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The Genus Marasmius  

[ Basidiomycetes > Agaricales > Marasmiaceae . . . ]

by Michael Kuo

Many Marasmius species are tiny, and often overlooked by collectors. However, they play an essential role in forest ecosystems, helping to break down the litter layer of the forest floor. In fact the litter layer, particularly in oak-hickory woods in eastern North America, is often teeming with Marasmius fruitbodies, even when conditions are extremely dry and hot.

Despite their tiny size, many Marasmius species are tough little mushrooms. In dry conditions they simply shrivel up and wait for the next rain. You can find them in this state if you drop to the ground and sift through the leaves or needles carefully, searching for hair-thin stems with tiny, dried-out mushroom caps attached. If you then take the mushrooms home and drop them in water, they will often assume their normal proportions. (This, by the way, is entertaining about one time only.)

Aside from their "marcescence" (the mycological term for their reviving ablility), species of Marasmius are recognized by the white spore print; the tiny to small, flat-to-convex (not conical) caps; the often wiry stems; the habitat on needle duff, leaf litter, or woody debris; and microscopic features. Even so, confusion with Gymnopus, Mycena, and several other genera is pretty much a given when it comes to Marasmius identification.

Identifying individual species of Marasmius sometimes hinges on microscopic examination, though some species have distinctive colors, textures, odors, and tastes to help narrow down the possibilities. Whatever you do, don't pick one tiny Marasmius and expect to identify it. You'll need several--many, even--in order to assess various features. And be sure to take note of your mushrooms' ecology; many Marasmius species are limited to certain substrates and ecosystems.

Most of the mushrooms in Marasmius are too small to be considered for the table, but the "Fairy Ring Mushroom," Marasmius oreades, is a popular edible (once the tough stems have been removed). However, edibility is not known for most of the species, and Marasmius identification is difficult; I don't recommend experimenting.

 		 

Marasmius rotula

Marasmius sp.

Marasmius sullivantii


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Key to 60+ Species of Marasmius in North America


1.Decomposing debris of plants (grasses, sedges, rushes, ferns, flowers, vines, etc.).
2

1.Decomposing tree litter.
10


2.Growing from the ground in troops or fairy rings in grassy areas; cap buff to tan, 1-5 cm across and usually broadly bell-shaped; gills well spaced.

2.Not growing from the ground; cap much smaller (rarely over 15 mm across).
3


3.On litter of salal and Oregon grape; odor of garlic; Pacific Northwest.
Marasmius salalis

3.Substrate different; odor not distinctive; variously distributed.
4


4.On litter of mountain avens or on living avens; arctic and alpine ecosystems.
Marasmius epidryas
at CMM (photo only)

4.Substrate different; variously distributed.
5


5.Fresh cap white, buff, or pale (perhaps with a slightly darker center); western species.
6

5.Fresh cap more highly colored; eastern and western species.
8


6.Mature cap to only 2 mm across, buff to pale fawn with a cinnamon center; spores 8-12 x 4-6 µ.
Marasmius limosus
at BioImages

6.Not as above.
7


7.Cap pure white; spores 13-16 x 5-6.5 µ.
Marasmius caricis

7.Cap whitish with pinkish to cinnamon tinges over the center; spores 8-9 x 4 µ.
Marasmiellus vaillantii
at Roger's Mushrooms


8.Base of stem without prominent basal mycelium or fuzz; spores 7-11 x 3-5 µ.
Marasmius graminum
at Fungi of Poland

8.Base of stem with mycelium or fuzz; spores variously sized.
9


9.Pennsylvania to Louisiana and Illinois; spores 13-19 x 3.5-5 µ.
Marasmius pseudobambusinus

9.Widely distributed; spores 8.5-10.5 x 3.5-4 µ.


