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Lactarius torminosus

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Lactarius torminosus
Scientific classification
Kingdom:
Fungi
Division:
Basidiomycota
Class:
Agaricomycetes
Order:
Russulales
Family:
Russulaceae
Genus:
Lactarius
Species:
L. torminosus
Binomial name
Lactarius torminosus
(Schaeff.) Gray (1797)
Synonyms[1]

Agaricus torminosus Schaeff. (1774)
Lactarius necator (Bull.) Pers. (1800) Galorrheus torminosus (Schaeff.) P.Kumm. (1871)
Lactifluus torminosus (Schaeff.) Kuntze (1891)
Lactarius torminosus var. sublateritius Kühner & Romagn. (1954)

Lactarius torminosus
View the Mycomorphbox template that generates the following list
Gills on hymenium
Cap is depressed
Hymenium is decurrent
Stipe is bare
Spore print is yellow
Ecology is mycorrhizal
Edibility is edible but not recommended

Lactarius torminosus, commonly known as the woolly milkcap or the bearded milkcap, is a large basidiomycete fungus in the genus Lactarius. It is found in the United Kingdom, Northern Europe, and is common in North America, where it grows in mixed forests in a mycorrhizal association with various trees, most commonly birch. Although it is valued for its peppery flavour and eaten after pickling in Russia and Finland, it is highly irritating to the digestive system when eaten raw. The toxins responsible for the acrid taste are destroyed by cooking.

The fruit bodies produced by the fungus have caps which can reach up to 10 cm (3.9 in) in diameter. They are pink-flesh coloured, with whitish concentric zones. The edge of the cap is rolled inwards, and shaggy when young. On the underside of the caps are flesh-colored gills crowded closely together. It is on these fertile gill surfaces that the spore-bearing cells, the basidia are found. The cylindrical stem is a pale flesh colour with a delicately downy surface, reaching lengths of up to 8 cm (3.1 in). When cut or injured, the fruit bodies ooze a white latex that does not change colour upon exposure to air. The variety normandensis, in contrast, has latex that changes colour from white to yellow.

Taxonomy, classification, and phylogeny

The species was originally described scientifically by the German naturalist Jacob Christian Schäffer in 1774; he named it Agaricus torminosus.[2] Seven years later in 1781, Jean Bulliard named a species Agaricus necator and illustrated it in the first volume of his Herbier de la France.[3] This name, and its later name Lactarius necator (transferred to Lactarius in 1800 by Persoon[4]), are now considered synonymous with L. torminosus.[5] Other names that have been given to the species, and are now consider synonyms, include Lactarius necans (Gray, 1821),[6] Galorrheus torminosus (Kummer, 1871),[7] and Lactifluus torminosus (Kuntze, 1891).[8] The specific epithet torminosus means "tormenting" or "causing colic", and refers to the fact that it causes gastrointestinal distress.[9] It is commonly known as the "shaggy milkcap",[10] the "pink-fringed milkcap",[11] the "woolly milkcap" (alternatively spelled wooly), or the "bearded milkcap".[12]

Lactarius torminosus is classified in the subgenus Piperites, section Piperites (in which it is the type species), subsection Piperites of the genus Lactarius. Species in this subsection are characterised by having latex that does not turn yellow after exposure to air, and/or which do not stain the cut surface of the mushroom surface yellow.[13] A 2004 phylogenetic analysis of European Lactarius species concluded that L. torminosus fall into a well-supported group that includes L. torminosulus, and that these two species are phylogenetically close to a group that includes L. tesquorum, L. scoticus, and L. pubescens.[14]

Description

Detail of cap margin and gills

The cap is initially convex, but as it matures, the center of the cap forms a depression, and the outer edges become raised until eventually it assumes the shape of a shallow funnel; its width is typically between 2 and 12 cm (0.8 and 4.7 in). The margin (edge of the cap) is curled inwards, and when young is covered with a dense thicket of "hair" that withers in age to whitish fibers. Similarly, the cap surface is initially tomentose (covered with a thick matting of hairs) but eventually the hairs wear off, leaving the surface smooth. The surface is sticky to viscid and smooth on the central portion in early stages, often with whitish concentric zones. The overall cap color is pinkish-orange to pale dull pink, becoming orange to whitish on the margin, with the pink gradually fading. The white to flesh-colored flesh is firm, but becomes flaccid in age. The latex that is produced when the mushroom tissue in cut or injured is white to cream, and does not change color with prolonged exposure to air, nor does it stain the gills. It has an acrid taste, with a slight to pungent odor.[15]

