''Tricholoma terreum'', commonly known as the grey knight or dirty tricholoma, is a grey-capped

mushroom A mushroom or toadstool is the fleshy, spore-bearing fruiting body of a fungus, typically produced above ground, on soil, or on its food source. ''Toadstool'' generally denotes one poisonous to humans. The standard for the name "mushroom" is t ...

of the large genus ''

Tricholoma ''Tricholoma'' is a genus of fungus that contains many fairly fleshy white-spored gilled mushrooms which are found worldwide generally growing in woodlands. These are ectomycorrhizal fungi, existing in a symbiotic relationship with various spec ...

''. It is found in coniferous woodlands in Europe, and has also been encountered under introduced pine trees in

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

. It is regarded as

edible An edible item is any item that is safe for humans to eat. "Edible" is differentiated from "eatable" because it does not indicate how an item tastes, only whether it is fit to be eaten. Nonpoisonous items found in nature – such as some mushroo ...

. A 2014 article speculated that it may be poisonous,Heping Xia
Fatal toxins found in 'edible' wild mushrooms
in: Chemistry World, 16 June 2014 but Sitta ''et al.'' in 2016 published in the same journal a counter article demonstrating the unfounded nature of such speculation.

Taxonomy

The fungus was originally described as ''Agaricus terreus'' by

Jacob Christian Schäffer Jacob Christian Schäffer, alternatively Jakob, (31 May 1718 – 5 January 1790) was a German dean, professor, botanist, mycologist, entomologist, ornithologist and inventor. Biography From 1736 to 1738 he studied Theology at the University of ...

in 1762, and as ''Agaricus myomyces'' by mycologist

Christian Hendrik Persoon Christiaan Hendrik Persoon (1 February 1761 – 16 November 1836) was a German mycologist who made additions to Linnaeus' mushroom taxonomy. Early life Persoon was born in South Africa at the Cape of Good Hope, the third child of an imm ...

in 1794. It was given its current binomial name by German

Paul Kummer Paul Kummer (22 August 1834 – 6 December 1912) was a minister, teacher, and scientist in Zerbst, Germany, known chiefly for his contribution to mycological nomenclature. Earlier classification of agarics by pioneering fungal taxonomist Elias Ma ...

in 1871. It is commonly known as the grey knight from its discoloured gills. Almost all modern sources consider '' Tricholoma myomyces'' to be a

synonym A synonym is a word, morpheme, or phrase that means exactly or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are all ...

of ''T. terreum'', but there are some exceptions. Bon mentions that ''T. myomyces'' has been defined for lowland mushrooms with white gills and a fleecy cap and Courtecuisse separates it on the same basis. Moser distinguished ''T. myomyces'' on the basis that the gills should go yellow.

Description

The

cap A cap is a flat headgear, usually with a visor. Caps have crowns that fit very close to the head. They made their first appearance as early as 3200 BC. Caps typically have a visor, or no brim at all. They are popular in casual and informal se ...

is wide and evenly covered in fine grey scales. Convex with a slight boss, it is broadly conical in shape. The whitish stipe is high and wide and has no ring. There is no ring or volva. The whitish

flesh Flesh is any aggregation of soft tissues of an organism. Various multicellular organisms have soft tissues that may be called "flesh". In mammals, including humans, ''flesh'' encompasses muscle Skeletal muscles (commonly referred to as mu ...

is thin, easily broken, and has a pleasant mild (not mealy) smell and taste. The widely spaced and uneven

gills A gill () is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they are ...

are free (unattached to the stipe). The

spore print 300px, Making a spore print of the mushroom ''Volvariella volvacea'' shown in composite: (photo lower half) mushroom cap laid on white and dark paper; (photo upper half) cap removed after 24 hours showing pinkish-tan spore print. A 3.5-centimeter ...

is white, the oval spores 6–7 μm long by 3.5–4.4 μm wide. It could be confused with the larger (and poisonous) '' T. pardinum'' has a mealy smell and cap scales; the edible '' T. orirubens'' has fine dark scales and pinkish gills.

Distribution and habitat

''Tricholoma terreum'' is found in Europe, where fruiting bodies appear under conifers, particularly pine and spruce, from late summer to late autumn. They may also arise in parks near these trees, and grow in

fairy ring A fairy ring, also known as fairy circle, elf circle, elf ring or pixie ring, is a naturally occurring ring or arc of mushrooms. They are found mainly in forested areas, but also appear in grasslands or rangelands. Fairy rings are detectable by ...

s. They are generally in quite densely populated groups though not bunched. It has been recorded growing under exotic ''

Pinus radiata ''Pinus radiata'' ( syn. ''Pinus insignis''), the Monterey pine, insignis pine or radiata pine, is a species of pine native to the Central Coast of California and Mexico (Guadalupe Island and Cedros island). It is an evergreen conifer in the fa ...

'' plantations in Australia.

Edibility

With a mild taste, the species used to be regarded as a good edible. It is seen in markets in France, along with ''

Clitocybe nebularis ''Clitocybe nebularis'' or ''Lepista nebularis'', commonly known as the clouded agaric or cloud funnel, is an abundant gilled fungus which appears both in conifer-dominated forests and broad-leaved woodland in Europe and North America. Appearin ...

'' and '' Tricholoma portentosum''. However, some authorities recommend that inexperienced pickers avoid all grey tricholomas. Recent chemical tests show that this species may contain toxins which can cause

rhabdomyolysis Rhabdomyolysis (also called rhabdo) is a condition in which damaged skeletal muscle breaks down rapidly. Symptoms may include muscle pains, weakness, vomiting, and confusion. There may be tea-colored urine or an irregular heartbeat. Some of th ...

. However, from more recent investigations it has emerged that only an abnormal quantity of Tricholoma mushrooms may trigger the rhabdomyolysis and normal consumption of about 200g of mushroom is safe unless there is an individual reaction.Piotr Rzymski, Piotr Klimaszyk
Is the Yellow Knight Mushroom Edible or Not? A Systematic Review and Critical Viewpoints on the Toxicity of ''Tricholoma equestre''
Wiley online library, first published: 25 July 2018, doi:10.1111/1541-4337.12374

References

{{Taxonbar, from=Q27266 terreum Edible fungi Fungi described in 1774 Fungi found in fairy rings Fungi of Europe Taxa named by Jacob Christian Schäffer

Taxonomy

Description

Distribution and habitat

Edibility

See also

References