Field mushroom  (Agaricus campestris)

A common, widespread species (3).

This widespread species is a close relative of the species of mushroom that is typically sold in shops (Agaricus bisporus) (3). The field mushroom has a creamy-white cap and stem, and bright pink or chocolate-brown coloured gills (2). The cap takes on a brownish tinge as it ages, and becomes more flattened in shape (3). Although edible, this species is easily confused with the deadly poisonous fungus the destroying angel (Amanita verna) when in the 'button' stage (3).

WARNING: Many species of fungus are poisonous or contain chemicals that can cause sickness. Never pick and eat any species of fungus that you cannot positively recognise or are unsure about. Some species are deadly poisonous and can cause death within a few hours if swallowed.

This cosmopolitan species has a wide distribution; it occurs in temperate parts of Europe, and is also known from Afghanistan, South Africa, Australia, China, northern India, Japan, southern Canada and the USA (3).

Occurs in manured pastures and meadows (3), and other grassy places (4). In Afghanistan it occurs in the desert in camel tracks after rain (3).

Fungi are neither plants nor animals but belong to their own kingdom. They are unable to produce their own food through the process of photosynthesis, as plants do; instead, they acquire nutrients from living or dead plants, animals, or other fungi, as animals do. In many larger fungi (lichens excepted) the only visible parts are the fruit bodies, which arise from a largely unseen network of threads called 'hyphae'. These hyphae permeate the fungus's food source, which may be soil, leaf litter, rotten wood, dung, and so on, depending on the species (4).

The field mushroom has been known since Greek and Roman times, and methods of cultivation were described in the seventeenth century (3). It is sold in northern India as a medicinal fungus. It grows in groups from August to November in Europe and from July to October in North America, and is particularly frequent after rain (3).

Although widespread, this species seems to be in decline (4). This may be related to the decline in horse populations in rural areas; in a belief dating back to Roman times, it was widely thought that this mushroom would only grow in areas frequented by stallions (3).

No conservation action has been targeted at this species.

For information on the conservation of fungi see Peter Marren's article 'waxcaps and woodland mushrooms' from Plant Talk on-line, available at:
http://www.plant-talk.org/stories/26fungi.html

• Fruit body: in fungi, the fruit body is the visible part of the fungus which bears spores (microscopic particles involved in both dispersal and reproduction).
• Photosynthesis: metabolic process characteristic of plants in which carbon dioxide is broken down, using energy from sunlight absorbed by the green pigment chlorophyll. Organic compounds are made and oxygen is given off as a by-product.

1. National Biodiversity Network Species Dictionary (Jan 2003): http://www.nhm.ac.uk/nbn/
2. Jordan, M. (1995) The encyclopedia of fungi of Britain and Europe. David and Charles, Devon.
3. Dickinson, C. and Lucas, J. (1979) The encyclopedia of mushrooms. Orbis Publishing, London.
4. Courteciusse, R. (1999) Mushrooms of Britain and Europe. Harper Collins Publishers, London.