The gills are short-decurrent (running a little ways down the length of the stem), close to crowded together, narrow, and are sometimes forked near the stem. Their colour is whitish, becoming pale vinaceous (the colour of red wine) to pale orange or cream tinged vinaceous, turning pale tan with age. The stem is 1.5–8 cm (0.6–3.1 in) long, 0.6–2 cm (0.2–0.8 in) thick, fragile, more or less equal in width throughout, cylindrical or narrowed at the base. The surface of the stem is dry, and either smooth to pruinose (with a very fine whitish powder on the surface). Its colour is pale light pinkish to yellowish tinged or slightly pinkish orange to orange white, sometimes spotted. The flesh of the stem is firm, beige white, and stuffed (as if filled with cotton), but it eventually becomes hollow.[15]

Microscopic characteristics

The spore print of L. torminosus is cream to pale yellow. The spores are 8–10.2 by 5.8–6.6 μm, roughly spherical to broadly elliptic in side view, and hyaline (translucent). The ornamentation on the surface of the spores is amyloid, partially reticulate, with interrupted ridges and a few isolated warts. The prominences are roughly 0.5–0.7 μm high, with a prominent apiculus. The basidia (spore-bearing cells) are 30–47.7 by 7.3–8.2 μm, four-spored, club-shaped to cylindrical, and hyaline. The pleurocystidia are only present in the form of macrocystidia (very long cystidia) embedded and originating in the hymenium and just below it, measuring 40.3–80.0 by 5.1–9.5 μm. The macrocystidia are abundant, spindle-shaped to ventricose (swollen on one side), gradually tapering in width, with granular hyaline contents. The cheilocystidia are 30–52 by 4.5–8.0 μm, also in the form of macrocystidia.[15]

Varieties

Lactarius normandensis was described by Alexander H. Smith in 1960 to account for the North American species closely resembling L. torminosus, but having instead latex which changed colour from white to yellow upon exposure, and which stained tissues and paper yellow.[16] Hesler and Smith reduced this taxon to the status of variety in 1979. Lactarius torminosus var. normandensis has been collected from Idaho, Michigan and Wisconsin in the United States, from Quebec in Canada, and from Switzerland. The variety resembles Lactarius pubescens var. betulae, but differs in its longer pleurocystidia, larger spores with slightly different spore ornamentation, and its strongly burning acrid taste.[17] The holotype specimen, collected by Smith near Nordman, Idaho in 1956, is kept in the fungus collection at the University of Michigan Herbarium.[18]

Edibility and toxicity

The intensely peppery taste of the raw mushroom can blister the tongue if sampled in sufficient quantity.[11] Some authors have reported the species as poisonous,[9][19] or causing "mild to fatal gastroenteritis".[20] In a 1930 publication, Hans Steidle reported that although the mushroom was not toxic to "unicellular and cold-blooded organisms", the liquid extract and the pressed juice of the fruit bodies, when injected under the skin of a frog, resulted in disturbed breathing, paralysis, and eventually death.[21] Despite these reports, in Finland, Russia and other North European countries it is eaten, after boiling or five-day soaking, pickled and valued for its hot, burning taste. In Norway it is roasted, and added to coffee.[12] The nutritive composition of the fruit bodies of Finnish specimens has been analysed and found to contain the following components (as a percentage of dry weight): protein, 17.2%; phosphorus, 0.46%; calcium, 0.12%; magnesium, 0.088%; potassium, 2.97%; sodium 0.011%.[22]

Similar species

Lactarius torminosulus is a dwarf version of L. torminosus, an arctic species associated with Betula nana or B. glandulosa.[23] Immature fruit bodies of L. scrobiculatus resemble L. torminosus, but they have a white latex that soon changes yellow upon exposure to air, and their stems have depressed shiny spots. The caps of the poorly known species L. cilicioides are zoned, and its spores are smaller. L. pubescens is physically quite similar, but can be distinguished by its paler colour and smaller spores (6–8.5 by 5–6.5  μm).[24] L. controversus has a cap margin that is not as hairy, whitish to cream-coloured gills, and larger spores measuring 7.5–10 by 6–7.5 μm.[25]

