Candlesnuff Fungus

Xylaria hypoxylon, or Candlesnuff fungus if you don't fancy trying to pronounce the scientific name, is a very widespread and common fungus in the UK and throughout mainland Europe, as well as in many parts of North America. It can be found all year round, but is particularly noticeable during late autumn and winter and is normally found on the dead wood of broad-leaved trees, and more rarely on coniferous trees. Candlesnuff fungus is usually one of the last fungi to attack rotting wood, and is often preceded by other species, such as Honey Fungus (Armillaria mellea and co.) and Sulphur Tuft (Hypholoma fasciculare).

Candlesnuff Fungus (Xylaria hypoxylon) on the UEA campus. The whole of
the stroma (fruiting body) turns completely black as
the ascospores (spores uniques to the ascomycetes fungi) ripen.

The fruiting body of Candlesnuff is between 3-5cm in height and some are simple spikes, but most tend to branch like antlers. They are black and velvety below, and whitish towards the tip and are usually found in clusters. The binomial name is derived from the fungi's habits, with the genus name Xylaria coming from a Greek noun that means wood and the species hypoxylon coming from hypo- which means beneath (or less than), and -xylon, also meaning wood.

Surprisingly (to me anyway!), there are a number of bioluminescent fungi in the UK, with Candlesnuff being one of them. The phosphorous that accumulates within the mycelium (the vegetative part of the fungus consisting of a mass of branching hyphae) reacts with oxygen and other chemicals within the fungus to emit a continual light. Unfortunately the bioluminescence is very weak so you can only see it in really dark conditions or using an image intensifier or by taking a long exposure photograph in a pitch black room. 

Candlesnuff Fungus (Xylaria hypoxylon) on rotting wood in NE Hampshire.

Further reading:

• First Nature: Xylaria hypoxylon