Major Groups > Polypores > Hapalopilus nidulans


Hapalopilus nidulans

[ Basidiomycetes > Polyporales > Hapalopilaceae > Hapalopilus . . . ]

by Michael Kuo

This nondescript, fleshy, orangish polypore is often overlooked; it tends to blend in with its surroundings. A drop of KOH anywhere on the fruitbody, however, produces a rather stunning color change to purple or lilac (see the illustration). Truth be told, KOH is probably not required for successful identification--but it's fun! Like viewing the horned cystidia of Pluteus cervinus or watching the sea-green color change of Boletus separans in ammonia, it's one of those things a true mushroom geek never tires of.

Absent the KOH reaction, Hapalopilus nidulans is recognized by its dull orange colors, its fairly fleshy consistency, the absence of a stem, and the small, angular pores. In eastern North America it is found on hardwood logs and debris, but in the southwest it favors conifer wood.


Ecology: Saprobic; growing alone or in small groups on decaying logs and sticks; on hardwood debris in the east, or conifer wood in the southwest; causing a white rot; spring to fall, or over winter in warmer climates; widely distributed east of the Rocky Mountains, and occasionally reported in the southwest and Pacific Northwest.

Cap: 2.5-12 cm across; irregularly bracket-shaped or kidney-shaped; convex; smooth or finely hairy; dull orange to dull cinnamon.

Pore Surface: Dull orange to dull cinnamon; not bruising; with 2-4 angular pores per mm; tubes to 1 cm deep.

Stem: Absent.

Flesh: Dull orange or paler; watery and soft at first, but later quite tough and hard.

Chemical Reactions: All parts purple to lilac with KOH.

Spore Print: White.

Microscopic Features: Spores 3.5-5 x 2-3 µ; smooth; elliptical to cylindrical; inamyloid; hyaline in KOH. Hyphal system monomitic, with conspicuous clamp connections.

REFERENCES: (Fries, 1821) Karsten, 1881. (Overholts, 1953; Smith, Smith & Weber, 1981; Arora, 1986; Gilbertson & Ryvarden, 1986; Phillips, 1991/2005; Lincoff, 1992; Roody, 2003; McNeil, 2006; Binion et al., 2008.) Herb. Kuo 07160304, 07060701, 06260902.

Polyporus nidulans is a former name; Hapalopilus rutilans is a synonym.

Further Online Information:

Hapalopilus nidulans at Roger's Mushrooms


Hapalopilus nidulans

Hapalopilus nidulans

Hapalopilus nidulans

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Cite this page as:

Kuo, M. (2003, August). Hapalopilus nidulans. Retrieved from the MushroomExpert.Com Web site: