1.   Lamellar edge a different color or more intensely colored than lamellar sides...................................................................................................................... 2

1.   Lamellar edge concolorous with lamellar sides or paler................................................................................................................................................................ 8

      2.   Pileus brightly colored, some shade of red, pink, yellow, or orange...................................................................................................................................... 3

      2.   Pileus coloration darker, with a distinct brown and/or gray component............................................................................................................................. 6

3.   Spores inamyloid, lamellar trama non-dextrinoid................................................................................................ sect. Oregonenses [Mycena oregonensis]

3.   Spores amyloid, lamellar trama dextrinoid......................................................................................................................................................................................... 4

      4.   Pleurocystia absent........................................................................................................................................... sect. Fragilipedes [Mycena citrinomarginata]

      4.   Pleurocystidia present......................................................................................................................................................................................................................... 5

5.   Pleurocystidia with simple apical excrescences............................................................................... sect. Luculentae subsect. Elegantes (see key below)

5.   Pleurocystidia smooth................................................................................................................................. sect. Luculentae subsect. Rosellae (see key below)

      6.   Stipe exuding a colored latex (red, reddish brown, orange) when cut or broken...............................................................................................................7

      6.   Stipe not exuding a colored latex when cut or broken...................................................................................... sect. Rubromarginatae (see key below)

7.   Stipe exuding a reddish brown to orangish latex; cortical hyphae of the stipe diverticulate with simple to furcate excrescences; the stipe not

      turning black when dried...................................................................................................................................................... sect. Sanguinolentae (see key below)

7.   Stipe exuding a dark reddish latex; cortical hyphae of the stipe smooth; the stipe

      generally turning black when dried............................................................................................................................ sect. Galactopoda [Mycena haematopus]

      8.   Spores amyloid.................................................................................................................................................................................................................................... 12

      8.   Spores inamyloid................................................................................................................................................................................................................................... 9

 9.   Stipe arising from a basal disc; pileipellis hyphae embedded in gelatinous matter, giving rise to long,

       thick-walled setae.................................................................................................................................................................... sect. Longisetae [Mycena longiseta]

 9.   Stipe not arising from a basal disc, pileipellis hyphae not embedded in gelatinous matter,

       and not giving rise to thick-walled setae............................................................................................................................................................................................10

       10.  Pileus white to some shade of brown....................................................................................... sect. Hiemales subsect. Omphaliarae (see key below)

       10.  Pileus brightly colored, some shade of red, pink, orange, or yellow................................................................................................................................. 11

11.  Stipe cortical hyphae densely diverticulate; hypodermium composed of pseudoparenchymatous cells

                                                                                   ........................................................................................................................... sect. Aciculae [Mycena acicula]

11.  Stipe cortical hyphae smooth; hypodermium composed of globose to ovoid cells (not pseudoparenchymatous)

                                                                                  .................................................................................................................................. Atheniella (see key below)

      12.  Stipe exuding a milky white to watery white latex when cut or broken.............................................................. sect. Lactipedes [Mycena galopus]

      12.  Stipe not exuding a white latex when cut or broken, but may exude a colorless hyaline fluid................................................................................. 13

13.  Pileus without separarble, gelatinous pellicle................................................................................................................................................................................. 18

13.  Pileus covered with a separable, gelationous pellicle  (pileipellis hyphae therefore embedded

       in a distinct layer of gelatinous matter)............................................................................................................................................................................................. 14

      14.  Lamellar edge not separable as an elastic-like thread; or the cheilocystidia not embedded in a gelatinous mass...........................................16

      14.  Lamellar edge separable as an elastic-like thread, or the cheilocystidia embedded in an obvious

             gelatinous mass................................................................................................................................................................................................................................. 15

15.  Stipe generally with some yellowish coloration; pleurocystidia absent .............................................................. sect. Hygrocyboideae (see key below)

15.  Stipe lacking yellowish coloration; pleurocystidia generally present or if absent, the

       cheilocystidia dendroid and highly branched apically........................................................................................................ sect. Fuliginellae (see key below)

       16.  Stipe arising from a pubescent basal disc; stipe white to whitish................................................................. sect. Basidpedes [Mycena stylobates]