Ecology, distribution, and habitat

In Västerbotten, Sweden

Lactarius torminosus is a mycorrhizal species, and it plays an important role in nutrient and water uptake by trees. It grows in association with birch (Betula) and hemlock (Tsuga) in mixed forests. It is also known to grow in urban settings where birch trees are nearby.[15] Fruit bodies grow on the ground, scattered to grouped together. It is found throughout the United Kingdom, Northern Europe, and is common in North America, where it sometimes grows with aspen (Populus species).[12] The North American distribution extends north into the Yukon and Alaska,[26] and south to Mexico.[27]

The fruit bodies are a component of the diet of the red squirrel Sciurus vulgaris.[22] Lactarius torminosus mushrooms may be parasitized by the mold Hypomyces lithuanicus.[28]

Bioactive compounds

Lactarius torminosus contains the lactarane-type sesquiterpene lactone 15-hydroxyblennin A. This sesquiterpenoid has a lactarane skeleton, similar to compounds found in other Lactarius species, such as Lactarius deliciosus, Lactarius blennius (blennin A), and Lactarius rufus (lactarorufin N, deoxydihydroketolactarorufin N).[29] Fruit bodies contain a number of sterols, of which ergosterol is the predominant component at 60.5% (of total sterols), followed by the ergosterol derivatives ergost-7-en-3-ol (13.7%), ergosta-7-22-dien-3-ol (8.3%), and ergosta-5/7-dien-3-ol (17.0%).[30] The mushrooms also contain the compound velleral, a breakdown product of stearyl-velutinal, which is contained within the lactifers—specialized hyphal cells that produced the mushroom's latex. It has been suggested that broken lactifers leak precursors whose breakdown products act as defensive agents toxic to humans and effectively deter certain vertebrates that might consume the mushroom. Velleral, which has an extremely pungent taste and is thought to be responsible for the toxicity of the raw mushroom, is present at a concentration of 0.16 mg/g mushroom.[31]

