Chlorociboria aeruginascens

What You Should Know

Chlorociboria aeruginascens is a beautiful blue-green cup fungus. This mushroom is a common sight, but the fruitbodies are seen only infrequently. This mainly winter-fruiting fungus is sometimes referred to as Green Cup fungus.

Wood infected with Chlorociboria fungi has long been used in such decorative woodworking as Tunbridgeware. In Italy, the practice dates at least to the 14th century, when it was used in 'intarsia', an inlaying process similar to marquetry.

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.

The discoloration is caused by the production of the pigment xylindein, which is classified by chemists as a napthaquinone. This pigment exists in several different forms of various colors within the wood cells; the combination of a yellow-orange form with a blue-green form results in the dazzling blue-green coloration of the colonized wood. Xylindein can inhibit plant germination and has been tested as an algaecide. It may make wood less appealing to termites, and has been studied for its cancer-fighting properties.

Other names: Green Elfcup, Green Wood Cup.

Chlorociboria aeruginascens Mushroom Identification

1. Ecology

   Saprobic on well-decayed, barkless logs and sticks, including those of both hardwoods and conifers; evident as green-stained wood year-round, but the fruiting bodies typically appear in summer and fall; widely distributed in North America.

2. Fruiting Body

   Cup-shaped at first, becoming flattened or disc-shaped; 2-5 mm across; with a tiny stem (1-2 mm long) that may be central or somewhat off-center; upper surface bald, blue-green; undersurface similar.

3. Microscopic Features

   Spores 6-8 x 1-2 µ; subfusiform to nearly cylindric; smooth; biguttulate with a small oil droplet near each end. Paraphyses filiform; 70-80 x 1 µ; apices subacute; hyaline. Terminal cells on excipular surface cylindric; often twisted or contorted; 1-1.5 µ wide; smooth.

Chlorociboria aeruginascens Taxonomy and Etymology

Described in 1869 by Finnish mycologist William Nylander (1822 - 1899), and given the scientific name Peziza aeruginascens, this ascomycetous species was transferred to the genus Chlorociboria in 1957 by American mycologists C S Ramamurthi, R P Korf, and L R Batra.

Synonyms of Chlorociboria aeruginascens include Helvella aeruginosa Oeder ex With., Chlorosplenium aeruginosum (Oeder ex With.) De Not., Peziza aeruginascens Nyl., and Chlorosplenium aeruginascens (Nyl.) P. Karst.

The specific epithet aeruginascens comes from Latin and means 'becoming blue-green', which is what happens to wood that becomes infected with this fungus.

Sources:

Photo 1 - Author: Holger Krisp (Creative Commons Attribution 3.0 Unported)

Photo 2 - Author: Dan Molter (shroomydan) (Creative Commons Attribution-Share Alike 3.0 Unported)

Photo 3 - Author: Jymm (Public Domain)

Photo 4 - Author: Lukas from London, England (Creative Commons Attribution-Share Alike 2.0 Generic)