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.
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.
1a Cap white or nearly so
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1b Cap red, reddish-brown, vinaceous (purple) brown, grayish with a purple cast, orange-brown, yellow-brown, or yellow
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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
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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
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4b Growing on soil, moss, humus, etc.
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5a Ring prominent, membranous, persistent
................................................................................Cystoderma fallax
5b Ring inconspicuous, as zones and patches, these soon disappearing
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6a Cap vermilion or bright orange-brown, usually larger than 3 cm broad
................................................................................Cystodermella cinnabarina
(also known as Cystoderma cinnabarinum
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
................................................................................Cystoderma fallax (See 5a)
7b Ring inconspicuous, poorly formed and soon disappearing
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8a Odor of green corn, pungent, or disagreeable
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8b Odor mild or none
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9a Cap yellow-brown, surface even or only slightly radially wrinkled
................................................................................Cystoderma amianthinum
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
................................................................................Cystodermella cinnabarina (See 6a)
10b Cap yellow-brown, reddish cinnamon or vinaceous (purple) brown, or grayish with a purplish cast, usually less than 4 cm broad
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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
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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)
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12b Cap color variable, usually reddish-cinnamon brown, stem about as long as width of cap, cap convex, (spores inamyloid, shorter)
................................................................................Cystodermella granulosa
13a Surface even or only slightly radially wrinkled
................................................................................Cystoderma amianthinum (See 9a)
13b Surface conspicuously radially wrinkled
................................................................................Cystoderma amianthinum f. rugosoreticulatum (See 9b)
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 | |
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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