Yellow Stainer Agaricus xanthodermus
This poisonous mushroom is generally larger and more slender than common field mushrooms. The cap is creamy white, typically with a grey-brown centre. Another feature which makes this mushroom identifiable is the bright yellow colour which appears on the cap if the fungus gets bruised.
Conservation status in Norfolk
Not threatened
How to help
Please do not pick the fruiting bodies. These need to be allowed to produce and release their spores for reproduction.
Tony Leech
Information on the Yellow Stainer
How to recognise
The yellow stainer (or yellow-staining mushroom) is a true mushroom but unlike most of this group it is poisonous – so it is especially important to identify it correctly! It is generally larger (up to 12cm across) and more slender (up to 15cm tall) than a field mushroom. The cap is creamy white, often with a grey or brownish central area. The gills of a young specimen are pinkish but become dark-brown with age. It often occurs in quite large groups. The most distinctive feature of the yellow stainer is the appearance of a bright yellow colour immediately the cap of a fresh specimen is bruised (with the back of a finger nail) or the base of the stem is cut. Some other species of mushroom bruise a brassy yellow colour more slowly.
Where to see
The yellow stainer is widespread in Norfolk and occurs in grassy areas in such places as parks, churchyards and gardens. It is less common in woods but appears at NWT Lower Wood, Ashwellthorpe.
When to see
They can be seen late summer till autumn.
Did you know?
Its smell is distinctive and has been described as phenolic or like fountain pen ink.
Related questions
Can I eat the mushrooms which have appeared in my garden?
We would not advise it! They may look like Field Mushrooms (with pink, darkening to chocolate brown, gills and a ring (or ‘collar’) on the stem) but are more likely to be Yellow-staining Mushrooms which seem to have a particular liking for gardens and ‘marginal’ areas. Yellow Stainers tend to be more lanky than Field Mushrooms (more like Wood Mushrooms) and their caps are often streaked brown or grey. The diagnostic character is that when a young mushroom is bruised or cut (especially at the base of the stem) a bright yellow colour develops immediately. Note that both Horse and Wood Mushrooms bruise a dirty brassy yellow which usually takes a little time to develop. Both of the latter smell of aniseed when bruised but the Yellow Stainer has a harsher (inky or phenolic) smell which intensifies on cooking! Although some people seem able to eat Yellow Stainers without problem, most people exhibit moderate to severe gastric upset if they try. But they have probably never killed anyone!