Tricholoma album

The species was originally described as Agaricus albus by Jacob Christian Schäffer in 1774,^[2] and reclassified as Gyrophila alba by mycologist Lucien Quélet in 1886.^[3] It was given its current binomial name by German Paul Kummer in 1871.^[4] The British Mycological Society has listed "white knight" as its common name.^[5] The generic name derives from the Greek trichos/τριχος 'hair' and loma/λωμα 'hem', 'fringe' or 'border', while the specific epithet is the Latin adjective albus "white".^[6]

The fungus is classified in the section Lasciva of the genus Tricholoma, characterised by species with a strong odor and acrid or bitter taste;^[7] an older classification has it placed in section Inamoena.^[8]

Marcel Bon named the variety Tricholoma album var. thalliophilum to account for those mushrooms that differed by staining blue-green with thallium oxide and sulfoformol;^[9] in the absence of additional differentiating characters, some later authors have questioned the taxonomical value of this characteristic.^[10]

The cap is 3–7.5 cm (1.2–3.0 in) wide and white with a pale yellow tinge, and more yellow or ochre in the centre as the fruit body ages. Convex with a slight boss, the cap is broadly conical in shape with inrolled margins. The white to pale yellow or ochre-tinged stipe is 3–8.5 cm (1.2–3.3 in) high and 0.8–1.5 cm wide and has no ring. There is no ring or volva. The mushroom has a prominent unpleasant sweet smell reminiscent of honey and radishes, and has an acrid and disagreeable taste.^[1] The thick gills are widely spaced with finely serrated edges. The spore print is white, the oval or oblong spores 5–7 μm long by 3.5–5 μm wide.^[7]