       16.  Stipe not arising from basal disc; stipe not white.................................................................................................................................................................. 17

17.  Stipe partially blue to bluish green (often present only as colored fibrils at  extreme base), at

       least in young specimens, the surface not viscid or glutinous............................................................................................. sect. Amictae [Mycena amicta]

17.  Stipe lacking blue to bluish green tones, the surface viscid to glutinous when moist....................................... sect. Insignes [Mycena quinaltensis]

       18.  Spores ellipsoid to amygdaliform, or cylindric........................................................................................................................................................................ 20

       18.  Spores globose to subglobose...................................................................................................................................................................................................... 19

19.  Basidiomes corticolous on coniferous or hardwood trees................................................................................................ sect. Supinae [Mycena corticalis]

19.  Basidiomes growing on leaves and other herbaceous debris.............................................................................. sect. Polyadelphia [Mycena culmigena]

       20.  Pileus surface distinctly granular to furfuraceous or floccose, whitish to grayish; hyphae of the 

              pileipellis giving rise to inflated,±globose to pyriform terminal cells  which are covered with short 

              diverticula or spinules..................................................................................................................................................... sect. Sacchariferae (see key below)

       20.  Pileus surface not distinctly granular to furfuraceous or floccose, or if so, pileipellis hyphae

               lacking inflated, ornamented terminal cells........................................................................................................................................................................... 21

21.  Hyphae of the pileipellis and stipe not at the same time smooth, one or both covered

       with some form of excrescence........................................................................................................................................................................................................... 25

21.  Hyphae of the pileipellis and stipe smooth, or with very rare, scattered excrescences..................................................................................................... 22

       22.  Cheilocystidia covered with excrescences...................................................................................................................... sect. Mycena [Mycena maculata]

       22.  Cheilocystidia smooth..................................................................................................................................................................................................................... 23

23.  Basidiomes lignicolous, typically growing in dense caesptiose clusters; the lower half

       of the stipe clothed in thick, whitish tomentum........................................................................................................ sect. Fragilipiedes [Mycena overholtsii]

23.  Basidiomes lignicolous or terrestrial, typically not growing in dense caespitose clusters;

       the stipe lacking thick whitish tomentum......................................................................................................................................................................................... 24

       24.  Basidiomes frequently with purplish, violaceous, or pinkish coloration; spores ellipsoid

              and relatively narrow (< 5µm); stipe cortical hyphae not embedded in gelatinous matter

                                                   ................................................................................................................................. sect. Calodontes subsect. Purae [Mycena pura]

       24.  Basidiomes typically grayish to brownish in color; spores broadly ellipsoid (> 6µm);

              stipe cortical hyphae embedded in gelatinous matter............................................................... sect. Fragilipedes [Mycena excisa sensu A.H. Sm.]

25.  Cheilocystidia entirely to partially covered with few to numerous, simple to branched, cylindric, 

       coarse, or inflated excrescences (these forms occasionally intermixed with smooth cheilocystidia)........................................................................... 27

25.  Cheilocystidia smooth; rounded or tapered apically, or forming a mucronate/rostrate apex

       or elongated neck, occasionally with more than one apical tip or necks................................................................................................................................ 26

       26.  Cheilocystidia and pleurocystidia often greatly protruding from lamellar edges and sides; abundant laticiferous hyphae

              present in stipe tissues, containing granular or oleiferous contents.................................................................. sect. Lactipedes [Mycena galopus]

       26.  Cheilocystidia and pleurocystidia not greatly protruding; stipe tissues

               lacking abundant laticiferous hyphae........................................................................................................................... sect. Fragilipedes (see key below)

27.  Cheilocystidia embedded in a removable, gelatinous lamellar edge; the pileipellis a 

       hymeniform monolayer of pedicillate, lentiform to clavate cells................................................................................... sect. Testudini [Mycena gaultheri]

27.  Cheilocystidia not embedded in a removable, gelatinous layer; the pileipelis a cutis of typically 

       narrow, cylindric hyphae, which may be smooth or covered with excrescences................................................................................................................. 28

