What You Should Know
Tricholoma sulphureum is an inedible or mildly poisonous mushroom found in woodlands in Europe. It has a distinctive bright yellow color and an unusual smell likened to coal gas. It occurs in deciduous woodlands in Europe from spring to autumn.
Other names: Sulphur Knight, The Stinker, Sulfur Trich, Gas Agaric.
Tricholoma sulphureum Mushroom Identification
Sulfur yellow, often with reddish-brown or olive tints; convex, usually with a wavy margin, sometimes flattening or becoming slightly depressed, but retaining an umbo; matt; 3 to 8cm across.
Bright sulfur yellow; broad; distant; sinuate (notched near the stem).
Yellow, lined vertically with sparse reddish fibers; cylindrical; 3 to 5cm long, 0.6 to 1cm dia.; no ring.
Ellipsoidal, smooth, with a pronounced attachment peg (known as a hilar appendage); 9-12 x 5-6.5μm; inamyloid.
Odor and Taste
A very strong odor of coal gas - so strong that you won't want to have it near enough to do a nibble test!
Habitat & Ecological Role
Ectomycorrhizal with deciduous broadleaf trees - mainly oaks and Beech - and just occasionally found also in coniferous woodland.
Although the main fruiting season is late summer and autumn, Sulphur Knights can appear in Britain and Ireland as early as the end of springtime.
Tricholoma equestre, mainly a northern species in Britain, has a yellow cap with a brown-olive central area; it has no significant odor.
Tricholoma sulphureum Taxonomy and Etymology
This mushroom was described scientifically in 1784 by French mycologist Jean Baptiste Francois (Pierre) Bulliard, who named it Agaricus suphureus, its currently-accepted binomial name Tricholoma sulphureum did not come into existence until 1871 when German mycologist Paul Kummer transferred this species to its present genus.
Tricholoma sulphureum has a number of synonyms including Agaricus sulphureus Bull., Gymnopus sulphureus (Bull.) Gray, and Tricholoma sulphureum (Bull.) P. Kumm.
Two very rare varieties of the Sulphur Knight are found, mainly in southern Europe. They are Tricholoma sulphureum var. hemisulphureum Kühner, which is also known by its common synonym Tricholoma hemisulphureum (Kühner) A. Riva; and Tricholoma sulphureum var. pallidum Bon. The autonomous form is therefore referred to formally as Tricholoma sulphureum var. sulphureum (Bull.) P. Kumm.
Tricholoma was established as a mushroom genus by the great Swedish mycologist Elias Magnus Fries. The generic name Tricholoma 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.
The specific epithet sulphureum is a reference to the color (sulphur yellow) of these mushrooms and is quite appropriate for their odor, too, which is similar to that of coal gas. Coal contains small amounts of sulphur, and so foul-smelling sulphur dioxide is produced when it burns.
Photo 1 - Author: Holger Krisp (Creative Commons Attribution 3.0 Unported)
Photo 2 - Author: Dominicus Johannes Bergsma (Creative Commons Attribution-Share Alike 4.0 International)
Photo 3 - Author: Andreas Kunze (Creative Commons Attribution-Share Alike 3.0 Unported)
Photo 4 - Author: Michel Langeveld (Creative Commons Attribution-Share Alike 4.0 International)