Trial field key to the species of CYSTODERMA in the Pacific Northwest

Prepared for the Pacific Northwest Key Council
By Nettie Laycock and Reynaldine Sandahl, Aug. 1977

Reformatted with minor revisions by Ian Gibson 2003, 2011

Copyright © 1977, 2003 Pacific Northwest Key Council

 

 

The genus Cystoderma was established by Fayod (1889) to include certain agarics placed in the tribe Lepiota of Agaricus by Fries (1821). Smith and Singer (1945) monographed the genus and recognized fourteen species, eleven of which are known from North America. Only the species and varieties known to occur in the Pacific Northwest are included in this key. As new species are described and published the key will be revised to include them.

Material for the key has been adapted from A Monograph on the genus Cystoderma by Alexander H. Smith and Rolf Singer, and Mushrooms in their Natural Habitats by Alexander Smith.

Cystoderma is made up of a group of relatively small species (1.5 - 8 cm broad) which are characterized by their white spore deposit, attached gills, centrally attached stem which is confluent with the cap, and by the granulose covering of the cap and lower portion of the stem. A partial veil is present in all species. The colors of the fresh fruiting bodies are red, reddish brown, vinaceous (purple) brown, orange-brown, yellow, or creamy to nearly white. The colors vary in several species but are fairly constant in others. Although most Cystodermas seen will be Cystoderma amianthinum, Cystoderma fallax, or Cystodermella granulosa, a number of other species have been found in the Pacific Northwest. Albino forms of several species are known. Cystodermas may grow solitary, scattered to gregarious, or sometimes subcespitose, in both hardwood and conifer forests, on soil or on well-decayed wood but most frequently on beds of conifer needles and moss. The season is late summer through fall. We have no knowledge of any toxic species in this group; however, there is little reliable information as to their edibility. Most are too small or too rare to be of much interest or importance from the standpoint of edibility.

The key is based mostly on field characteristics and designed mainly for use by those without a microscope. However, in the modern classification, the main distinctions in Cystoderma are primarily based on microscopic features (they are often look-alikes on field characters) with the result that a positive identification may not be possible without resorting to either chemical tests or to the microscope. (Spores are typically small, entire, smooth, more or less ellipsoid, either amyloid or nonamyloid; pleurocystidia and cheilocystidia sometimes present; gill trama parallel to subparallel; pileus cuticle formed by chains of inflated cells [sphaerocysts] or the cells ellipsoid to cylindric or quite irregular in some; clamp connections regularly present.)

The minor revision of 2003 added Cystoderma carcharias and Cystoderma subpurpureum from a later paper by A.H Smith and Rolf Singer, , filled in missing details in some of the descriptions, and added a list of references. In 2011, the genus Cystodermella was accepted as outlined by Harmaja in 2002 for a group of Cystoderma species with inamyloid spores.

 

 

ACKNOWLEDGEMENTS

Sincere appreciation is expressed for personal advice and assistance from Dr. D. E. Stuntz, University of Washington, Dr. A. H. Smith, University of Michigan, Dr. E. E. Tylutki, University of Idaho, and Fr. Christopher Abair, Saint Martin's College, Olympia.

 

 

KEY TO SPECIES

1a Cap white or nearly so

1b Cap red, reddish-brown, vinaceous (purple) brown, grayish with a purple cast, orange-brown, yellow-brown, or yellow

2a Odor strong (unpleasantly moldy to gaslike), persistent ring, cap pure white (forma album) to dingy white +/- pink tint, rare

................................................................................Cystoderma carcharias