       28.  Pleurocystidia, and some proportion of the cheilocystidia, fusiform to lagenifom in shape and 

             centrally covered with few to numerous, evenly or unevenly spaced, simple excrescences;

             more rarely smooth; often with slightly thickened walls........................................................................................ sect. Intermediae [Mycena latifolia]

       28.  Pleurocystidia and cheilocystidia not as above....................................................................................................................................................................... 29

29.  Cheilocystidia covered with ±unevenly spaced, short to quite long, cylindric to coarse,

       typically branching excrescences; and/or apically branching or passing into few to numerous,

       cylindric to coarse excrescences/projections................................................................................................................................................................................. 31

29.  Cheilocystidia covered with ±evenly spaced, typically short (<10µm) and simple, rarely branched excrescences................................................... 30

       30.  Stipe surface (and in some instances the pileus) viscid to glutinous when wet; pileipellis

              and stipe cortical hyphae embedded in gelatinous matter............................................................................... sect. Cinerellae [Mycena clavicularis]

       30.  Stipe surface not viscid to glutinous when wet; pileipellis and stipe cortical hyphae

              not embedded in gelatinous matter...................................................................................................................................... sect. Filipedes (see key below)

31.  Cheilocystidia apically passing into one or several, cylindric, often furcate necks;  or giving rise 

       apically and/or somewhat laterally to one or several, cylindric, often branching excrescences; 

       generally intermixed with smooth, often fusoid to lageniform cheilocystidia........................................................... sect. Fragilipedes (see key below)

31.  Cheilocystidia entirely or apically covered with, or branching into, few to numerous,

       simple to branched, cylindric to quite coarse and/or inflated excrescences; rarely intermixed

       with smooth, basidiole-like cheilocystidia........................................................................................................................................................................................ 32

       32.  Basidiomes typically larger and more robust, the majority of mature pilei  20 mm

              or greater in diameter; not omphalinoid................................................................................................................................ sect. Mycena (see key below)

       32.  Basidiomes typically smaller and more fragile, the majority of mature pilei typically

              less than 20 mm in diameter; often omphalinoid................................................................................................................................................................... 33

33.  Pileipellis hyphae not typically embedded in a gelatinous layer (if so then pleurocystidia present);

       pleurocystidia present or absent................................................................................................................................................. sect. Cinerellae (see key below)

33.  Pileipellis hyphae embedded in a thin to quite thick subgelatinous layer; pleurocystidia absent.............................. sect. Mycena [Mycena pusilla]

 

Key to the CA species of Atheniella

1.   Pileus at first  red, orange-red, bright pinkish red, (rarely white), pallescent or fading to orange to yellowish orange;

      margins fading to paler   or white; stipe delicately pink, white or yellowish; hymenial cystidia of dried specimens without

      exudative droplet at apex........................................................................................................................................................................................... Atheniella adonis

1.   Pileus at first deep orange to orangish red, fading to pale orange or bright yellow at the disk; margins fading to pale

      orange, pale yellowish and generally whitish eventually; stipe yellow to yellowish white, fading to white; hymenial cystidia

      of dried specimens generally with exudative droplet at apex............................................................................................................ Atheniella aurantiidisca

 

Key to the California species of section Cinerellae

1.  Cheilocystidia covered with ± evenly spaced, cylindric to coarse, generally simple excrescences;

     the stipe viscid to glutinous when moist............................................................................................................................................................ Mycena clavicularis

1.  Cheilocystidia with few to numerous, ± unevenly spaced, cylindric to coarse, simple to branched

     and/or contorted excrescences; more rarely lacking excrescences althogether; the stipe dry, moist,

     or viscid............................................................................................................................................................................................................................................................ 2

     2.  Cheilocystidia with 2 or more very coarse, contorted, often branched excrescences; more rarely lacking

          excrescences altogether and then ±clavate; the hypodermium underlain by a thick layer of non-dextrinoid,

          distinctly gelatinous hyphae........................................................................................................................................................................... Mycena subconcolor

     2.  Cheilocystidia with one to numerous, cylindric to coarse, simple or branching, often contorted excrescences;

          the hypodermium not underlain by a thick layer of gelatinous hyphae................................................................................................................................. 3

