Plant of the Week – 22nd February 2021 – The fungus without a name

Some people, when considering fungi, imagine the classic autumnal mushrooms & toadstools (a protective cap with gills suspended underneath, and supported on a stalk); they may even recall a bracket fungus protruding 90 degrees from the vertical trunk of a tree. But our environment is filled with fungi; not just in the woods and fields but along our streets, parks, and gardens. It is believed that for each species of plant there are several species of fungi although many of these are very small (termed microfungi) and unless you know what you’re looking for, they are easily overlooked. Eutypa maura is a perfect example and many of us will have walked past it without realising, yet once you appreciate the effect a number of individual Eutypa maura can have on wood, you’ll start to notice it.

Eutypa maura ‘ticks’ many boxes:

· It is common; most frequently associated with deadwood of the easily recognised sycamore (Acer pseudoplatanus).

· As sycamore is frequent within the urban environment (especially parks & recreational areas) so is the fungus.

· Despite being a microfungus, the combined effect of several individuals provides field recognition via a distinctive pattern on the wood surface.

· If fortunate, you’ll find visible signs that this fungus provides food for rodents.

· It produces interesting and intricate markings within the wood, good for woodcraft?

What follows will hopefully reveal what you’ve been missing.

Eutypa maura (syn. Eutypa acharii) is common and easy to find – locate a mature sycamore (Acer pseudoplatanus) where dead twigs and branches fall and remain on the ground (e.g. not in a well-manicured environment) such as a low maintenance area within a park or sports field; there is a good chance of a location near you. It’s not that the fungus grows only on fallen wood, it grows on dead wood still attached to the tree. It’s just easier for you to spot dead wood once it’s lying on the ground.

The fungus grows within dead decorticated wood and it blackens the surface with a very thin layer (termed a stroma). If an individual Eutypa maura has the wood to itself, the black stroma can be extensive, however, if many individual Eutypa maura colonise the wood, they do not merge together but instead only blacken their ‘patch’; they do not encroach into neighbouring patches. As the natural colour of the wood is usually pale, all these individuals create a wonderful patchwork on the surface; the territories of the Eutypa is clear for all to see. In the words of a fellow Edinburgh Mycologist, the pale lines are the ‘battle zones’ of the fungi.

But this demarcation is not just a superficial mosaic on the outer surface of the wood; it extends through the interior too. Cut transversely, and from the white demarcation lines seen on the outer surface, there follows a corresponding black line running into the centre; each individual Eutypa maura producing a layer of darkened hyphae to separate itself from its neighbour.

These black lines produce an additional, quite dramatic effect. Take a long piece of wood, covered with the black patches and white lines (as seen in the first photo, above) and whittle the outer layer to reveal the corresponding black lines of demarcation. Once revealed, smooth with sandpaper followed by a wipe with vegetable oil to give a dramatic finish. If the word spalting springs to mind, you’ll be right.

Whilst looking for Eutypa maura wood under sycamore you may be fortunate to find an unexpected twist to the hostilities, although this time involving the animal kingdom. The black layer of Eutypa maura may be very thin, however what the fungus is able to do is to breakdown the complex wood molecules, releasing valuable nutrients for building the stroma and reproductive structures and rodents take full advantage. Look closely at a large expanse of a black stromatic Eutypa maura and you find strange paired gouges, the result of repeated scraping off of the stroma with rodent incisors. The damage can be extensive, indicating that these rodents have probably spent considerable time eating the fungus. Dead branches still attached to the tree, a metre or two above the ground are not safe from the attentions of these mammals either. The damage however is not permanent and the Eutypa can regrow.

A mature Eutypa maura will produce tiny black spheres (perithecia) immersed within the wood, each perithecia connected to the outside world via a very short neck. Within these spheres, tiny curved spores are produced which, when mature, are ejected through the short neck for dispersal on air currents.

So where does the title of this article come from? Eutypa maura has no common name in the UK, however, as is often the case, the Europeans can provide a solution. In Germany, this fungus may be referred to as giraffenhals-holz and when translated into English is as appropriate a name as could be wished for.

References

Ellis, M. B. and Ellis, J. P. Microfungi on Land Plants; An Identification Handbook. Enlarged Edition. The Richmond Publishing Co. Ltd. 1997

Kendrick, Bryce. The Fifth Kingdom Fourth Edition. Indianapolis. Hackett Publishing. 2017.

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