austroboletus . . . ]

by Michael Kuo

This beautiful mushroom is, as its name suggests, more graceful than many other boletes; its stem is typically long and slender. Its pore surface is whitish at first, but becomes pinkish to flesh-colored with maturity. It is mycorrhizal with conifers (and occasionally with hardwoods) in eastern North America.

Under the microscope, Austroboletus gracilis has pitted spores, which is why mycologists have placed it Austroboletus. Previously it belonged in Tylopilus (it certainly is "tylopilesque"), and it will be called Tylopilus gracilis in most field guides.

Austroboletus gracilis is reported as edible in several field guides.

Description:

Ecology: Mycorrhizal with conifers (especially Eastern Hemlock) or sometimes with hardwoods; growing alone or scattered; summer and fall; widely distributed in eastern North America.

Cap: 3-10 cm; convex to broadly convex in age; dry; smooth or felty; sometimes becoming cracked; margin even; reddish brown to cinnamon to dull yellow brown.

Pore Surface: Whitish becoming pinkish to flesh-colored to pinkish brown; bruising brownish; pores circular, 1-2 per mm; tubes to 2 cm deep.

Stem: 7-18 cm long; .5-1 cm thick; gracefully narrowing to apex, or more or less equal; colored like the cap or paler; sometimes slightly curved; frequently longitudinally grooved and/or vaguely reticulate; white at the base.

Flesh: White or pinkish; unchanging when sliced.

Odor and Taste: Taste mild to slightly acidic; odor not distinctive.

Chemical Reactions: Cap surface dark red to orange with ammonia, dark brown with KOH; flesh negative with KOH or ammonia.

Spore Print: Rosy brown.

Microscopic Features: Spores 10-17 x 5-8 µ; minutely pitted (use oil immersion lens); roughly elliptical.

REFERENCES: (Peck) Wolfe, 1979. (Coker & Beers, 1943; Smith & Thiers, 1971, Smith, Smith & Weber, 1981; Weber & Smith, 1985; Phillips, 1991/2005; Lincoff, 1992; Both, 1993; Barron, 1999; Bessette, Roody & Bessette, 2000; Roody, 2003; McNeil, 2006; Ortiz-Santana et al., 2007.) Herb. Kuo 09039502, 09080104, 09150715.

Tylopilus gracilis is a synonym.

Bessette, Roody & Bessette (2000) describe several varieties: Austroboletus gracilis var. flavipes, with more yellowish colors, slightly smaller spores, and no reticulation on the stem; and Austroboletus gracilis var. pulcherripes, with deeper colors and a shorter stem which is coarsely reticulate over the upper two-thirds.

Further Online Information:

Tylopilus gracilis in Smith & Thiers, 1971
Austroboletus gracilis at Macrofungi of Costa Rica
Austroboletus gracilis at Roger's Mushrooms

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Cite this page as:

Kuo, M. (2005, March). Austroboletus gracilis. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/austroboletus_gracilis.html