Chicken of the woods

Don’t count your Chickens of the woods before they grow, and don’t ignore them when they don’t show.

The large, fresh yellow, annual fruitbodies of Laetiporus sulphureus are known as ‘Chicken of the woods’. They grow from May to autumn and are found on many broadleaved trees, but especially oak, in UK. I suppose the name arises from people wandering through woods and spotting a yellow lump in a branch fork, seemingly with wings. ‘Look! There’s a chicken’ they wound presumably cry.

You can often find them growing out of old wounds on the trunk or main branches of a tree, but they can grow near the ground too. I’ve seen a bright yellow one on a plum stump and an old, white one at the base of a wild cherry. The overlapping, fleshy fans can reach up to around 1m across but they do get eaten so older ones may look a bit dog-eared.

The bright yellow colour fades over the growing season and the fungus looks white and chalky when it is old. The disease can be in a tree for decades and the fruitbodies don’t appear every year, which is typical of the unhelpfulness of fungi.

The fungus causes a brown rot in the wood of a tree by eating the pale cellulose and leaving the darker lignin. Eventually the wood degenerates into brown or reddish cubes and often you can see a white mycelium, like a skin connecting them.

The disease can be a health and safety issue if the tree is close to lots of people as it is difficult for the tree to adapt to the loss of cellulose, which provides the flexibility of the wood. Trunk or branch can, then, become brittle and weak. So, if you see this fungus on a tree but then it doesn’t appear the next year that doesn’t mean it has gone away. It’s still there, munching on the cellulose – you’ll see it again sometime.

This can be a spectacular fungus and, when young, it is supposed to be edible, though I haven’t tried it myself.

Young fruitbody on oak

Mature fungus and brown rot of oak

Old fruitbody on robinia

Phaeolus schweinitzii

Phaeolus schweinitzii is a serious fungal disease of most conifer trees. It usually enters the tree via root tips and weakens the roots as it utilises the cellulose in the wood for food. It can reach right up to the base of the tree and even into the lower trunk. I have found Pheaolus high up in trees, but only rarely.

Young, yellow fruitbody





Mature brackets near base of Douglas fir.



The fungal fruitbody starts off as a formless yellow lump, growing out of the ground near a tree or else from its base or maybe from a wound on the stem. The bright, sulphur yellow colour is quite distinctive and shows that the bracket is actively expanding. These are found from May to August but older ones can last longer where they are protected from the weather. Once fully grown the yellow colour gives way to a rich brown and the top of the bracket is stiffly felty. Old fruitbodies are dull, grey or black and look very uninviting. The brackets can get up to nearly 1m in diameter but I usually see them less than half this size.

The disease is very serious and when the brackets appear it usually means that the decay is quite extensive. Trees with Phaeolus are liable to windthrow (because the roots lose their strength) or breakage on the lower trunk (because the centre of the base is so decayed that there is not enough healthy wood to deal with the stresses of the wind). It is very difficult to quantify the loss of root strength and so the appearance of the fruitbodies is a major safety issue.

Old brackets gradually disintegrate.

I'm back with news of a tree book

I've not blogged for a while. It's a good job nobody's been holding their breath waiting.
My news is that I have written a book called Urban Trees, a practical management guide. It's about trees and the development of urban areas from a UK perspective.  The publisher is Crowood Press and I expect it to be published in the autumn, 2011.