3.  Cheilocystidia with one to several, short to quite long (-22.4) and highly branched, often coarse and

     contorted excrescences; pleurocystidia generally present, similar to cheilocystidia; corticolous on

     living madrone trees (Arbutus menziesii); color of pileus and stipe with distinct brown component.......................................... Mycena madronicola

3.  Cheilocystidia with few to numerous, generally short (-10.4), simple to branched, cylindric or coarse

     excrescences; pleurocystidia absent; growing on needles, leaves, and other debris of conifers and

     hardwoods, or among moss; color of the pileus and stipe with a distinct grayish to grayish brown

     component........................................................................................................................................................................................................................ Mycena cinerella

 

Key to the California species of section Filipedes

1.  Pileus and stipe with distinct yellowish tones; stipe base covered with yellow to yellowish green

     fibrils; lamellar edge often pale yellow to yellowish green................................................................................................................... Mycena chloranthoides

1.  Pileus and stipe generally lacking distinct yellowish tones or only developing them in age; stipe

     base covered with whitish to whitish gray fibrils; lamellar edge not yellow to yellowish green.......................................................................................... 2

     2.  Cheilocystidia covered with unevenly spaced, simple to branched excrescences........................................................................ Mycena atroalboides

     2.  Cheilocystidia covered with ±evenly spaced, generally simple, narrow excrescences..................................................................................................... 3

3.  Cheilocystidia with numerous excrescences, generally with a narrowed or stipitate base, not

     forming a thick edge, often intermixed with basidia; the stipe cortical hyphae not giving rise to

     numerous terminal cells, any present generally similar to hyphae or slightly broader; pileus margin

     not extending beyond the lamellae; the lamellae often developing incarnate tones in age....................................................................... Mycena metata

3.  Cheilocystidia with relatively few excrescences, the majority of which are sessile, forming a thick,

     sterile lamellar edge; the stipe cortical hyphae giving rise to numerous, generally clavate terminal

     cells which are entirely or apically densely covered with short simple excrescences; the margin of

     the pileus often extending beyond the lamellae; the lamellae not developing incarnate tones in age................................................... Mycena filopes

 

Key to the CA species of section Fragilipedes

1.  Basidiomes large and robust, forming dense cespitose clusters on decaying wood; the stipe bases

    clothed in a thick, whitish tomentum..................................................................................................................................................................... Mycena overholtsii

1.  Basidiomes not large and robust, not forming dense cespitose clusters on wood; the stipe bases

     with or without coarse fibrils, but not clothed in a thick whitish tomentum.............................................................................................................................. 2

     2.  The pileipellis and stipe cortical hyphae both ±smooth and embedded in gelatinous matter........................................................................................ 3

     2.  The pileipellis and stipe cortical hyphae not both at the same time smooth and embedded in gelatinous matter 4

3.  Pleurocystidia present; basidiospores greater than 10 X 5.5 μm...........................................................................................Mycena excisa sensu A. H. Sm.

3.  Pleurocystidia absent; basidiospores less than 8.5 X 4.5 μm.......................................................................................................................... Mycena laevigata

    4.  Basidiomes lacking clamp connections (or with pseudoclamps).............................................................................................................................................. 5

    4.  Basidiomes with clamp connections.................................................................................................................................................................................................. 6

5.  Cheilocystidia utriform to lageniform or clavate, smooth................................................................................................................................. Mycena deceptor

5.  Cheilocystidia lageniform to clavate or ±irregular, with one or more apical necks and/or giving rise to excrescences...................... Mycena vitilis

     6.  Basidiomes typically with some yellowish color to the pileus, lamellar edges and/or sides, or

          stipe, more rarely entirely white........................................................................................................................................................... Mycena citrinomarginata

     6.  Basidiomes typically lacking yellowish coloration, generally grayish to brownish (if entirely white,                      

          then growing on twigs of Sequoia sempervirens)......................................................................................................................................................................... 7

7.  Basidiomes typically growing on or near ferns and fern debris; the stipe pale ash gray to white...................................................... Mycena fragillima