10.On debris of conifers.
11

10.On debris of hardwoods.
27


11.Odor of garlic or onions, or strong and foul (crush a cap between your thumb and finger).
12

11.Odor not distinctive.
16


12.Odor strong and foul, but not of garlic or onions; on spruce and fir needles (one or two mushrooms per needle); stem base without mycelium; cap dull brown, beige, or nearly white.
Micromphale perforans
at Fungi of Poland

12.Odor distinctly of garlic or onions.
13


13.Mature cap extremely tiny (under 3 mm across); whitish, dull pinkish, or brownish gray. I see no convincing way to separate these two species, with or without a microscope.
Marasmiellus filopes
Marasmius thujinus

13.Mature cap larger than above (4 to 20 mm across); more highly colored.
14


14.Stem surface smooth.
Marasmius scorodonius
at Roger's Mushrooms

14.Stem surface more or less velvety.
15


15.Scattered or in loose troops on litter of pines (Pinus species); maximum cap size about 10 mm; stem base inserted directly into needles; spores 7.5-9 x 3-4 µ.
Marasmius thiersii

15.In dense troops on litter of Douglas-fir, true firs (Abies species) or pines (Pinus species); maximum cap size about 20 mm; stem base not inserted directly; spores 9-10 x 5-6 µ.
Marasmius applanatipes


16.Fresh cap whitish to very pale grayish or faintly pinkish.
17

16.Fresh cap more highly colored.
18


17.Growing from needles; stem remaining fairly pale; spores 9-10 x 3.5-4.5 µ.

17.Growing from twigs; stem darkening from the base up with age; spores 11-15 x 3.5-5.5 µ.
Marasmiellus candidus
at Roger's Mushrooms


18.Fresh cap rose, pink, red, wine colored, purple-red, etc.
19

18.Fresh cap otherwise colored (orange, brown, orangish brown, cinnamon, rust, olive brown, yellow brown . . . ).
21


19.Cap conspicuously pleated; rose pink, fading to pinkish with a darker center; growing on needles east of the Rocky Mountains.

19.Cap not conspicuously pleated; more highly colored when fresh; growing on various substrates; western.
20


20.Growing on well decayed wood; cap 5-20 mm across; gills often with a tiny tooth running down the stem; spores 8-13 x 3-4 µ.
Marasmiellus papillatus

20.Growing on humus; cap 10-40 mm across; gills often nearly free; spores 11-15 x 5-6.5 µ.


21.Cap conspicuously pleated; eastern species.
22

21.Cap somewhat lined or not, but not conspicuously pleated; eastern and western species.
23


22.Fresh cap orange to brownish orange; common from about Tennessee northward; spores 16-23 x 3-4 µ; odor not distinctive; taste mild to slightly bitter; large cystidia with refractive contents present.

22.Fresh cap cinnamon or rusty brown; common from about Tennessee southward; spores 15-18 x 3-4.5 µ; odor and taste often mealy; cystidia absent or rare (if present, without refractive contents).
Marasmius fulvoferrugineus


23.Cap olive brown, fading to light yellowish brown, pale olive brown, or grayish brown (the center often darker than the margin); often growing with ferns nearby; stem with a long root that extends into the substrate; spores shaped like lemons.
Rhizomarasmius undatus
at Roger's Mushrooms
= Marasmius undatus

23.Cap without olive tones; root lacking; spores otherwise shaped.
24


24.Growing on debris of Redwoods on the West Coast; cap brown to brownish orange or orangish, 6-12 mm wide; taste (not odor) strongly garlic-like after 1-2 minutes.
Micromphale sequoiae

24.Not completely as above.
25


25.Cap more or less "brown," without orange shades.
26

25.Cap with orange to orange-brown shades, fading to dull apricot.


26.Cap pale brownish or yellowish brown, with a darker brown center; gills without cystidia.
Marasmius pallidocephalus

26.Cap medium brown to dark brown; gill edges with upside-down mutant cow udders in miniature ("diverticulate" or "broom" cells) as cystidia.
Marasmius androsaceus
at Roger's Mushrooms


27.Growing on debris of Madrone, Tanoak, Sycamore, black locust, birch, Quaking Aspen, black cottonwood, or American holly. Several of the subsequent species are not repeated later in the key.
28

27.Growing on debris of other hardwoods.
38


28.Growing on petioles of sycamore leaves; cap minute, pale becoming pinkish brown.

