Gilled Polypore

The Gilled Polypore Trametes betulina (Fr. Lenzite du bouleau) is rather an anomaly. It has recently been put in the genus Trametes. From above it looks like a Trametes, but underneath it has gills. No other Trametes species has gills, they have pores, and jolly handy it is for distinguishing Trametes bracket fungi from other similar genera, such as Stereum (which have smooth somewhat velvety undersides). Rather sadly the 'approved' English name has also been changed to the prosaic 'Gilled Polypore' from the romantic 'Birch Mazegill'.

The upper side is usually pale (white, cream and/or grey) but they can be brown, orange or red too. There can also be green from algae growing on the surface. The individual brackets are between 2 and 10 centimetres across and 2-3 centimetres deep. Growing directly from trunks or branches the fruiting body can usually only develop into a sort of half moon, not a full round. There are visible growth bands and quite a bit of somewhat bristly fuzz. The outer edge is rounded, not a contrasting colour and sometimes lobed. The brackets are quite thin, just a few millimetres. 

Underneath there are pale brown crowded irregular gills, with creamy white spores. The brackets are leathery, with white flesh if cut in half. 

This species is most often found on Birch, either living or dead, but it can also grow on Oak and Beech, and sometimes Alder and Hazel. It usually grows in groups, but can be a single isolated bracket. It is uncommon, but also possibly often disregarded because on first appearance it just looks like an old faded Turkey-tail T. versicolor, which is very abundant. If you don't turn it over, or identify the wood it is growing on as Birch, you will misidentify it.

The species is one of those which causes white rot. It is not toxic, but not worth eating.