Chlorociboria aeruginascens (Nyl.) Kanouse ex C S Ramamurthi, R P Korf & L R Batra - Green Elfcup

Phylum: Ascomycota - Class: Leotiomycetes - Order: Helotiales - Family: Insertae sedis (placement uncertain)

Chlorociboria aeruginascens, Green Elfcup, southern England

The green-stained wood that is evidence of Green Elfcup, Chlorociboria aeruginascens, 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.

Chlorociboria aeruginascens, Green Elfcup, Wales, UK


In Britain and Ireland Chlorciboria aeruginascens is one of just two species recorded in the genus Chlorociboria, the other being Chlorociboria aeruginosa. Both result in green staining. Although C. aeruginosa tends to be a little smaller and very much rarer than C. aeruginascens, the fruitbodies of the two species cannot be confidently differentiated on macroscopic characteristics, but at 5-7 x 1-2µm the spores of Chlorciboria aeruginascens are significantly smaller than those of Chlorciboria aeruginosa (9-14 x 2- 4µm).

Both species are more often seen in the form of green-stained wood than when producing fruitbodies.

This ascomycetous fungus has a very wide geographical distribution that includes Europe and North America.

Taxonomic history

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.

Identification guide

Fruitbody of Green Elfcup


Initially shaped like a goblet with a very short stem that is usually central or slightly off centre, the fruitbodies flatten with age and develop wavy edges. Individual fruit bodies are 0.5 to 1cm in diameter and usually less than 1cm tall.

The upper, fertile surface is bright green and smooth, while the underside of the cup and the stipe are felty and pale blue-green, darkening with age.

Asci and paraphyses of <em>Chlorociboria aeruginascens</em>


Eight-spored; typically 65 x 5µm.


Narrow, clavate. (Paraphyses are structures of sterile tissue between the asci on the hymenial surface.)

Show larger image

Spores of Chlorociboria aeruginascens


Fusiform, smooth, 5-7 x 1-2µm, with oil droplets visible at either end.

Show larger image

Spore print


Not distinctive.

Habitat & Ecological role

Saprobic, on bark-free dead wood, particularly oak, beech and hazel.


The green stain is visible all the year round, but fruitbodies occur infrequently and mainly in autumn.

Similar species

Chlorociboria aeruginosa is very similar and can only be separated with confidence by microscopic examination of spore dimensions.

Several darker cup-like ascomycetes fungi, including Bulgaria inquinans, occur in similar habitats.

Reference Sources

Fascinated by Fungi, 2nd Edition, Pat O'Reilly 2016, reprinted by Coch-y-bonddu Books in 2022.

Dictionary of the Fungi; Paul M. Kirk, Paul F. Cannon, David W. Minter and J. A. Stalpers; CABI, 2008

Taxonomic history and synonym information on these pages is drawn from many sources but in particular from the British Mycological Society's GB Checklist of Fungi.


This page includes pictures kindly contributed by David Kelly.

Top of page...

Fascinated by Fungi, 2nd edn, hardback

Fascinated by Fungi. Back by popular demand, Pat O'Reilly's best-selling 450-page hardback book is available now. The latest second edition was republished with a sparkling new cover design in September 2022 by Coch-y-Bonddu Books. Full details and copies are available from the publisher's online bookshop...

© 1995 - 2024 First Nature: a not-for-profit volunteer-run resource

Please help to keep this free resource online...

Terms of use - Privacy policy - Disable cookies - Links policy