Trial field key to selected CLITOCYBOID species in the Pacific Northwest

Prepared for the Pacific Northwest Key Council
By Sara Clark
Copyright © 2002-2017 Pacific Northwest Key Council

Clitocybe-like species can be confusing, but some are easy to recognize, and those will be emphasized here. A few are well-known edibles, particularly the blewit (Lepista nuda). Some have interesting odors (anise, skunk). Many different species beautify forests and other habitats in the Pacific Northwest.

Note from Ian Gibson 2017

The term “Clitocyboid” replaces “Clitocybe”, addressing the fact that many of the species described as Clitocybe by Bigelow and others have been moved to other genera. “Clitocyboid” means “resembling the general form of Clitocybe, typically with decurrent gills, fleshy-fibrous stem, and without a ring or volva”. “Omphalinoid”, on the other hand, means “resembling the general form of the genus Omphalina with broadly convex to depressed cap, decurrent or subdecurrent gills, cartilaginous stem, and without a ring or volva”. “Clitocyboid” is sometimes loosely applied to indicate agarics with decurrent gills and large fruitbodies (“omphalinoid” referring to those with decurrent gills and small fruitbodies). Mushrooms with intermediate characters could be mentioned in keys of both groups.

Several names are updated from the original key. Names for some other species are still under debate. The best name for Clitocybe dealbata ssp. sudorifica, a common lawn inhabitant, is not completely clear, but could be Clitocybe rivulosa or C. sudorifica. In early 2017, designations in the online Species Fungorum and in MycoBank differ not only for that species but for Clitocybe aeruginosa, Clitocybe atroviridis, Clitocybe candicans, Clitocybe deceptiva, Clitocybe dilatata, Clitocybe maxima, Clitocybe robusta, Lepista flaccida, and Lepista inversa. This represents almost half of the species treated here. Some of the debates are nomenclatural (regarding the validity of the names) rather than reflecting species boundaries or inheritance.

In practice many of the mushrooms presented here are easier to identify than they are to name. Although about 130 species recorded from the Pacific Northwest have had names in Clitocybe (perhaps 80 of which now have Clitocybe as their current name), the selected species here are mostly commonly identified. Three readily identifiable Clitocybe species included in the Gallery of photographs but not considered here are Clitocybe albirhiza, Clitocybe glacialis and Clitocybe sclerotoidea. Species unfamiliar to the identifier should always be checked against detailed descriptions.

Note from Ian Gibson 2011 - Two references may be useful here:

     Bigelow, H.E. 1982. North American Species of Clitocybe, Part 1. Vaduz, West Germany: J. Cramer. and 1985. North American Species of Clitocybe, Part 2. Vaduz, West Germany: J. Cramer. Comprehensive and microscopically based.

     Gregory, D. C. (2007). The genus Clitocybe of California. Masters thesis, San Francisco State University. The macroscopic key derived from this is online at http://www.mykoweb.com/CAF/keys/Clitocybe_key.pdf

KEY TO SPECIES

1a Cap blue green, grey green, or dark green

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1b Cap not having blue or green shades. Cap purple, white, orange tan, grey or brown

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2a Cap bluish green, odor of anise, gills and stem having cap color (same as cap), spore print pale pinkish buff

................................................................................C. odora

2b Cap greyish green or cap dark green without anise odor

................................................................................3

3a Cap dark green or blackish green, earthy or fishy smell, gills pale greenish, stem same color as cap or more blackish, spore print white. C. atroviridis =

................................................................................Arrhenia chlorocyanea

3b Cap grayish green and hygrophanous, odor fungoid, gills whitish to pale pinkish-buff, stem white to sordid, spore print white. C. aeruginosa =

................................................................................Lepista aeruginosa

4a (1b)  Cap basically brown or brownish grey, gills decurrent

................................................................................5

4b Cap other colors, white, purple, grey or orange to tan

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5a Cap color medium brown and cap flesh beneath center quite thick, edges relatively thin, may have odor of grape bubble gum or soda pop. Stem white with olivaceous-buff fibrils, lighter than cap color, base of stem enlarged and may be bent, gills lighter in color than cap and stem. C. clavipes =

................................................................................Ampulloclitocybe clavipes

5b Cap flesh not thick in center, cap dark brown or pale grey brown. Cap hygrophanous or not

................................................................................6

6a Cap hygrophanous with mild anise odor, taste mild, cap and stem pale grey brown, gills adnate to short decurrent, growing under conifers. Spore print pale pinkish buff

................................................................................C. deceptiva

6b Cap not hygrophanous, dark brown to olive brown, stem light olivaceous brown, gills decurrent and pale whitish to cream, cap plane to infundibuliform, (deeply depressed), striate, growing under conifers on decaying logs or other rotted woody debris. C. avellaneialba =

................................................................................Ampulloclitocybe avellaneialba

7a (4b)  Cap grey, greyish, light brownish grey or pale drab, mushroom quite large, 9-15 cm average cap width, gills whitish to cream colored, spore print pale yellow, often having an odor of skunk, growing under conifers.