See also

References

  1. ^ "Species synonymy: Lactarius torminosus (Schaeff.) Gray". Index Fungorum. CAB International. Retrieved 2010-07-12.
  2. ^ Schaeffer JC. (1774). Fungorum qui in Bavaria et Palatinatu Nascuntur Icones (in Latin and German). Vol. 4. Erlangen, Germany: Erlangae, Apud J.J. Palmium. p. 7.{{cite book}}: CS1 maint: unrecognized language (link)
  3. ^ Bulliard JBF. (1781). Herbier de la France. Vol. 1. pp. 1–48, plate 28. {{cite book}}: Unknown parameter |trans_title= ignored (|trans-title= suggested) (help)
  4. ^ Persoon Christian Hendrik (1799). Observationes mycologicae seu Descriptiones tam novorum, quam notabilium fungorum (in Latin). Leipzig, Germany: Gesnerus, Usterius & Wolfius. p. 42.
  5. ^ "Lactarius necator (Bull.) Pers. 1800". MycoBank. International Mycological Association. Retrieved 2010-07-13.
  6. ^ Gray SF. (1821). A Natural Arrangement of British Plants. London, UK: Baldwin, Cradock, and Joy. p. 625.
  7. ^ Kummer P. (1871). Der Führer in die Pilzkunde (in German). Zerbst, Germany: E. Luppe Staude. p. 125.
  8. ^ Kuntze O. (1898). Revisio Generum Plantarum (in Latin). Vol. 3. Leipzig, Gemany: Arthur Felix. p. 857.
  9. ^ a b Roody WC. (2003). Mushrooms of West Virginia and the Central Appalachians. Lexington, Kentucky: University Press of Kentucky. p. 107. ISBN 0-8131-9039-8.
  10. ^ Dickinson C, Lucas J. (1982). VNR Color Dictionary of Mushrooms. Van Nostrand Reinhold. p. 104. ISBN 978-0442219987.
  11. ^ a b Arora D. (1991). All that the Rain Promises and More: a Hip Pocket Guide to Western Mushrooms. Berkeley, California: Ten Speed Press. p. 19. ISBN 0-89815-388-3.
  12. ^ a b c Arora D. (1986). Mushrooms Demystified: a Comprehensive Guide to the Fleshy Fungi. Berkeley, California: Ten Speed Press. p. 73. ISBN 0-89815-169-4.
  13. ^ Hesler and Smith, 1979, p. 237.
  14. ^ Nuytinck J, Verbeken A, Rinaldi AC, Leonardi M, Pacioni G, Comandini O. (2004). "Characterization of Lactarius tesquorum ectomycorrhizae on Cistus sp. and molecular phylogeny of related European Lactarius taxa". Mycologia. 96 (2): 272–2. doi:10.2307/3762063. JSTOR 3762063. PMID 21148854.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  15. ^ a b c d Ammirati JF, Traquair JA, Horgen PA. (1985). Poisonous Mushrooms of Canada: Including other Inedible Fungi. Markham, Ontario: Fitzhenry & Whiteside in cooperation with Agriculture Canada and the Canadian Government Publishing Centre, Supply and Services Canada. pp. 273–4. ISBN 0-88902-977-6.{{cite book}}: CS1 maint: multiple names: authors list (link)
  16. ^ Smith AH. (1960). "Studies of Lactarius – II. The N.A. species of sections Scrobiculus, Crocei, Theiogali and Vellus". Brittonia. 12 (4): 306–50. doi:10.2307/2805123. JSTOR 2805123.
  17. ^ Hesler and Smith, 1979, pp. 277–78.
  18. ^ "Lactarius nordmanensis; Russulaceae (MICH5267)". Herbarium Fungus Collection Database. University of Michigan. Retrieved 2010-07-13.
  19. ^ Redhead S, Groves JW. (1979). Edible and Poisonous Mushrooms of Canada. Ottawa, Canada: Research Branch, Agriculture Canada. ISBN 0-660-10136-X.
  20. ^ Elvin-Lewis MPF, Lewis WH. (2003). Medical Botany: Plants Affecting Human Health. Chichester, UK: John Wiley & Sons. p. 61. ISBN 0-471-62882-4.
  21. ^ Steidle H. (1930). "Contributions to the toxicology of the higher mushrooms. 1st note: Lactarius torminosus". Archiv für Experimentalle Pathologie und Pharmakologie. 151 (3/4): 232–54.
  22. ^ a b Grönwall O, Pehrson Å. (1984). "Nutrient contents in fungi as a primary food of the red squirrel Sciurus vulgaris L.". Oecologia (Berlin). 64 (2): 230–1. doi:10.1007/BF00376875. JSTOR 4217450.
  23. ^ Knudsen H, Borgen T. (1994). "The Lactarius torminosus-group in Greenland". Mycologia Helvetica. 2: 49–56.
  24. ^ Bessette et al., 2009, p. 228.
  25. ^ Evenson VS. (1997). Mushrooms of Colorado and the Southern Rocky Mountains. Westcliffe Publishers. p. 77. ISBN 978-1565791923.
  26. ^ Schalkwijk-Barendsen HME. (1991). Mushrooms of Western Canada. Edmonton, Canada: Lone Pine Publishing. p. 215. ISBN 0-919433-47-2.
  27. ^ Guzmán G. (1973). "Some distributional relationships between Mexican and United States mycofloras". Mycologia. 65 (6): 1319–30. doi:10.2307/3758146. JSTOR 3758146. PMID 4773309.
  28. ^ Rogerson CT, Samuels GJ. (1994). "Agaricolous species of Hypomyces". Mycologia. 86 (6): 839–66. doi:10.2307/3760597. JSTOR 3760597.
  29. ^ Widen KG, Seppa EL. (1979). "15-Hydroxyblennin A, a new lactarane-type sesquiterpene lactone isolated from Lactarius torminosus". Phytochemistry. 18 (7): 1226–7. doi:10.1016/0031-9422(79)80144-2.
  30. ^ Cerri R, de Simone F, Senatore F. (1981). "Sterols from three Lactarius species". Biochemical Systematics and Ecology. 9 (4): 247–8. doi:10.1016/0305-1978(81)90002-8.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  31. ^ Camazine S, Lupo TL Jr. (1984). "Labile toxic compounds of the Lactarii: the role of the laticiferous hyphae as a storage depot for precursors of pungent dialdehydes". Mycologia. 76 (2): 355–8. doi:10.2307/3793113. JSTOR 3793113.

Cited text

  • Hesler LR, Smith AH. (1979). North American Species of Lactarius. Michigan: The University of Michigan Press. ISBN 0-472-08440-2.

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