CAP 2.0-5.0 (6.0) cm, conic when young, later conic-bellshaped to flat, with sharply bent margin and obtuse umbo; dingy white to pale gray, usually with a pink tint, or if snow-white - f. album, umbo sometimes darker; finely granulose-mealy, margin usually whitish-fringed from veil remnants; flesh thick, whitish. ODOR unpleasantly moldy to gas-like. TASTE mild, unpleasant.GILLS broadly adnate and with a decurrent tooth, narrow; whitish to cream; edges smooth.STEM 2.5-5.0 (7.0) cm x 0.3-0.5 (0.7) cm, cylindric, base sometimes enlarged, solid becoming hollow; white above the ring, below the ring whitish to cream-colored, sometimes with a pink tint; above the ring smooth, below the ring granulose-floccose-banded (floccose = with easily removed cottony tufts); ring membranous, ascending, flaring to funnel-shaped, upper surface smooth, white, lower surface granulose floccose. HABIT and HABITAT solitary to gregarious, primarily in conifer forests, on needle litter, (Breitenbach for Europe), one Oregon collection of forma album from a moss carpet under second growth Douglas-fir, another of forma album from Oregon from a very dense growth of Rubus, alder, and maple, (Smith). MICROSTRUCTURES spores 3.9-5.7 x 2.9-3.8 microns, broadly elliptic, pip-shaped, smooth. REMARKS Whether the odor is distinct from that of Cystoderma amianthinum is open to question. Geosmin is a compound found in both and responsible for a "musty-earthy odor". Cystoderma amianthinum does not have a persistent ring however.

2b Odor not strongly and unpleasantly moldy to gaslike, or if odor disagreeable ring not persistent or odor is of green corn

3a Cap large, 4-5.5 cm broad, pure white when young, becoming cinnamon-buff in age, small conic scales, rare

................................................................................Cystodermella ambrosii

CAP 4-5.5 cm broad, broadly convex to nearly flat, at first covered with small white conic scales, in age becoming more or less smooth or appearing cottony fibrillose. ODOR somewhat spicy, fungoid, (Breitenbach for Europe). TASTE mild to somewhat astringent, fungoid, (Breitenbach for Europe). GILLS adnate becoming adnexed, whitish. STEM 5-9 cm x 0.8-1.2 cm, (shorter in some descriptions), white and more or less fibrillose to lacerate (torn) scaly up to the apical zone left by the thin fibrillose veil, in age becoming somewhat smooth. HABITAT solitary to gregarious inside and outside forests, primarily montane to subalpine, in pastures, on mossy gravel banks, or also on needle litter, near Spruce, Larch, or Alder, (Breitenbach for Europe). MICROSTRUCTURES spores 4-5 x 2.5-3 cm, inamyloid.

3b Cap small, rarely reaching 5 cm broad, pure white, minutely granulose-scaly

................................................................................white forms of colored species

White forms of the colored species include at least forms of Cystodermella granulosa and Cystoderma amianthinum, much less common than the colored forms. These two can be told apart by amyloid spore reaction in the latter.

 

4a (1b) Growing on well-decayed wood

4b Growing on soil, moss, humus, etc.

5a Ring prominent, membranous, persistent

................................................................................Cystoderma fallax

CAP 2-5cm broad, convex becoming expanded-umbonate at first covered with erect granulose scales which may persist in the center but finally become more or less evenly granulose or powdery, evenly amber to tawny brown. ODOR mild or at times disagreeable. (A variant of this species has a green corn odor.) TASTE not distinctive or at times somewhat nauseating. GILLS adnexed, whitish or tinged buff. STEM 3-6 cm x 0.3-0.7 cm, sheathed up to the flaring membranous ring with a granulose covering similar in color and texture to the granules on the cap, the sheath composed of an inner membranous layer on which are the closely arranged granulose scales of the outer layer, scales smaller and more poorly formed downward. MICROSTRUCTURES spores 3.5-5 x 2.8-4 microns, amyloid. REMARKS common.Cystoderma fallax
Cystoderma fallax
Steve Trudell

5b Ring inconspicuous, as zones and patches, these soon disappearing

6a Cap vermilion or bright orange-brown, usually larger than 3 cm broad

................................................................................Cystodermella cinnabarina

