[ Ascomycota > Helotiales > Chlorociboriaceae > Chlorociboria ... ]

Chlorociboria aeruginascens

by Michael Kuo, 12 August 2026

I find the blue-stained wood that signifies the presence of Chlorociboria fungi much more often than I actually find the tiny mushrooms themselves. These little blue cup fungi fruit infrequently—but they manage to stain the wood a gorgeous shade of bluish green. The stained wood is distinctive and, when the wood is from an oak tree, sometimes called "green oak."

In North America we have two species of Chlorociboria: Chlorociboria aeruginascens, featured here, and Chlorociboria aeruginosa, which is practically identical to the naked eye but features longer spores and larger, roughened terminal cells on its outer surface.

Chlorosplenium aeruginascens is a synonym.

Description:

Ecology: Saprobic on well-decayed, barkless logs and sticks, including those of both hardwoods and conifers; evident as blue- to green-stained wood year-round, but the fruiting bodies typically appear in summer and fall; originally described from Finland (Nylander, 1868); widespread in Europe, Asia, Oceania, North America, Central America, and South America. The illustrated and described collections are from Michigan, North Carolina, Ohio, and Pennsylvania

Fruiting Body: Cup-shaped at first, becoming flattened or disc-shaped; 1–15 mm across; with a tiny stem or pseudostem.

Upper Surface: Bald; turquoise to pale turquoise.

Excipular Surface: Bald or very finely scurfy (with a lens); slightly paler than the upper surface.

Stem: 2–4 mm long; 1–2 mm thick; turquoise; central or somewhat off-center.

Flesh: Insubstantial.

Odor: Not distinctive.

Microscopic Features: Spores 6–9 x 1–2 µm; subcylindric, cylindric, or with subfusiform ends; smooth; hyaline and biguttulate, with a small oil droplet near each end, in KOH. Asci 55–80 x 4 µm; 8-spored. Paraphyses 1–2 µm wide; filiform; apices subacute or merely rounded; hyaline in KOH. Terminal cells on excipular surface cylindric with rounded apices; often twisted or contorted; 1–2 µm wide; smooth; hyaline in KOH.

REFERENCES: (W. Nylander, 1868) B. B. Kanouse 1947 ex Ramamurthi, Korf & Batra, 1957. (Dennis, 1968; Dixon, 1975; Phillips, 1981; Smith, Smith & Weber, 1981; Breitenbach & Kränzlin, 1984; Arora, 1986; Imazeki et al., 1988; Valenzuela, 1990; Phillips, 1991/2005; Schalkwijk-Barendsen, 1991; Lincoff, 1992; Barron, 1999; Roody, 2003; Johnston & Park, 2005; McNeil, 2006; Miller & Miller, 2006; Binion et al., 2008; Trudell & Ammirati, 2009; Buczacki et al., 2012; Beug, Bessette & Bessette, 2014; Tudor et al., 2014; Desjardin, Wood & Stevens, 2015; Siegel & Schwarz, 2016; Baroni, 2017; Gminder & Böhning, 2017; Woehrel & Light, 2017; Elliott & Stephenson, 2018; Sturgeon, 2018; Læssøe & Petersen, 2019; Maggio et al., 2012; McKnight et al., 2021; MacKinnon & Luther, 2021.) Herb. Kuo 07171002, 07221402, 08091905, 08111902, 09252102.

This site contains no information about the edibility or toxicity of mushrooms.

Spores

Asci and paraphyses

© MushroomExpert.Com

Cite this page as:

Kuo, M. (2026, August). Chlorociboria aeruginascens. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/chlorociboria_aeruginascens.html