Boletopsis grisea

What You Should Know

Boletopsis grisea is a species of fungus in the family Bankeraceae. The fruit bodies are gray, fleshy polypores that grow on the ground in a mycorrhizal association with Scots pine (Pinus sylvestris). It is found in Asia, North America, and Europe.

This mushroom is edible but frequently bitter. The Japanese soak this mushroom in brine to remove the bitterness. Long boiling does not reduce the bitter flavor.

Boletopsis grisea is most likely to be confused with other fleshy, terrestrial polypores, two of which are Albatrellus flettii and Jahnoporus hirtus. The former differs in having a bluish cap, and salmon-colored pores in age, while Jahnoporus hirtus has a gray-brown, occasionally purple-brown, tomentose cap. Microscopically, Boletopsis grisea is easily distinguished by its nodulose spores.

Research has identified p-terphenyl compounds that impart a free radical scavenging activity in laboratory tests. Eight phenolic compounds have been isolated and identified from the fruit bodies, including three that inhibit the enzyme 5-lipoxidase.

Other names: Grey Falsebolete.

Boletopsis grisea Mushroom Identification

1. Pileus

   Cap 5.0-13.0 cm broad, convex, broadly so in age, often irregular with depressed and raised areas; margin incurved, then decurved, wavy; surface dry, glabrous to patchy appressed-fibrillose, pallid when unexposed, soon grayish to blackish-brown, sometimes with purplish tints, darker where handled; context white, firm, up to 3.0 cm thick at the disc, unchanging to slowly pale-gray; odor mild to fragrant; taste frequently bitter.

2. Hymenophore

   Pores fine, 3-4/mm, mostly angular, whitish, darkening when bruised; tube layer subdecurrent, 1.0-3.0 mm thick, not readily separable from the cap context.

3. Stipe

   Stipe 3.0-8.0 cm long, 2.0-4.0 cm thick, solid, central or eccentric, equal to ventricose, the base often pointed; surface colored like the cap but usually lighter, glabrous to squamulose, bruising dark grayish-brown; context white, firm, unchanging when cut except grayish at the base; partial veil absent.

4. Spores

   Spores 5.0-6.0 x 4.0-5.0 µm, subglobose with a nodulose surface, inamyloid; spores hyaline to pale-tan in deposit.

5. Habitat

   Solitary, scattered, or in cespitose clusters in mixed hardwood-conifer woods; fruiting from late fall to mid-winter in coastal and montane forests; widely distributed; uncommon.

Boletopsis grisea Taxonomy

The fungus was first described in 1874 as a species of Polyporus by American mycologist Charles Horton Peck in 1874, who made the type collection in Copake, New York. Appollinaris Semenovich Bondartsev and Rolf Singer transferred it to Boletopsis in 1941.

Sources:

Photo 1 - Author: caspar s (Creative Commons Attribution 2.0 Generic)

Photo 2 - Author: Ron Pastorino (Creative Commons Attribution-Share Alike 3.0 Unported)

Photo 3 - Author: caspar s (Creative Commons Attribution 2.0 Generic)

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