Monsieur Gouny, our neighbour, looked at my small basket of mushrooms and he said ‘Ce sont les rosés?’ – they are the field mushrooms? – rosés des prés’ ? ‘Oh no they are not’, I replied in French. I illustrate some here as they were growing. They look like mushrooms but anyone who ate them would soon be writhing with a highly disturbed stomach.
I have many textbooks on mushrooms and toadstools and that on the mushrooms lists over seventy species. Of toadstools as a general group, there are thousands in Europe.
The mushrooms, collectively placed in the genus Agaricus all have spores which begin pink but which turn to a deep dark purple to black as they ripen. The so-called gills which carry the spores change colour as the spores change colour. Agaricus mushrooms all have a fleshy ring on the stem but the stem in otherwise bare and has no enveloping sac at its base (unlike the various deadly poisonous Amanitas).
The numerous true mushrooms all look very similar. So, how do you tell them apart?
Well the ones I collected make the answer very difficult.
These were Agaricus xanthodermus, the so-called ‘yellow-stainer’. I fear that almost all living things come in a variety of forms and the species of mushrooms are no exception. If you read the books they will tell you that the ‘yellow-stainer’ has two marked characteristics. Firstly, that the flesh in the base of the stem when cut, turns chrome-yellow, and that the broken flesh has a smell of ink. It so happens that mine have no smell at all, and the colour change is extremely slight.
I illustrate a specimen which is shows a little yellow in the base – good specimens would be brilliantly yellow.
So it is necessary to look for other signs which are less obvious. The shape of the cap helps. This is not a smooth even dome. When young it has a more rectangular section. The sides tend to be almost vertical and the top is more flat. [The one marked Y shows this shape.] Then if you cut the specimen in half, the young gills are exceedingly pale pink. Lastly look to where the mushrooms are growing. Agaricus xanthodermus does not normally, if ever, grow far away from trees, whilst the ‘rosé des prés’ is found in the open pastures. The yellow stainer is probably growing around the roots of the trees and in fact helping the tree to obtain minerals from the soil. It is also itself in return obtaining carbohydrates from the trees. So beware of mushrooms which look like mushrooms growing under trees! The field mushroom is obtaining nutrients from decomposing organic matter, possibly old horse dung.Above all remember that the best mushrooms have a red tinge to their flesh and will colour any water in which they are placed a pale pinky-red. The yellow stainer will never do that. All mushrooms can be placed either into the group of red stainers or the group of yellow stainers – which bruise yellowish,