Tricholoma pardinum

The German naturalist Jacob Christian Schäffer published Fungorum qui in Bavaria et Palatinatu circa Ratisbonam nascuntur Icones in 1762, referring to its mottled or spotted cap. Common names include striped tricholoma, spotted tricholoma, tiger tricholoma, poison trich, leopard knight, and tigertop. Dirty trich was a name coined by author Gary H. Lincoff in response to a publisher's request for a more accessible name than its binomial one for North American guidebooks. Two subspecies have been described from southern Europe. ==Description==

The fruit body is a medium-sized mushroom, with a cap ranging from in diameter. The cap is initially hemispherical before flattening with maturity, and has a broad, shallow umbo. The cap margin is initially curled inwards but uncurls as it matures. The cap surface is silvery-grey and covered with concentrically patterned darker grey, brown or blackish scales that grow paler toward the cap margin, Secretan noting its resemblance to the cap of Sarcodon imbricatus. The gills are free (unattached to the stalk), white and thick, may have a yellow or greenish tint, and may drip water, as may the top of the stalk when broken. With age, the gill edges can become jagged and rough. The gill spacing is rather variable, ranging from distant to crowded; typically, between 100–120 gills extend fully from the stalk to the edge of the cap, with a variable number of lamellulae (shorter gills not extending fully from stalk to cap margin). The stout stalk may be white, pale grey or pale brown, and is thicker at the base. The texture of the stalk surface ranges from fibrillose (appearing to be made of coarse fibres arranged longitudinally) to more or less smooth, and the stalk base will stain dirty brown to yellow when bruised. It is high and wide, with the base in diameter, and bruises a dirty yellow. There is no ring or volva. The flesh is whitish and has a pleasant mealy smell and taste. Variety filamentosum has a mealy odour and taste reminiscent of cucumber. The spore print is white, and the oval to oblong spores are 7.5–9.5 μm long by 5.0–7.0 μm wide. Spores are smooth, hyaline (translucent), nonamyloid, and have a prominent hilum. The basidia (spore-bearing cells) are cylindrical to club shaped, four spored, and measure 39–50 by 8.0–9.6 μm. The cystidia present on the gill edge (cheilocystidia) are thin walled, hyaline, have a short stalk and a spherical apical portion, and measure 29–41 by 12–21 μm; cystidia are absent from the gill face. The cap cuticle ranges in cellular form from a cutis (in which the hyphae are bent over, running parallel to the cap surface) to a trichoderm (with hyphae emerging roughly parallel, like hairs, perpendicular to the cap surface); the hyphae comprising the cuticle are cylindrical, and measure 2.0–9.0 μm wide with a club-shaped tip up to 11 μm wide. Similar species Tricholoma pardinum mushrooms may be confused with several edible grey-capped members of the genus Tricholoma, and some authorities recommend leaving all grey-capped Tricholoma mushrooms for experienced hunters. There are several superficially similar European species that could be mistaken for T. pardinum. The smaller T. terreum lacks a mealy smell and cap scales, is darker and less robust, and has smaller spores measuring 5.0–7.5 by 4.0–5.0 μm. The edible T. argyraceum somewhat resembles T. pardinum—but with finer scales, and gills and bruised parts that yellow with age. Unlike the preferentially montane T. pardinum, these lookalikes tend to fruit at lower elevations. T. atrosquamosum is smaller and darker than T. pardinum, and has a peppery aroma. T. orirubens has fine dark scales and pinkish gills, brittle flesh, and is generally smaller. T. myomyces is smaller than T. pardinum, has a thin, fibrous partial veil on young specimens, and elliptical spores measuring 5.0–6.0 by 3.5–4.0 μm. The edible and highly regarded T. portentosum is of a similar size, though has a uniform grey cap that is never scaled. In North America, Tricholoma pardinum can be confused with T. nigrum and forms of T. virgatum that have more streaked rather than spotted caps. A form of T. pardinum in North America can be nearly white with pale scales, and may be confused with the whitish edible species T. resplendens. Microscopically, the presence of clamp connections sets T. pardinum apart from most other members of the genus; the similar-looking (though more tan-coloured) T. venenatum also has them. According to Alexander H. Smith, T. huronense is closely related, but can be distinguished from T. pardinum by its narrower gills, its tendency to form drops of reddish liquid on the gills and stalk, and an ash-grey and scaly stalk surface. T. atroviolaceum and T. imbricatum are also similar. ==Distribution and habitat==

Tricholoma pardinum is found across Europe, where it is more common in the south. It is abundant in the Jura Mountains in eastern France. The species is found in Belgium and Germany, but has not been recorded from the Netherlands or the British Isles. A historical record from Estonia has been discarded because no herbarium specimens could be found. In Asia, it has been recorded from İzmir Province in southwestern Turkey, China, and Sado Island in Japan. It is found widely across temperate North America, where Santa Cruz County and Sierra Nevada in central California in the west of the continent, and the central Appalachians in the east form the southern limits of its distribution. T. pardinum is commonly associated with conifers in the Rocky Mountains and Pacific Northwest, and with tanoak (Lithocarpus densiflorus) and madrone (Arbutus spp.) in California. The mushroom can be abundant in some years, especially warmer years with higher rainfall, yet missing or rare for several years in between. In Europe, it is found on chalky soil in woodland with beech and fir in summer and autumn, where it prefers areas of some elevation. Although it may be found in groups or fairy rings, it most commonly occurs singly. ==Toxicity==

Tricholoma pardinum is one of several poisonous members of the genus Tricholoma; its large size, fleshy appearance, and pleasant smell and taste add to the risk of its being accidentally consumed. It was responsible for more than twenty percent of cases of mushroom poisoning in Switzerland in the first half of the 20th century. appears to cause a sudden inflammation of the mucous membranes lining the stomach and intestines. Once gastric contents are emptied, metoclopramide may be used in cases of recurrent vomiting. ==See also==