Sunday, August 1, 2010

Mushroom of the Month - August 2010


Marasmius oreades, the Fairy Ring Champignon, is a small, pale-brown mushroom that is particularly common in the Autumn. You find these edible fungi on garden lawns, in graveyards, on parkland and most other kinds of short grassland that is not heavily dosed with fertilisers or weedkillers. This year, due to a wet July here in the west of Britain, the fairies have been out dancing earlier than usual, and rings and groups of Fairy Ring Chanpignons are already plentiful.
There is a logical explanation for fairy rings (unfortunately!). It is expandings underground discs of mycellium that causes these ring formations - not necessarily the work of fairies, therefore - a circle in a grassy area marking the periphery of a buried fungal growth. The disc becomes an annulus once the mycellium has consumed all it can from the central area, and so the diameter of a ring is an indication of the age of the fungal organism that is causing it.

The most common types of fairy ring cause the turf to grow a darker green, but other types of fungi may cause the grass to turn yellow or reddish. The grass inside a ring may die back because the soil there has been depleted of organic material and resists watering. When two fairy rings meet they gebnerally cannot cross one another (because the nutrients needed by the mycellia have already been consumed) and so the rimgs break and become arcs. Ring expansion is also broken when the perimeter comes up against a deeply-rooted tree, a wall or a deeply sunk concrete post etc. These grassland fungi don't always form rings, therefore, and in fact lines of the little brown mushrooms are rather more common than complete rings.
Up to 5 or 6cm tall and with a cap diameter of typically 2 to 4cm, this is one of the many mushrooms that change colour between dry and wet weather. Caps are usually pale beige when dry, turning rather darker when wet. Often the edges of the caps are shallowly scalloped, while the main gills are widely spaced and just free of the stems, and they are interspersed with shorter intermediate gills.

Although quite small, this is a good edible mushroom, and it's very easy to gather enough for a meals small because they fruit in such great numbers. Discard the tough stalks and dry the caps on a radiator, in an open warm oven, or threaded on twine and hung up in a warm dry place (an airing cupboard will do, provided it is well ventilated. Stored in jars, dried mushrooms can be kept for as long as you like.

The family Marasmiaceae (within the order Agaricales) are white-spored fungi, many of which are able to survive drought and near desiccation and can later recover when it rains. Another edible mushroom within this family is the Shiitake mushroom, Lentinula edodes.
Of course, it's impossible to prove a negative, and just because we have a scientific explanation for fairy rings of mushrooms doesn't mean that fairies do not exist. They may even have the power to determine where fungal spores can meet, mate and make rings. Who knows?

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