7.  Basidiomes typically growing on wood or woody debris; the stipe darker grayish to grayish brown           

     (rarely white, and if so then growing on wood of Sequoia sempervirens).................................................................................................................................. 8

     8.  Stipe cortical hyphae typically with large, inflated terminal cells and/or narrower cells giving rise                         

          to one or more inflated, often quite long excrescence........................................................................................................................... Mycena leptocephala

     8.  Stipe cortical hyphae lacking large, inflated terminal cells, those present (if any) similar to

          hyphae and/or covered with narrow excrescences...................................................................................................................................................................... 9

9.  Pileus of young basidiocarps distinctly minutely pruinose, mature basidiocarps often retaining some         

     pruinosity; ~12 lamellae reaching the stipe; somewhat diminutive species growing on dead branches

     and trunks of fallen or standing conifers, rarely hardwoods; rarely entirely white and then growing on

     wood of Sequoia sempervirens.................................................................................................................................................................................. Mycena subcana

9.  Pileus of young basidiocarps glabrous or canescent, if pruinose then soon glabrescent; 13 or more lamellae

     reaching the stipe; more robust species typically growing on decaying wood and debris of conifers and hardwoods............................................. 10

     10.  Pileus and stipe surface initially covered with a bluish sheen due to presence of hoary bloom;

            basidiospores up to 10.4 μm in length; odor indistinct, not alkaline........................................................................................................ Mycena alnicola

     10.  Pileus and stipe lacking bluish sheen; basidiospores often larger, up to 12.8 (-14.4) μm in

            length in some species; odor alkaline, pleasant, or indistinct.............................................................................................................................................. 11

11.  Cheilocystidia variable, typically fusoid and intermixed with broadlyclavate to obovoid forms..................................................... Mycena aff. murina

11.  Cheilocystidia fusiform, lageniform, or irregular-clavate, not intermixed wit broadly-clavate to obovoid forms...................................................... 12

       12.  Cheilocystidia fusoid-ventricose to lageniform, typically with a single elongated neck, rarely

              with 2-3 simple apical excrescences; pleurocystidia often present, similar to cheilocystidia..................................................... Mycena abramsii

       12.  Cheilocystidia irregular-clavate to ±fusiform or ±lageniform, typically narrowed apically into one              

              to several, cylindric to coarse, simple or branched excrescences; pleurocystidia absent.................................................. Mycena alcaliniformis

 

Key to the CA species of section Fuliginellae

1.  Lamellae ascending-adnate, never arcuate or decurrent; pleurocystidia present, fusiform to

     subcylindrical......................................................................................................................................................................................................................... Mycena tenax

1.  Lamellae adnate, becoming arcuate to decurrent with age; pleurocystidia absent.................................................................................... Mycena vulgaris

 

Key to the California species of section Hiemales subsection Omphaliariae

1.  Spores globose to subglobose, or broadly ellipsoid; basidia 4-spored; growing on the wood of

     Thuja occidentalis (cedar) or other conifers............................................................................................................................................................. Mycena clavata

1.  Spores ellipsoid to amygdaliform; basidia generally 2-spored; growing on the trunks or woody

     debris of hardwoods and conifers...................................................................................................................................................................... Phloeomana speirea

​

Key to the California species of section Hygrocyboideae

1.  Pileus typically with deep olivaceous coloration at maturity; the lower portion of the stipe reddish to

     reddish brown; cheilocystidia apically narrowed into one or two, tapered and somewhat pointed

     excrescences; basidiomes lignicolous on conifer logs and woody debris, associated with melting

     snow banks in the Sierra Nevada and Cascade Ranges during the spring and summer months........................................................... Mycena nivicola

1.  Pileus typically lacking deep olivaceous colors, typically yellowish to yellowish white or yellowish

     gray; the lower portion of the stipe with or without reddish stains in age; cheilocystidia covered with

     few to numerous, simple to branched excrescences; basidiomes not associated with melting snow

     banks................................................................................................................................................................................................................................................................. 2

     2.    Basidiomes with a rancid-farinaceous taste; pileus, tissues, and stipe base

            developing sordid brownish stains or coloration in age................................................................................................. Mycena epipterygia var. viscosa

