Xylaria hypoxylon (L.) Grev. - Candlesnuff Fungus

Phylum: Ascomycota - Class: Sordariomycetes - Order: Xylariales - Family: Xylariaceae

Xylaria hypoxylon - Candlesnuff Fungus

Xylaria hypoxylon, commonly called the Candlesnuff Fungus, appears throughout the year but is particularly noticeable during late autumn and winter. This ubiquitous little rotter is one of the pyromycetes or flask fungi and one of the last fungi to attack rotting wood; it is often preceded by a succession of other species such as Honey Fungus (Armillaria mellea and it relatives) and Sulphur Tuft (Hypholoma fasciculare).

Xylaria hypoxylon - Candlesnuff Fungus, Scotland

Rarely fruiting in photogenic groups, this morbid fungus is the type species of the Xylaria genus. It need hardy be mentioned that these tough but insubstantial fungi are not generally considered to be edible.

Xylaria hypoxylon

Distribution

A very common species in Britain and Ireland, Xylaria hypoxylon is found also throughout mainland Europe and in many parts of North America.

While physically it seems to suggest a relevant physical comparison, the common name Candlesnuff Fungus is something of an enigma. It suggests something that once emitted light but no longer does so; however, in reality it is a bioluminescent fungus, and in a really dark place it can be seen to emit light continually as phosphorus accumulated within the mycelium reacts with oxygen and other chemicals in the fungus. Unfortunately the amount of light from this and most other bioluminescent fungi is very weak indeed, and to see it clearly you need either an image intensifier (such as those built in to night sights used by soldiers and spies) or to take a long-exposure photograph in a totally dark room.

Some fungi - Armillaria mellea the Honey Fungus is one such example - give out enough light to be visible to the human eye, but only on very dark, cloudy and moonless nights in dense woodland where light pollution from other sources is at an absolute minimum. Probably the easiest way to get to see fungal bioluminescence is to cut through a piece of wood that is being consumed by bioluminescent fungi; this is because the mycelium emits light more strongly than the fruitbodies do. The ghostly greenish colour of light from bioluminescent mushrooms, toadstools and other fruitbody forms must surely have contributed something to the many dark myths associated with the underworld kingdom of fungi.

Xylaria hypoxylon, close-up picture of conidia

Taxonomic history

The scientific name Clavaria hypoxylon was given to this ascomycetous fungus in 1753 by Carl Linnaeus, but its currently accepted name Xylaria polymorpha dates from 1824, when Scottish mycologist and illustrator Robert Kaye Greville (1794 - 1866) transferred Dead Man's Fingers to the genus Xylaria.

Synonyms of Xylaria hypoxylon include Clavaria hypoxylon L., Sphaeria hypoxylon (L.) Pers., Sphaeria ramosa Dicks., and Xylosphaera hypoxylon (L.) Dumort.

Etymology

The genus name Xylaria comes from the Greek noun X├Żlon meaning wood - from the same source as the word xylem, which is the wood of a tree that transports water and nutrients from the roots up to the branches, twigs and leaves. The specific epithet hypoxylon comes from hypo- meaning beneath (or less than) and -xylon meaning wood. As you see, both the genus and species names make clear the subject of this rotter's desires.

Some people refer to this species as Carbon Antlers, and this seems just as apt as Candlesnuff Fungus - the latter being the common name promoted in the British Mycological Society's list of English Names of Fungi. Another name that you may see assigned to Xylaria hypoxylon in some older field guides is Stag's Horn Fungus, which could cause confusion with a similarly-shaped basidiomycete species Calocera viscosa, commony known as Yellow Stagshorn.

Identification guide

Close-up of Xylaria hypoxylon

Description

Small, upright stroma (the whitish interior of complex fruitbodies of ascomycete fungi) 2 to 8mm in diameter at the base and typically 3 to 5cm tall, usually in masses. Some are simple spikes, but most branch like antlers. Initially black and finely downy near the sterile base and white with conidia (asexual spores) towards the tips, the whole of the fruitbody eventually blackens as the ascospores ripen within asci that develop within flask-like perithecia embedded in the surface. (The tiny bumps with minute holes on the outer surface of the upper section of fruitbodies coincide with the locations of perithecia.)

 

Spores

Bean shaped, smooth, 11-15 x 4-6µm.

Spore print

Black.

Asci

Typically 140 - 220 x 8µm, with eight spores per ascus.

Odour/taste

Not distinctive.

Habitat & Ecological role

Saprobic, on fallen branches and rotting stumps of broad-leaf trees; very occasionally on pine stumps. Candlesnuff Fungus specialises in consuming neither the softish cellulose nor the much tougher lignin but rather the polysaccharides - glucan and other minority content compounds of timber that bind the cellulose and lignin together to form what we recognise as wood. As a result, when these and various other ascomycetous fungi have consumed what they can of a dead stump the remainder is a nutrient-rich soft mess that insects and other small creatures are able to feed upon (if other cellulose- or lignin-rotting fungi haven't found it first).

Season

Throughout the year, but producing ascospores in autumn and early winter, at which times the whole fruitbody turns black.

Similar species

Xylaria carpophyla is similar but much more slender; it grows on rotting beach mast and is often buried in leaf litter.

Acknowledgements

Some of the pictures on this page are shown with the kind permission of David Kelly.

Xylaria hypoxylon on a dead stump

Reference Sources

Fascinated by Fungi, Pat O'Reilly 2016.

Molecular and morphological evidence for the delimitation of Xylaria hypoxylon Derek Peršoh1, Martina Melcher and Katrin Graf, Mycologia, March/April 2009 vol. 101 no. 2 pp256-268.

Dennis, R.W.G. (1981). British Ascomycetes; Lubrecht & Cramer; ISBN: 3768205525.

Breitenbach, J. & Kränzlin, F. (1984). Fungi of Switzerland. Volume 1: Ascomycetes. Verlag Mykologia: Luzern, Switzerland.

Medardi, G. (2006). Ascomiceti d'Italia. Centro Studi Micologici: Trento.

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

Top of page...


Fascinated by Fungi, 2nd edn, hardback

If you have found this information helpful, we are sure you would also find our book Fascinated by Fungi by Pat O'Reilly very useful. Author-signed hardback copies at a special discount price are available here...

Other nature books from First Nature...