(also known as Cystoderma cinnabarinum and Cystoderma terrei

CAP 2-6 cm broad, convex becoming broadly convex, sometimes flat, surface covered with short, conic, fairly persistent scales, margin appendiculate at first with hanging fragments of the broken veil. GILLS bluntly adnate but often seceding and pulling away from the stem in age, white, edges minutely fimbriate (fringed) under the magnification of a hand lens. STEM 3-6 cm x 0.8-1.5 cm, sheathed up to the evanescent ring with a branny or scurfy sheath similar in color and texture to the scales on the cap. MICROSTRUCTURES spores 4-5 x 2.5-3 microns, inamyloid; cheilocystidia present. REMARKS The cap color varies considerably and this species may be confused with Cystodermella granulosa variants if one does not check for the presence of cheilocystidia. It is not clear how common this taxon is in the Pacific Northwest.Cystodermella cinnabarina
Cystodermella cinnabarina
Michael Beug

6b Cap dark cinnamon or clay color, usually smaller than 3 cm broad, rare

................................................................................Cystoderma gruberianum

CAP 1-3 cm broad, conic becoming bell-shaped to expanded-umbonate, coarsely granular texture, soon becoming powdery. ODOR and TASTE none. GILLS adnate becoming subdecurrent in age, veined in the interspaces, yellowish-buff, edges even to eroded. STEM 3-4.5 cm x 0.3-0.5 cm, with a granulose-fibrillose sheath which is concolorous with the cap, breaking into numerous scaly to hairy patches, finally becoming smooth. MICROSTRUCTURES spores 9-11.5 x 5-6 microns, strongly amyloid.

7a (4b) Ring prominent, membranous, often flaring out or upward

7b Ring inconspicuous, poorly formed and soon disappearing

8a Odor of green corn, pungent, or disagreeable

8b Odor mild or none

9a Cap yellow-brown, surface even or only slightly radially wrinkled

................................................................................Cystoderma amianthinum

CAP 1.5-3.5 (4.5) cm broad, convex expanding to broadly convex, often peaked or with obtuse umbo, yellow-brown, paler toward the margin, margin denticulate (toothed) with broken veil tissue, surface covered completely in fine powdery granules when fresh but these gradually disappear with age or on excessive handling. GILLS adnate at first, often becoming adnexed, white to buff. ODOR mild, musty-earthy, pungent, or green corn. STEM 3-6 cm x 0.3-0.5 cm, more or less the color and texture of the cap below the ragged poorly formed ring. MICROSTRUCTURES spores 4.5-6.5 x 2.8-3.5 microns, amyloid. REMARKS common. Geosmin is the compound apparently responsible for the "musty-earthy odor"Cystoderma amianthinum
Cystoderma amianthinum
Sharon Godkin

9b Cap yellow-brown, surface conspicuously radially wrinkled

................................................................................Cystoderma amianthinum f. rugosoreticulatum

This form has essentially the same appearance as Cystoderma amianthinum f. typicum except for the wrinkled cap surface and often more robust size. It is a conspicuous form when the wrinkles of the cap are well-developed but all degrees of variation are common. Frequent.

 

10a (8b) Cap vermilion or bright orange brown, usually more than 3 cm

10b Cap yellow-brown, reddish cinnamon or vinaceous (purple) brown, or grayish with a purplish cast, usually less than 4 cm broad

11a Cap grayish with a purplish cast, less than 1 cm broad, rare

................................................................................Cystodermella subpurpureum

CAP 0.4-0.8cm, convex, expanding to flat or the margin arched and the disc slightly depressed; grayish with a purplish cast, (dark haematite color to pale ashy pink and fading to ashy in age), pruinose at first; dry; flesh thin; tinged vinaceous. GILLS pale reddish brown (pale haematite color) broadly adnate, close to subdistant, broad; edges even. STEM 1-2.5 cm long and less than 0.1 cm thick, colored as cap and drying more purplish, with scattered remains of thin powdery veil and with a fibrillose apical zone or ring which soon disappears, top of stem pruinose; ring fibrillose, soon vanishing. ODOR and TASTE none. HABIT and HABITAT scattered on soil where a brush pile had been burned, fall. MICROSTRUCTURES spores 4-4.5 x 2.5-2.8 microns, ovoid, smooth, inamyloid.