     2.    Basidiomes lacking rancid-farinaceous taste; pileus and tissues not developing

            sordid brownish stains or coloration............................................................................................................................. Mycena epipterygia var. epipterygia

 

Key to the California species of section Luculentae

1.  Pileus with distinctive pinkish to pale reddish tones; lamellar sides often developing

     punctate reddish dots in age; pleurocystidia smooth........................................................................................................ Mycena rosella [subsect. Rosellae]

1.  Pileus with distinctive reddish orange, orangish or yellowish tones; lamellar sides not developing

     punctate dots in age; pleurocystidia covered with excrescences.................................................................................................................................................. 2

     2.    Pileus disk brownish, olivaceous, or brownish orange, the margins orangish to yellowish-

            orange; basidiomes generally not retaining bright coloration upon drying............................... Mycena aurantiomarginata [subsect. Elegantes]

     2.    Piles lacking brownish or olivaceous tones, entirely orangish red, orangish or yellowish;

            basidiomes retaining bright coloration upon drying out........................................................................... Mycena strobilinoides [subsect. Elegantes]

 

Key to California species of section Mycena

1.  Basidiomes typically growing in troops on fallen conifer needles or among mosses; the stipe base

     not forming a pseudorhiza ........................................................................................................................................................................................................................ 2

1.  Basidiomes solitary, gregarious, or in large caespitose clusters; lignicolous on decaying wood

     and/or the bark of living trees; the stipe base often forming a pseudorhiza............................................................................................................................. 3

     2.  Basidiomes small (5-10 mm diam); the pileipellis embedded in a thick gelatinous layer (up to 65

          µm thick); lacking pleurocystidia.............................................................................................................................................................................. Mycena pusilla

     2.  Basidiomes larger (20-35 mm diam); the pileipellis not embbeded in a thick gelatinous layer;

          pleurocystidia present............................................................................................................................................................................................. Mycena piceicola

3.  Lamellae generally developing reddish-brown spots or stains in age; basidiomes typically

     growing in caespitose clusters; the pileipellis and stipe cortical hyphae smooth, or with rare,

     scattered excrescences............................................................................................................................................................................................... Mycena maculata

3.  Lamellae not developing reddish-brown spots or stains in age; basidiomes solitary, gregarious,

     or in caespitose clusters; the pileipellis and stipe cortical hyphae densely covered with excrescences..................................... Mycena galericulata

 

Key to the California species of section Rubromarginatae

1.  Lamellar sides becoming punctate with pinkish, reddish, or violaceous brown dots (at least when

     dried); pleurocystidia abundant and protruding.............................................................................................................................................. Mycena capillaripes

1.  Lamellar sides without punctate dots, pleurocystidia absent......................................................................................................................................................... 2

     2.  Pileus and stipe with distinct purple to violaceous tones; pileipellis and stipe cortical hyphae gelatinized or embedded in gelatinous

          matter................................................................................................................................................................................................................ Mycena purpureofusca

    2.  Plieus and stipe with distinct red to reddish brown tones; pileipellis and stipe cortical hyphae not gelatinized or embedded

          in gelatinous matter ............................................................................................................................................................................................ Mycena bulliformis

 

Key to the California species of section Sanquinolentae

1.  Cheilocystidia generally fusiform, typically apically narrowed into one or more necks, acute, smooth

     or with occasional small diverticula; generally growing on the decayed wood or debris of conifers........................................ Mycena sanguinolenta

1. Cheilocstidia contorted-clavate to irregular in shape, with irregular knob-like diverticula and/or

     numerous long, cylindrical apical projections; generally growing on the leaves and fruits of Quercus species

                                     ................................................................................................................................................................................................. Mycena californiensis

 

Key to the California members of section Sacchariferae

1.  Stipe arising from a basal disc; lamellae tending to secede from the stipe and form a

     pseudocollarium; basidia 2-spored........................................................................................................................................................................ Mycena tenerrima

1.  Stipe not arising from a basal disk; lamellae not forming a pseudocollarium; basidia typically 4

     spored......................................................................................................................................................................................................................... Mycena alphitophora