Tricholoma equestre
Description
Tricholoma equestre can be recognized through a combination of features. It has the white spore print, notched gills, medium stature, and other features that define the genus Tricholoma; it lacks a partial veil, which means there is no ring on the stem; it grows under pines in poor, sandy soil; it has a yellow cap that becomes brownish with age and lacks blackish appressed fibrils; its odor and taste are mealy; and, finally, its gills are yellow.
Tricholoma equestre (hereinafter – T. equestre) is a common edible mushroom that is considered to be toxic under certain conditions.
Reported four cases of acute poisoning caused by T. equestre, including one lethal outcome in Lithuania between 2004 and 2013. In severe case, fatigue, nausea without vomiting and muscle pain, profuse sweating without fever, and respiratory insufficiency occurred. Laboratory tests showed an elevation of creatine kinase (CK), aspartate aminotransferase (AST), and alanine aminotransferase (ALT). Although clinical findings and laboratory tests support evidence of rhabdomyolysis, no renal insufficiency was observed. Significance of T. equestre in cardiac changes is feasible but remains unclear.
Common names: Man On Horseback, Yellow Knight, Grünling (German), Gąska Zielonka (Poland), Canari (France).
Mushroom Identification
Ecology
Mycorrhizal with pines; growing alone, scattered, or gregariously in poor, sandy soil; summer and fall; widely distributed in North America as a species group.
Cap
5–10 cm across; convex becoming broadly convex; sticky when fresh, but soon dry; bright greenish-yellow when young and fresh, but soon developing a brown center that expands nearly to the margin with age; bald or with a few appressed fibers over the center (but not prominently overlaid with blackish radiating fibers).
Gills
Attached to the stem through a notch; close; short-gills frequent; pale to bright yellow.
Stem
5–7 cm long; 1.5–2.5 cm thick; more or less equal, or with an enlarged base; bald or finely hairy to subscaly; pale yellow or whitish near the apex, more yellow below; basal mycelium white.
Flesh
White; not changing when sliced.
Odor and Taste
Mealy.
Spore Print
White.
Microscopic Features
Spores 5–7 x 3–4 µm; ellipsoid; smooth; hyaline in KOH; inamyloid. Basidia 4-sterigmate. Lamellar trama parallel. Hymenial cystidia not found. Pileipellis an ixocutis; elements 2.5–5 µm wide, smooth, hyaline to reddish in KOH. Clamp connections not found.
History
Carl Linnaeus described this striking mushroom in the second volume of his Species Plantarum of 1753, wherein he named it Agaricus equestris.
It was the German mycologist Paul Kummer who, in 1871, transferred this species to the genus Tricholoma, thus creating its current binomial Tricholoma equestre.
Synonyms of Tricholoma equestre include Agaricus equestre L., Agaricus auratus Paulet, Agaricus flavovirens Pers.,Tricholoma equestre var. equestre (L.) P. Kumm.,Tricholoma auratum (Paulet) Gillet, and Tricholoma flavovirens (Pers.) S. Lundell.
Tricholoma was established as a genus by the great Swedish mycologist Elias Magnus Fries. The generic name comes from Greek words meaning 'hairy fringe', and it must be one of the least appropriate mycological genus names because very few species within this genus have hairy or even shaggily scaly cap margins that would justify the descriptive term.
As a specific epithet the term equestre is not quite so difficult to unscramble; it is to do with horse riding.
Video
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