................................................................................C. nebularis

7b Cap color not grey, but may be white, purple or some shade of orange or tan

................................................................................8

8a Cap with purple or violet color

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8b Cap white, or some shade of orange or tan

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9a Thin at the center of the disc, stem longer in proportion to cap width, grows in cultivated areas and compost heaps, smell absent or merely fungoid Clitocybe tarda =

................................................................................Lepista tarda

9b Cap flesh at center of the cap moderately thick to thick, odor pleasant, faintly fragrant or none

................................................................................10

10a Cap deep violet to purple at first, grows in humus under hardwoods and conifers in decaying vegetation, fresh gills have pale violet shades becoming buff to brownish in age. Spore print pink. Cap 4-12 cm, stem 3-6 cm Clitocybe nuda =

................................................................................Lepista nuda

10b Cap light violaceous or light bluish at first, grows in cedar swamps and on trash heaps, gills faintly tinged with purple, cap 6-15 cm wide, stem 5-9 cm high. Clitocybe glaucocana =

................................................................................Lepista glaucocana

11a (8b)  Cap white

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11b Cap orange or tan

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12a Growing in grass in the open (lawns and pastures). Scattered to gregarious, sometimes in arcs or rings

................................................................................C. dealbata ssp. sudorifica

12b Not growing in grass

................................................................................13

13a Growing in densely cespitose clusters in open sandy or gravelly soil, often along road sides

................................................................................C. dilatata

13b Not growing in grass or sandy gravel

................................................................................14

14a Has persistent anise odor and similar taste. Generally stem is at least half again as long as the cap is wide. Cap small 1-3 cm, watery pallid to yellowish under white canescence (pearly opaque white). Opaque to whitish as it dries

................................................................................C. fragrans

14b Anise odor lacking

................................................................................15

15a Spore print pale yellow or ivory yellow, cap flesh thick, often with pale watery areas, odor more or less disagreeable, taste rancid to sweetish. Grows in groups or clusters on leaf debris under conifers or in deciduous woods. This may actually be the white form of Clitocybe nebularis, however it grows in more various habitats than C. nebularis which suggests it may warrant designation as a separate species. These two species are similar in stature and odor.

................................................................................C. robusta

15b Spore print not pale yellow

................................................................................16

16a Spore print pale pinkish buff, smell may be pungent, or often faint, taste mild, under spruce in plantations or in rich humus in swamps (elm-ash-larch). Cap 4-13 cm wide, stem 4-8 cm tall, fairly stout in appearance. Clitocybe irina =

................................................................................Lepista irina

NOTE: Lepista irina has two varieties, var. irina which has a pale pinkish buff spore deposit, and var. luteospora with a slightly darker, more yellowish spore deposit than var. irina.

16b Mushroom of small stature. Cap 1-3 cm, stem l-3 cm high. Usually under hardwoods, sometimes under conifers in leaves or humus. Base of stem attached to leaves and with whitish mycelium and tomentum. C. candicans =

................................................................................Leucocybe candicans

17a (11b)  Mushroom fruits in the spring (June-July)

................................................................................18

17b Mushroom fruits in late July or later

................................................................................19

18a Spring fruiting, cap watery pale buff beneath canescence which creates a zonate appearance when fresh, becoming watery brown in age, base of stem with mass of white rhizoids embedded in litter. Gills adnate to short decurrent

................................................................................C. albirhiza

18b Spring fruiting, lacking rhizoids, cap brownish tan, cinnamon buff to pinkish buff, becomes infundibuliform, sub-hygrophanous, minutely squamulose on disc. Gills decurrent

................................................................................C. squamulosa

19a (17b)  Cap brick colored to terra cotta, orange cinnamon, generally cap wider than stem is tall (squat in appearance). Odor of fresh ground pepper. C. inversa =

................................................................................Lepista inversa

19b Cap not terra cotta colored, may be rusty red, tan pinkish, brownish tan, pale buff, or flesh colored

................................................................................20

20a Cap rusty red to tawny cinnamon rufous, dull orange or apricot. Cap generally almost equal to stem height C. flaccida =

................................................................................Lepista flaccida

20b Cap more in the tan-flesh color range

................................................................................21

21 There are three species treated in this key which have considerable variation within the species and consequently considerable overlap in macroscopic features. They are listed here for comparison and consideration. All of these species grow under hardwoods in leaf litter or under conifers less frequently.

1a C. maxima
When mature specimens are available this species can be recognized by its large size, vase-shaped pileus and stout stem. Cap (3) 7-15 (30) cm broad, stem 4-10 (15) cm high, 1-2.5 (3) cm thick. Flesh thin on the disk when the cap is expanded. Immature specimens can be mistaken for C. gibba var. gibba. Pinkish tan depressed cap tends to stay more or less round in shape. Another source of confusion, when using only field characters could be Infundibulicybe geotropa as both it and C. maxima are now known to depart from the typical color variations of the cap, and proportions of the stem, from those usually ascribed to each. Fading due to light exposure and presence or absence of an umbo complicate the macroscopic separation further.

1b Infundibulicybe geotropa
Flesh on the disc (center of the cap) is relatively thick when expanded, compared to C. maxima. Cap is pinkish tan, depressed. Cap 2-19 cm broad; stem 5-16 cm high and (1.5-) 2-4.5 cm thick at the top, equal or tapered up from the enlarged base.

1c C. gibba v. occidentalis
is thought of as being quite tan or pinkish tan, and funnel shaped. It can expand unevenly causing an uneven or undulating edge to the cap.

INDEX

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