Agaricus bitorquis is an edible white mushroom of the genus Agaricus

Agaricus

Agaricus is a large and important genus of mushrooms containing both edible and poisonous species, with possibly over 300 members worldwide...

, similar to the common button mushroom that is sold commercially. The name supersedes Agaricus rodmani. It is also commonly known as torq, the banded agaric, spring agaric, or pavement mushroom, as it has been recorded pushing up paving slabs.

Taxonomy

The specific epithet bitorquis is Latin

Latin

Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...

 "having two collars", and refers to the two rings resulting from detachment of the annulus from both the top and bottom of the stipe.

Description

The cap

Pileus (mycology)

The pileus is the technical name for the cap, or cap-like part, of a basidiocarp or ascocarp that supports a spore-bearing surface, the hymenium. The hymenium may consist of lamellae, tubes, or teeth, on the underside of the pileus...

 is dry, smooth, and white (but staining yellowish in age), and measures 4 to 15 cm in diameter, convex to flat; often with dirt on the cap.
The gills are free, very narrow, close, light pink color when young, becoming dark reddish-brown as the spores mature. The spore print

Spore print

thumb|300px|right|Making a spore print of the mushroom Volvariella volvacea shown in composite: mushroom cap laid on white and dark paper; cap removed after 24 hours showing pinkish-tan spore print...

 is chocolate brown. The stipe is 3 – 11 cm long, 2 – 4 cm thick, cylindrical to clavate (club-shaped), equal to enlarged at the base, stout, white, smooth, with a membranous veil and thick white mycelial sheathing near the base. The flesh is solid and firm, with a mild odor. It is often confused with Agaricus bernardii

Agaricus bernardii

Agaricus bernardii,commonly called Salt-Loving Agaricus is a mushroom in the Agaricaceae family of fungi. It partially resembles Agaricus bitorquis but it differs from that fungus by the reddish-brown staining of cap and stipe tissue as well as its briny odour...

; however, that mushroom has a salty odor.

Microscopic details

Basidiospores are elliptical in shape, smooth, and with dimensions of 5–7 x 4–5.5 µm

Micrometre

A micrometer , is by definition 1×10-6 of a meter .In plain English, it means one-millionth of a meter . Its unit symbol in the International System of Units is μm...

. Basidia are 20–25 x 6.5–8.5 µm, usually 4-spored, but often with 2-spored basidia present. The cystidia are present and numerous.

Distribution and habitat

A. bitorquis may be found growing solitary or in small groups in gardens, and at roadsides, often where salt is applied to combat ice in winter. Pushing through asphalt and slabs, it is very subterranean, and often matures underground. It is occasional throughout Europe

Europe

Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

 and North America

North America

North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

.

Edibility

A. bitorquis is a choice edible species, with a typical 'mushroomy' taste. Specimens collected in the wild may be gritty due to its often subterranean habitat. As with all specimens picked from the wild, care should be taken to consider the suitability of the collection site, as this species can bioaccumulate toxic heavy metals, especially lead, from polluted areas. Nutritional analysis has shown this species to contain 18 amino acids, including all of the essential

Essential amino acid

An essential amino acid or indispensable amino acid is an amino acid that cannot be synthesized de novo by the organism , and therefore must be supplied in the diet.-Essentiality vs. conditional essentiality in humans:...

 ones.

Cultivation

A. bitorquis, first cultivated commercially in 1968, has several growth characteristics that have piqued the interest of mushroom cultivators looking for an alternative to the standard button mushroom, A. bisporus. For example, A. bitorquis is more resistant to various viral diseases, can grow at higher temperatures and CO₂ concentrations, and has better resistance to bruising. Furthermore, high temperature-resistant strains have recently been developed which may help cultivators overcome problems associated with cooling production rooms during hot summer months.

External links

• Mushroom-Collecting.com - Agaricus bitorquis
• Index Fungorum listing of synonyms
• Roger's Mushrooms picture and description
• Mushroom Observer various photos
• (A Drawing by Julius Schaffer)