Mushroom of the Month - February 2009

Few of the Ascomycota produce large fruitbodies, but Xylaria polymorpha, commonly called Dead Man's Fingers, certainly does. Its morbid eruptions appear throughout the year at the base of beech and ash stumps (and occasionally on other buried hardwoods). Few fungi have more appropriate common names: imagine the shock of walking through a tree-lined churchyard at dusk and seeing a set of blackened fingers apparently clawing their way out of the ground!

Slice through one of the fingers and you find that, surprisingly, the material inside is white with little black flasks just beneath the surface layer. This is where the spores develop inside what are termed ascii, and when ripe the spores are released to drift on the breeze. (It takes very little breeze to carry the minute spores quite a long way.)

Xylaria belong to a group of burnt-looking fungi knows as the Pyromycetes (the name itself being a reference to fire). There are many other Xylaria, including the very common candle-snuff fungus Xylaria hypoxylon - yet another of the woodland fungi that you can see in the winter months.

Many of the Pyromycetes produce very small fruitbodies that almost invariably go unnoticed, but another year-round species, Daldinia concentrica, is very conspicuous; its most commonly used common name in the UK is King Alfred's cakes, but you may find people referring to 'cramp balls' - the connotation being that if you carry these hard black hemispherical fungi in your pocket you will not suffer from cramp. These 'tough cookies' grow mainly on the dead trunks and large branches of ash trees, whether standing or fallen.

All I can say is that I do not kepp my pockets filled with these fungi, and I do (albeit very occasionally) get attacks of cramp. So does that prove anything?