Lactarius pubescens

Lactarius pubescens, commonly known as the downy milk cap, is a species of fungus in the family Russulaceae. It is a medium to large agaric with a creamy-buff, hairy cap, whitish gills and short stout stem. The fungus has a cosmopolitan distribution, and grows solitarily or in scattered groups on sandy soil under or near birch.

Lactarius pubescens
Scientific classification
Kingdom:
Fungi
Division:
Basidiomycota
Class:
Agaricomycetes
Order:
Russulales
Family:
Russulaceae
Genus:
Lactarius
Species:
L. pubescens
Binomial name
Lactarius pubescens
(Fr.) Fr. (1838)
Synonyms[1]

Agaricus pubescens Fr. (1794)
Lactarius controversus var. pubescens (Fr.) Gillet (1876)
Lactifluus pubescens (Fr.) Kuntze (1891)
L. torminosus subsp. pubescens (Fr.) Konrad & Maubl. (1935)
L. torminosus var. pubescens (Fr.) S.Lundell (1956)

Lactarius pubescens
float
Mycological characteristics
gills on hymenium
cap is depressed
hymenium is decurrent
stipe is bare
spore print is cream
ecology is mycorrhizal
edibility: unknown

Edibility: Ambiguous and controversial. In Russia is consumed after prolonged boiling followed by a marinating process. However it is reported to have caused gastro-intestinal upsets. Therefore, its consumption should not be recommended and this species considered toxic.

Taxonomy and phylogeny
 
 
 

L. quietus

 
 
 
 
 

L. intermedius

 
 

L. scrobiculatus

 
 
 
 

L. spinulosus

 
 
 
 

L. mairei var. ilicis

 
 

L. mairei

 
 
 
 
 

L. torminosus

 
 

L. torminosulus

 
 
 
 

L. pubescens

 
 

L. scoticus

 
 

L. tesquorum

 
 
 
 
 
 
 
 
 
Phylogeny and relationships of L. pubescens and related species based on ITS sequences.[2]

The species was first named by German botanist Heinrich Schrader as Agaricus pubescens in 1794.[3] Elias Magnus Fries gave it its current name in 1838.[4] The species has also been treated as a variety of Lactarius controversus (as L. controversus var. pubescens by Gillet in 1876)[5] and as both a subspecies (as Lactarius torminosus subsp. pubescens by Paul Konrad and André Maublanc in 1935)[6] and a variety (as L. torminosus var. pubescens by Lundell in 1956)[7] of Lactarius torminosus.[1]

Lactarius pubescens is classified in the section Piperites, subsection Piperites. This includes related Lactarius species characterized by having a latex that does not become yellow upon exposure to air, and which does not stain freshly cut surfaces of the fruit body yellow.[8] Based on phylogenetic analysis published in 2004, L. pubescens is most closely related to L. scoticus and L. tesquorum.[2]

The mushroom is commonly known as the "downy milkcap". The specific epithet pubescens is derived from Latin, and means "becoming downy".[9]

Description
The gills are crowded, and whitish to pale yellow in color.

The cap is 2.5–10 cm (1.0–3.9 in) wide, obtuse to convex, becoming broadly convex with a depressed center. The margin (cap edge) is rolled inward and bearded with coarse white hairs when young. The cap surface is dry and fibrillose except for the center, which is sticky and smooth when fresh, azonate, white to cream, becoming reddish-orange to vinaceous (red wine-colored) on the disc with age. The gills are attached to slightly decurrent, crowded, seldom forked, whitish to pale yellow with pinkish tinges, slowly staining brownish ochraceous when bruised. The stem is 2–6.5 cm (0.8–2.6 in) long, 6–13 mm (0.24–0.51 in) thick, nearly equal or tapered downward, silky, becoming hollow with age, whitish when young, becoming ochraceous from the base up when older, apex usually tinged pinkish, often with a white basal mycelium. The flesh is firm, white; odor faintly like geraniums or sometimes pungent, taste acrid. The latex is white upon exposure, unchanging, not staining tissues, taste acrid. The spore print is cream with a pinkish tint. The edibility of Lactarius pubescens has been described as unknown,[10] poisonous,[11] and even edible.[12]

The spores are 6–8.5 by 5–6.5 µm, elliptic, ornamented with warts and ridges that sometimes form a partial reticulum, prominences up to 1.5 µm high, hyaline (translucent), and amyloid. The cap cuticle is a layer of thin-walled hyphae.[10]

Varieties
  • Lactarius pubescens var. betulae (A.H. Sm.) Hesler & A.H. Sm. 1979
  • Lactarius pubescens var. betularum (Bon) Bon 1985
  • Lactarius pubescens var. scoticus (Berk. & Broome) Krieglst. 1991

Ectomycorrhizae

The ectomycorrhizae that L. pubescens forms in association with Betula pendula and Populus tremuloides has been grown in pure culture and described scientifically.[13][14]

