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The Genus Laccaria  

[ Basidiomycetes > Agaricales > Hydnangiaceae . . . ]

by Michael Kuo

Laccaria species form a fairly easily recognized group of white-spored mushrooms. The gills are often thick and waxy, and are usually purple, pinkish, or (Caucasian) flesh-colored. The cap colors range from whitish to, more commonly, orangish brown or reddish brown--while a few species are purple. Laccarias are never slimy, which helps in separating them from the waxy caps, and their gills are attached to the stem but do not run down it, helping distinguish them from species of Clitocybe.

Laccarias are mycorrhizal, forming symbiotic partnerships with trees. There is evidence that at least some species of Laccaria may serve as pioneers in disturbed ground or de-forested areas that have recently begun the long road of ecological succession that leads, eventually, to a "mature" ecosystem. Thus, for example, several species of Laccaria are frequently found in young pine plantations.

Laccaria identification is frequently a fairly easy matter of carefully observing the mushroom's ecology and visible features--but I hasten to add that there is a catch: you must, in some cases, have fresh, young specimens available in order to judge the color (whitish or lilac) of the basal mycelium, since the purplish fuzz notoriously fades to whitish, often doing so fairly early in development. Microscopic analysis is required in order to sift through a few species clusters, and includes spore morphology and "prong counting" (determining whether basidia are two- or four-spored).

DNA evidence, so far, has upheld Laccaria as a "good" genus, though its precise position among the gilled mushrooms has not been thoroughly resolved. Mating studies have tended to support the species traditionally delimited by morphology, though they have also suggested that there may be some biological species that cannot be separated on the basis of their physical features; for example, Laccaria bicolor in North America appears to consist of at least two groups that are intersterile, and cannot "mate," though the mushrooms look the same to the naked eye and the microscope.

If you are an Internet mushroom junky, you should definitely visit Laccaria expert Greg Mueller's wonderful site, The Mushroom Genus Laccaria in North America, hosted at the Field Museum of Natural History in Chicago.

 		 

Laccaria laccata

Laccaria ochropurpurea

Laccaria ohiensis



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Key to 19 Laccaria Species in North America  


1.Growing in sand.
2

1.Growing elsewhere.
4


2.Associated with live oak (Quercus virginiana) on the Gulf Coast; spores under 10 µ long.
Laccaria vinaceobrunnea
at Mueller's Laccaria

2.Not growing with live oak on the Gulf Coast; spores much longer than 10 µ.
3


3.Known only from eastern Canada; basal mycelium whitish; spores with clearly defined spines.
Laccaria maritima
at Mueller's Laccaria

3.Known from eastern North America and the Great Lakes region; basal mycelium purplish; spores roughened but without clearly defined spines.


4.Gills clearly purple (like, purple purple) when fresh, and usually remaining so as the mushroom matures.
5

4.Gills variously colored (vinaceous, flesh-colored, lilac, pinkish, etc.) but not clearly purple--or if pale purplish when young, soon fading to pinkish, flesh color, etc.
8


5.Growing in western North America under conifers.

5.Growing east of the Rocky Mountains, under hardwoods or conifers.
6


6.Mature cap over 4 cm across, purplish when young but soon buff, whitish, or pale brownish; stem as wide as 2-3 cm when mature.

6.Mature cap smaller than 4 cm across, variously colored; stem 1 cm wide or less when mature.
7


7.Associated with live oak (Quercus virginiana) on the Gulf Coast; cap purplish becoming brownish.
Laccaria vinaceobrunnea
at Mueller's Laccaria

7.Associated with oaks or beech in eastern North America; cap purple, fading to lilac or buff.


8.Associated with Eucalyptus; cap 1-3.5 cm across, rusty reddish brown, fading to buff, not lined or merely faintly lined; stem 2-6 cm long.

8.Not completely as above.
9


9.Mature cap under 3 cm across, strongly lined; stem less than 4 mm thick.
10

9.Mature cap usually larger than above, lined or not; stem usually thicker than above.
12


10.Stem 2-7 cm long, reddish brown, contrasting with paler overall color of mature cap.
Laccaria striatula
at Mueller's Laccaria

10.Stem shorter than above, colored like the cap.
11


11.Young cap with a wine-colored tinge that soon fades to reddish brown or orangish brown; basidia 2-spored.
Laccaria tortilis
at Mueller's Laccaria

11.Young cap without a wine-colored tinge, reddish brown or orangish brown; basidia 4-spored.


12.Growing under hardwoods with no conifers nearby; not growing in sphagnum; not found in arctic, boreal, or montane areas.

12.Growing under conifers--or if growing under hardwoods, then under birches or willows in arctic, boreal or montane areas, or in sphagnum under alders.
13


13.Basal mycelium of fresh, young specimens lilac to purplish--though possibly soon fading to whitish.
14

13.Basal mycelium whitish in all stages of development.
17


14.Found under long-leaf pine (Pinus palustris) along the Gulf Coast; cap sometimes with purplish tones; spores elliptical, with spines under 1 µ long.
Laccaria oblongospora
at Mueller's Laccaria

14.Not completely as above.
15


15.Cap and stem conspicuously scaly; cheilocystidia always absent.
Laccaria nobilis
at Mueller's Laccaria

15.Cap and stem usually smooth, hairy, or finely scaly--but not conspicuously scaly on a regular basis; cheilocystidia usually present.
16


16.Cap pinkish to flesh-colored; cap surface with numerous but scattered perpendicular fascicles of interwoven hyphae.
Laccaria bicolor
at Mueller's Laccaria

16.Cap brownish orange to reddish brown, fading to buff; cap surface, at least over the disc, densely packed with perpendicular fascicles of interwoven hyphae, appearing nearly as a trichoderm.


17.Growing under conifers, birches, or willows in arctic, boreal, or montane (near the tree line) areas; cap usually strongly lined.
18

17.Growing elsewhere; cap lined or not.
19


18.Basidia 4-spored.
Laccaria montana
at Mueller's Laccaria

18.Basidia 2-spored.
Laccaria pumila
at Mueller's Laccaria


19.Stem 7-14 cm long; growing in moss or sphagnum, usually with spruce, tamarack, or alder nearby.

19.Stem shorter than above; usually not growing in moss or sphagnum but, if so, with pines nearby.
20


20.Spores round or nearly so, with spines 1-2 µ long; cap usually orangish brown, usually smooth or very finely hairy, usually under 5 cm across.

20.Spores broadly elliptical, with spines .5-1 µ long; cap reddish brown to orangish brown, finely hairy becoming finely scaly with maturity, 2-7 cm across.



References

Arora, D. (1986). Mushrooms demystified: A comprehensive guide to the fleshy fungi. Berkeley: Ten Speed Press. 959 pp.

Mueller, G. M. (1997). The mushroom genus Laccaria in North America. Retrieved from the Field Museum of Natural History Web site: http://www.fmnh.org/research_collections/botany/botany_sites/fungi/index.html

Smith, A. H., Smith, H. V. & Weber, N. S. (1979). How to know the gilled mushrooms. Dubuque, Iowa: Wm. C. Brown. 334 pp.




Cite this page as:

Kuo, M. (2005, February). The genus Laccaria. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/laccaria.html