Attack of the parasitic jelly fungus

 

This gloopy-looking stuff is Yellow brain fungus Tremella aurantia, growing on the dead branch of a tree along one of my favourite walks, in the Deerness valley, County Durham. It’s a jelly fungus with a rather sinister lifestyle, parasitising another common fungus, hairy curtain crust Stereum hirsutum, which you can just see, dying, on the underside of the branch.

The microscopically-fine hyphae of the parasite, invisible to the unaided human eye, creep through the decaying wood, find and clamp onto those of their host and eventually kill it. The damp, foggy weather we’ve had recently has been perfect for the growth of the gelatinous parasite.

There are two common species of Tremella in the British fungal flora - this one and Tremella mesenterica - which are virtually identical and can only be easily identified by the hosts they parasitise: T. mesenterica preys on another crust fungus called Peniophora, which often grows on gorse stems hereabouts.

And here, a little further down the dead branch bearing the yellow brain fungus, is some more hairy curtain crust, so there’s plenty more of its victim for it to feed on.

Dead Assets

With all the doom and gloom about dying ash trees in the news, maybe it's as well to bear in mind the wise words of Oliver Rackham - probably Britain's foremost authority on trees and woodlands - who observed that "a huge dead tree is still beautiful, and as good a habitat as a living tree". When a tree dies a whole host of organisms colonise and feed on it throughout its afterlife, which can last for decades. The National Trust owns two woodlands on the south bank of the River Swale at Richmond in North Yorkshire - Billy Bank wood and Hudswell wood - and has taken great care to ensure that there's a plentiful supply of dead wood lying around to act as a habitat for organisms that depend on this habitat.

This massive fallen beech is covered by a carpet of moss on its upper surface while ...

.. the underside hosts numerous fine young examples of Ganoderma fungus. This bracket fungus can live on the dead wood for a decade or more, producing a new layer of white sporing tissue on its underside every year.

I think this is probably a sycamore stump, hosting one of the densest populations of candlesnuff fungus Xylaria hypoxylon that I've ever seen.

There are also some decaying hazels that must once have been coppiced. Their decaying poles are the favourite substrate for hairy curtain crust fungus Stereum hirsutum. This is a young specimen ....

.... and here's a more mature example.