11b Cap yellow-brown, reddish cinnamon or vinaceous (purple) brown

12a Cap yellow brown, stem about twice as long as width of the cap, cap convex to peaked or with umbo, (spores amyloid, sometimes weakly)

12b Cap color variable, usually reddish-cinnamon brown, stem about as long as width of cap, cap convex, (spores inamyloid, shorter)

................................................................................Cystodermella granulosa

CAP 1.5-3 cm broad, convex expanding to broadly convex or flat, margin appendiculate with hanging flaps of veil remnants, surface granular furfuraceous (scurfy), color variable but usually reddish-cinnamon brown, often darker in the center. ODOR and TASTE mild. GILLS whitish to pale yellowish, narrowly adnate. STEM 2-4 cm x 0.3-0.6 cm, granulose-scaly and concolorous with the cap up to the evanescent ring zone. HABIT and HABITAT solitary to gregarious on the ground in hardwood and coniferous forests. MICROSTRUCTURES spores 3.5-5 cm x 2.5-3 microns, elliptic, smooth, inamyloid. REMARKS common. There are three color variants of C. granulosum: var. occidentale is rusty-vinaceous to dull chestnut-brown with adnate to subdecurrent gills; var. adnatifolium is similar to Cystodermella cinnabarina in color but is generally not as large and the gill edges are even, not fimbriate; f. robustum attains the size of Cystodermella cinnabarina but its color is more rusty-reddish and the ring is more persistent. All are uncommon to rare.Cystodermella granulosa
Cystodermella granulosa
Steve Trudell

13a Surface even or only slightly radially wrinkled

13b Surface conspicuously radially wrinkled

 

 

REFERENCES

  1. Breheret, S., T. Talou, S. Rapior and J.M. Bessière. 1999. "Geosmin, a sesquiterpenoid compound responsible for the musty-earthy odor of Cortinarius herculeus, Cystoderma amianthinum, and C. carcharias." Mycologia 91: 117-120.
  2. Breitenbach, J., Kränzlin, F. 1995. Fungi of Switzerland Volume 4 Agarics Second Part. Edition Mykologia Lucerne.
  3. Harmaja, Harri. 2002. "Amylolepiota, Clavicybe and Cystodermella, new genera of the Agaricales". Karstenia 42: 39-48.
  4. Smith, A.H. 1949 Mushrooms in Their Natural Habitats. University of Michigan Press, Ann Arbor.
  5. Smith, Alexander H. & Rolf Singer. 1945. "A monograph on the genus Cystoderma." Papers Mich. Acad. Sci. Arts and Letters 30: 71-124.
  6. Smith, Alexander H. & Rolf Singer. 1948. "Notes on the genus Cystoderma." Mycologia 40: 454-460.

 

INDEX

    SPECIES KEY ENTRIES
   
 CYSTODERMA Fayod  
    Cystoderma amianthinum (Fr.) Fayod 9a, 3b, 13a
    Cystoderma amianthinum f. rugosoreticulatum 9b
    Cystoderma carcharias (Pers.) Fayod f. album A.H. Sm. & Singer 2a
    Cystoderma fallax A. H. Sm. & Singer 5a, 7a
    Cystoderma gruberianum A.H. Sm. 6b
 CYSTODERMELLA Harmaja  
    Cystodermella ambrosii (Bres.) Harmaja 3a
      = Cystoderma ambrosii (Bres.) A.H. Sm. & Singer  
    Cystodermella cinnabarina (Alb. & Schwein.) Harmaja 6a,10a
      = Cystoderma cinnabarinum (Secr.) Fayod  
      = Cystoderma terrei (Berk. & Broome) Harmaja  
    Cystodermella granulosa (Batsch) Harmaja 12b, 3b
      = Cystoderma granulosum (Morg.) A.H. Sm. & Singer  
    Cystodermella subpurpurea (A.H. Sm. & Singer) Harmaja 11a
      = Cystoderma subpurpureum A.H. Sm. & Singer  

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