28.Not as above.
29


29.Growing on bark litter of madrone; cap to 1 cm across, brown; odor and taste of garlic or onions.
Micromphale arbuticola

29.Not as above.
30


30.Growing on litter of black locust; cap 4-13 mm across, pale orange (usually darker over the center and paler marginally), strongly or faintly pleated; recorded from Michigan but probably to be expected throughout the range of the tree.
Marasmius robinianus

30.Not as above.
31


31.Growing on leaf litter of American holly; cap minute, pale with a darker brownish center.
32

31.Not as above.
33


32.Gills attached by means of a collar that encircles the stem.
Marasmius ilicola

32.Gills attached directly to the stem.
Marasmius ilicis


33.Growing on debris of tanoak.
34

33.Growing on debris of birch, quaking aspen, or black cottonwood.
36


34.Odor of garlic or onions; cap 5-10 mm across, dark reddish brown.
Marasmius thiersii

34.Odor not distinctive; other features variable.
35


35.Cap to 6 mm across, dark brown fading to light brown.

35.Not as above.
38


36.Cap tiny (5 mm across maximum) and whitish.
37

36.Not as above.
38


37.Growing on leaves of birch or quaking aspen; spores 8-11 µ long; basidia 4-spored.
Marasmius epiphyllus
at Roger's Mushrooms

37.Growing on leaves of black cottonwood (Populus trichocarpa); spores 11-14 µ long; basidia 2-spored.
Marasmius tremulae


38.Odor of garlic or onions (crush a cap between your thumb and finger).
39

38.Odor not distinctive, somewhat foul, spermatic, bleachlike, mealy, or radishlike--but not of garlic.
40


39.Found in western North America.

39.Found east of the Rocky Mountains.
Marasmius copelandii var. olidus
at Roger's Mushrooms
= Marasmius olidus


40.Fresh cap rose pink, red, purplish red, or wine colored.
41

40.Fresh cap otherwise colored.
45


41.Found in western North America.
42

41.Found east of the Rocky Mountains.
43


42.Growing on well decayed wood; cap .5-2 cm across; gills often with a tiny tooth running down the stem; spores 8-13 x 3-4 µ.
Marasmiellus papillatus

42.Growing on humus; cap 1-4 cm across; gills often nearly free; spores 11-15 x 5-6.5 µ.


43.Cap rose pink, fading to pinkish with a darker center.

43.Cap purple red to red, perhaps fading to reddish brown.
44


44.Gills pinkish, often with red edges; spores 16-22 x 4-5.5 µ.
Marasmius haematocephalus
at Badidiomycetes of Greater Antilles

44.Gills whitish to yellowish, the edges colored like the faces; spores 8.5-12 x 3-4 µ.
Marasmius bellipes


45.Mature cap regularly at least 2-3 cm across (often even larger); stem not wiry. (If cap is 2-3 cm across and the stem is not wiry, try this choice first.)
46

45.Mature cap rarely as wide as 2-3 cm; stem wiry or not.
52


46.Cap whitish with a dark brown or reddish brown center; found in eastern North America.

46.Not as above.
47


47.Entire stem remaining pale (whitish to yellow or very pale brownish) throughout development.
48

47.At least the lower portion of stem dark (brown, reddish brown, orange-brown, etc.) by maturity.
49


48.Growing from leaf litter; cystidia present only on gill edges.

48.Growing from leaf litter, twigs, or logs; cystidia present on gill faces and edges.
Marasmius cystidiosus
at Roger's Mushrooms


49.Fresh cap pale (whitish, yellowish, pinkish cinnamon).
50

49.Fresh cap some shade of brown.
51


50.Mature cap whitish with a very slightly darker center, becoming somewhat wrinkled; gills with dextrinoid cystidia (setae).

50.Mature cap pinkish cinnamon with a paler margin, not usually wrinkled; gills with colorless cystidia and broom cells.
Marasmius spissus


51.Often growing in clusters of 2-3 mushrooms; gills with dextrinoid cystidia (setae).

51.Usually growing scattered to gregariously; gills with colorless to yellowish cystidia and broom cells.
Marasmius floridanus
= Marasmius spadiceus


52.Fresh cap white or nearly so (pale yellowish, buff, cream).
53

52.Fresh cap more highly colored.
60


53.Cap conspicuously pleated.
54

53.Cap smooth to wrinkled or faintly lined, but not conspicuously pleated.
55


54.Usually growing on sticks, woody debris, and logs; cap at maturity with a flat top in side view.

54.Usually growing on leaves; cap at maturity evenly rounded-convex in side view.


