Turkey Tail Tales...

I found these fine specimens of the fungus commonly known as turkey tail (Trametes [Coriolus] versicolor) along the Raisby Way disused railway line near Durham this afternoon. If you have a vivid imagination those concentric strips of colour resemble the bands of colour in a turkey's tail. 

It's a very common bracket fungus that has excited a lot of scientific interest in recent years, for several reasons. It has long been used in China to make traditional medicinal infusions and research over the last few years has identified components in the fungus that have promising anti-cancer activity. Also, the fungal mycelium that proliferates in dead wood, causing white rot, secretes powerful enzymes that break down woody tissue and may have value in biofuel production from wood waste, as well as in breaking down industrial pollutants. Not just a pretty toadstool, then....

Birch Brackets

I found two typical bracket fungi that live on silver birches this afternoon, on some trees on the banks of the river Tyne near Wylam. This is the aptly named hoof fungus Fomes fomentarius. We tend to think of toadstools as here-today-gone-tomorrow organisms that appear overnight, shed their spores over a day or two and then wither away but bracket fungi like these are perennial, adding a new layer of spore- producing tissue (the hymenium) every season until the tree that they are digesting has yielded up all its available nutrients. During their long lifetime the brackets can produce millions of spores. Each successive layer of spore-producing tissue is marked on the surface of the bracket by a ring-like indentation, rather like the annual rings of a tree but visible on the fungal outer surface. The hymenium on the underside of this specimen, formed from thousands of pores lined with spores, shows signs of damage - probably from a slug.

These two are old specimens, are probably moribund - their hyphae have exhausted the supply of nutrients they can extract from their host's wood, which by this stage has developed a crumbly texture akin to balsa wood.

 This is an old specimen of the most familiar bracket fungus growing on birch, the birch polypore Piptoporus betulinus, also known as the razor strop fungus on account of its past use for honing a keen edge on cut-throat razors. Young specimens tend to be cream-coloured but they go brown and become leathery as they age. 

Bracket fungi like these are hosts to a variety of different insects that breed inside their tissues, so this is a food chain where plant tissue is being converted into fungal tissue which in turn is being transformed into animal tissue. If you harvest one of these old bracket fungi at this time of year and keep it in a container covered in muslin (which I've just done) you can expect to see a variety of different beetles emerge in spring and early summer - and if they do I'll post pictures of them when they appear.

Chicken-of-the-woods

This magnificent and still-expanding chicken-of-the-woods Laetiporus sulphureus is growing in a dead oak tree alongside Durham University Botanic Garden's woodland nature trail. So far it has only produced two tiers but there may well be more by the time it reaches maturity, with the largest up to 40cm. in diameter. The underside of each bracket is covered in countless tiny pores which will soon begin to shed spores. 

In this more conventional eye-level view you can see the yellow liquid that often exudes from this fungus. According to M.C. Cooke's British Fungi, published in 1884, and which I picked up in an antiquarian bookshop a while ago, 'as this fungus dries it becomes covered in beautiful crystals of oxalate of potash'. More interestingly, Cooke mentions that 'during decomposition this plant emits a bright phosphorescent light...' Now that is something I really must see: as darkness falls, spooky glowing lights in the woodland. The fungus will probably take two or three months to reach maturity and begin to decompose, just as autumn arrives.

The Afterlife of Trees

I think it might have been Oliver Rackham, botanist and noted expert on woodlands, who once commented that the only object in woodlands more valuable than a live tree was a dead one, since they host so many species of wood-boring beetles and other insects that breed in dead wood. This ancient beech stump, in Durham University Botanic Garden’s new woodland nature trail, is riddled with emergence holes from insects that have bred in it, but its most conspicuous features are the magnificent specimens of the bracket fungus (Ganoderma sp.) that was almost certainly the cause of its death. This parasitic fungus weakens the tree and infected trunks typically snap somewhere above head height during gales. The fungus is perennial, so each year the bracket develops a new zone of spore-producing tissue around its periphery and generates so many spores that they cover the vegetation below with what looks like a layer of cocoa powder. You can estimate the age of the bracket by counting the number of ‘steps’ on its upper surface; each marks the end of a year’s growth. During their ten years of existence, these brackets must have produced billions of spores. You can read more about the woodland nature trail at http://www.dur.ac.uk/botanic.garden/?itemno=7173