Armillaria ostoyae

Dark honey fungus, honey fungus

Several varieties of honey mushrooms are native to North America. Honey mushrooms spread, like all mushrooms, by extending networks of thin fibers called mycelia underground and into the sapwood of trees. They are pathogenic, invading living trees as well as dead ones, and they spread more widely than most via rhizomorphs. These are specialized mycelia that form thick and tough bundles, sometimes compared to boot laces. The rhizomorphs spread under the bark of trees, over large distances. Honey mushroom mycelial networks form supercolonies, such as one covering over 91 acres in northern Michigan, weighing an estimated 440 tons. Another in Oregon—the “humungous fungus”—is likely the world’s largest living organism, spanning 3.5 square miles, and weighing as much as 35,000 tons.

Identification: These may be parasitic or saprobic, growing on the wood and roots of conifers or some hardwoods. Fruiting is usually in dense clusters. Caps are convex at first, spreading to an umbrella shape, and 1½–3″ (4–8 cm) in diameter. They are brown tinged with orange or pink, with dark brown scales. Gills are initially white, darkening to orange brown. Stems are 2–6″ (6–15 cm) long. They are fibrous and whitish or brownish in color, and up to ⅜″ (1 cm) around. The spore print is white.

Note: Photo 2, Photo 6, and Photo 7 are atypical. First, this species usually appears in clusters. Second, the large bulb at the base is not typically present, perhaps present here because this specimen is single. Third, the cracking on the top of the cap occurs here because very dry weather followed the fruiting, making the cuticle surface brittle. (Thanks to Michaeline Peterson for identifying these.)

Habitats: On hardwoods and conifers in cooler climates, such as northern North America.

Edibility: Some Armillaria species are edible, but they require proper preparation and can be mistaken for toxic species.

Online References:

References:

Armillaria ostoyae description by Thomas H. Kent, not updated.

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