55.Cap minute (2 mm maximum width); growing on leaves of American Beech.
Marasmius epifagus

55.Not as above.
56


56.Stem surface smooth or minutely pubescent.
57

56.Stem surface finely to prominently hairy (use a hand lens on fresh specimens).
58


57.Cap 2-13 mm across; usually growing on sedges, rushes, ferns (etc.) but also recorded on twigs of alder, willow, beech, tulip poplar, sycamore, pine, and hemlock; cystidia not dextrinoid.
Marasmiellus vaillantii
at Roger's Mushrooms

57.Cap 7-40 mm across; usually growing on twigs or leaves of oaks, but recorded on debris of other hardwoods; cystidia dextrinoid.


58.Entire stem remaining pale over the course of development.
Marasmius falcatipes

58.At least the bottom portion of the stem darkening to pale brown, brown, or black with maturity.
59


59.Stem soon black except at the apex; spores triangular to jack-shaped.

59.Stem becoming yellow-brown to brown except at the apex; spores pip-shaped (elliptical with a pinched end).
Marasmius epiphyllus
at Roger's Mushrooms


60.Color of fresh cap ranging from orange to orange-brown to rusty or reddish brown.
61

60.Color of fresh cap ranging from brown to light brown to yellow-brown to tan or olive brown.
69


61.Mature cap conspicuously pleated or prominently lined.
62

61.Mature cap smooth or faintly lined, but not conspicuously lined or pleated.
66


62.Spores under 12 µ in length; cap initially brown to yellow-brown but sometimes fading to orangish brown; growing on leaves.
Marasmius glabellus

62.Spores longer than 12 µ; cap with orange or rusty shades from the beginning; growing on leaves or woody debris.
63


63.Cap 3-8 mm across; rare; documented from Tennessee.
Marasmius haematocephalus var. anomaloides

63.Cap larger than above; common throughout eastern North America.
64


64.Found in northeastern North America from roughly the 43rd parallel northwards; many spores under 15 µ in length; odor reminiscent of Pleurotus ostreatus.
Marasmius borealis

64.Found south of the 43rd parallel or perhaps above it; nearly all spores longer than 15 µ; odor not distinctive or mealy.
65


65.Fresh cap orange to brownish orange; common from about Tennessee northward; spores 16-23 x 3-4 µ; odor not distinctive; taste mild to slightly bitter; large cystidia with refractive contents present.

65.Fresh cap cinnamon or rusty brown; common from about Tennessee southward; spores 15-18 x 3-4.5 µ; odor and taste often mealy; cystidia absent or rare (if present, without refractive contents).
Marasmius fulvoferrugineus


66.Stem densely hairy, long and usually rooting somewhat; cap cuticle without broom cells.

66.Stem smooth or very finely hairy, usually not rooting; cap cuticle with broom cells.
67


67.Found in northeastern North America from roughly the 43rd parallel northwards; spores over 12 µ in length; odor reminiscent of Pleurotus ostreatus.
Marasmius borealis

67.Widely distributed; spores shorter than 12 µ; odor not distinctive.
68


68.Apparently limited to eastern North America; cap 6-25 mm across, bright orange or dark orange-brown when fresh; broom cells and cystidia present on gills.

68.Apparently widely distributed in North America; cap 4-12 mm across, orange to orangish but rarely bright orange; broom cells present on gills but not cystidia.


69.Basal half of stem remaining fairly pale through maturity.
70

69.At least the basal half of the stem dark brown to black by maturity.
71


70.Stem usually eccentric (sometimes central); stature minute (cap 1-7 mm across, stem under 3 mm long).
Marasmius falcatipes

70.Stem usually central (sometimes slightly erratic); small but not minute (cap 3-24 mm across, stem 26-40 mm long).
Marasmius insipidus


71.Usually growing on curled, blackened ash leaves (but recorded on elm, poplar, and other hardwood leaves); cap minute (under 4 mm across), grayish brown to light brown.
Marasmius minutus

71.Not completely as above.
72


72.Growing on leaves of oaks or tanoak in western North America; cap minute (2-5 mm across), light brown over the center and paler marginally.