Similar species

Lactarius scoticus Berk. & Broome is a small morphological mimic of L. pubescens, growing in arctic-alpine birch.[15] L. pubescens is often mistaken for L. torminosus which has larger spores (7–10 by 6–8 µm).[16]

Habitat and distribution

The fruit bodies of L. pubescens are found scattered or in groups on the ground in wet areas under birch and other hardwoods from August to October. The fungus is common all over temperate Europe and has been reported from eastern North America, the Pacific Northwest, Arizona, California, Colorado, Idaho, and western Canada; its frequency of appearance is occasional.[10] It is also found in Greenland,[17] and was reported for the first time in Rome, Italy, in 1997.[18]

Bioactive compounds

The marasmane sesquiterpenoid pubescenone and the sesquiterpene aldehyde lactaral have been isolated from the fruit bodies of L. pubescens.[19]

See also

References
  1. "Species synonymy: Lactarius pubescens (Fr.) Fr". Index Fungorum. CAB International. Retrieved 2010-07-12.
  2. 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): 272–82. doi:10.2307/3762063. JSTOR 3762063. PMID 21148854. Retrieved 2010-07-12.
  3. Schrader H. (1794). Spicilegium Florae Germanicae (in Latin). Hanover: Impensis Christiana Ritscheri. p. 122. Retrieved 2010-07-12.
  4. Fries EM (1838). Epicrisis Systematis Mycologici, seu Synopsis Hymenomycetum (in Latin). Upsaliae: Typographia Academica. p. 335. Retrieved 2010-07-12.
  5. Gillet CC. (1876). Les Hyménomycètes ou Description de tous les Champignons qui Croissent en France [Hymenomycetes or descriptions of tall the mushrooms which grow in France] (in French). p. 210.
  6. Konrad P, Maublanc A (1935). Bull. Trimestriel Soc. Mycol. France. 51: 129. Missing or empty |title= (help)
  7. Lundell S, Nannfeldt JA (1956). Fungi Exsiccati Suecici. Fasc. 47-48: 2301–2400. Missing or empty |title= (help)
  8. Hesler & Smith, 1979, p. 237.
  9. Schalkwijk-Barendsen HME. (1991). Mushrooms of Western Canada. Edmonton: Lone Pine Publishing. p. 215. ISBN 978-0-919433-47-2.
  10. Bessette AR, Bessette A, Harris DM (2009). Milk Mushrooms of North America: A Field Guide to the Genus Lactarius. Syracuse: Syracuse University Press. pp. 228–29. ISBN 978-0-8156-3229-0.
  11. Phillips, Roger (2010) [2005]. Mushrooms and Other Fungi of North America. Buffalo, NY: Firefly Books. p. 112. ISBN 978-1-55407-651-2.
  12. Boa E. (2004). Wild Edible Fungi: A Global Overview Of Their Use And Importance To People (Non-Wood Forest Products). Food & Agriculture Organization of the UN. p. 135. ISBN 978-92-5-105157-3. Retrieved 2010-07-12.
  13. Godbout C, Fortin JA (1985). "Synthesised ectomycorrhizas of aspen: fungal genus level of structural characterisation". Canadian Journal of Botany. 63 (2): 252–62. doi:10.1139/b85-029.
  14. Ingleby K, Mason PA, Last FT, Fleming LV. 1990. Identification of ectomycorrhizas. London, UK: Institute of Terrestrial Ecology Research Publication No. 5, HMSO. 112 p.
  15. Jahn H. (1982). "Über Lactarius pubescens und L. favrei sp. nov". International Journal of Mycology and Lichenology (in German). 1: 75–116.
  16. Arora D. (1986). Mushrooms Demystified: a Comprehensive Guide to the Fleshy Fungi. Berkeley, CA: Ten Speed Press. p. 73. ISBN 978-0-89815-169-5. Retrieved 2010-07-12.
  17. Knudsen H, Borgen T (1994). "The Lactarius torminosus-group in Greenland". Mycologia Helvetica. 6 (2): 49–56. ISSN 0256-310X.
  18. Perrone L. (1997). "Un alieno a Roma. Lactarius pubescens (Fr.) Fr. 1836" [A new record for Rome. Lactarius pubescens (Fr.) Fr. 1836]. Bollettino Dell'Associazione Micologica ed Ecologica Romana (in Italian). 40: 11–19.
  19. Shao HJ, Wang CJ, Dai Y, Wang F, Yang WQ, Liu JK (2007). "Pubescenone, a new marasmane sesquiterpenoid from the mushroom Lactarius pubescens". Heterocycles. 71 (5): 1135–39. doi:10.1002/chin.200741158.

Cite text
  • Hesler LR, Smith AH (1979). North American Species of Lactarius. Michigan: The University of Michigan Press. ISBN 978-0-472-08440-1.
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