72.Not completely as above.
73


73.Stem quite long (60-100 mm long), with a scurfy surface.
Marasmius chordalis

73.Stem shorter than above (between 5 and 65 mm long), with a smooth to faintly hairy or pubescent surface.
74


74.Spores under 12 µ long.
Marasmius glabellus

74.Spores over 13 µ long.
75


75.Cap conspicuously pleated at maturity; stem smooth; odor spermatic; spores 16-24 µ long.
Marasmius paludigenus

75.Cap wrinkled or somewhat lined along the margin at maturity, but not conspicuously pleated; stem faintly hairy or pubescent; odor not distinctive; spores 13.5-18 µ long.
Marasmius ciliatomarginatus




References

Abesha, E. et al. (2003). Population genetics and spatial structure of the fairy ring fungus Marasmius oreades in a Norwegian sand dune ecosystem. Mycologia 95: 1021-1031.

Antonin, V. et al. (1997). Generic concepts within the groups of Marasmius and Collybia sensu lato. Mycotaxon 63: 359-368.

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

Blenis, P. V. et al. (1997). Evaluation of fungicides and surfactants for control of fairy rings caused by Marasmius oreades (Bolt ex. Fr.) Fr. HortScience 32: 1077-1084.

Desjardin, D. E. (1985). New marasmioid fungi from California. Mycologia 77: 894-902.

Desjardin, D. E. (1987). The Agaricales (Gilled Fungi) of California. 7. Tricholomataceae I. Marasmioid Fungi: the Genera Baeospora, Crinipellis, Marasmiellus, Marasmius, Micromphale, and Strobilurus. Eureka, CA: Mad River Press. 99 pp.

Desjardin, D. E. & Petersen, R. H. (1989). Studies on Marasmius from eastern North America. II. New species. Mycotaxon 34: 71-92.

Desjardin, D. E. (1991). Studies on Marasmius from eastern North America. IV. Additions to Sect. Sicci. Mycologia 83: 30-39.

Doyle, M. F. & Sundberg, W. J. (1989). The taxonomy, ecology, and distribution of Marasmius (Agaricales, Tricholomataceae) in Illinois. Transactions of the Illinois Academy of Science 82: 109-120.

Farnet, A. M. et al. (1999). Genotypic variations among isolates of Marasmius quercophilus, a white-rot fungus isolated from evergreen oak litter. Canadian Journal of Botany 77: 884-890.

Gilliam, M. S. (1975). New North American species of Marasmius. Mycologia 67: 817-844.

Gilliam, M. S. (1975). Marasmius section Chordales in the Northeastern United States and Canada. Contributions from the University of Michigan Herbarium 11: 25-40.

Gilliam, M. S. (1976). The genus Marasmius in the northeastern United States and adjacent Canada. Mycotaxon 4: 1-144.

Gordon, S. A. & Petersen, R. H. (1997). Infraspecific variation among geographically separated collections of Marasmius androsaceus. Mycological Research 101: 365-371.

Gordon, S. A. & Petersen, R. H. (1998). Infraspecific variation among geographically separated collections of Marasmius scorodonius. Mycotaxon 69: 453-466.

Gordon, S. A. et al. (1994). Mating systems in Marasmius: Additional evidence to support sectional consistency. Mycological Research 98: 200-204.

Halling, R. E. (1983). A synopsis of Marasmius section Globulares (Tricholomataceae) in the United States. Brittonia 35: 317-326.

McFarland, K. P. & Rimmer, C. C. (1996). Horsehair fungus, Marasmius androsaceus, used as nest lining by birds of the subalpine spruce-fir community in the northeastern United States. The Canadian Field-Naturalist 110: 541-543.

Moser, M. (1983). Keys to Agarics and Boleti (Polyporales, Boletales, Agaricales, Russulales). Ed. Kibby, G. Transl. Plant, S. London: Roger Phillips. 535 pp.

Murphy, J. (2005). Trial key to species of marasmioid fungi in the Pacific Northwest. Retrieved October, 2006 from the Pacific Northwest Key Council Web site: http://www.svims.ca/council/Marasm.doc

Petersen, R. H. (2000). Rhizomarasmius, gen. nov (Xerulaceae, Agaricales). Mycotaxon 75: 333-342.

Phillips, R. (1991). Mushrooms of North America. Boston: Little, Brown and Company. 319 pp.

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

Wilson, A. W. & D. E. Desjardin (2005). Phylogenetic relationships in the gymnopoid and marasmioid fungi (Basidiomycetes, euagarics clade). Mycologia 97: 667-679.



Cite this page as:

Kuo, M. (2006, October). The genus Marasmius. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/marasmius.html