Summary:
Section Fuliginellae (Smith), Section Insignes (Maas Geesteranus). Mycena tenax is distinguished by 1) its relatively large size (not as big as M. galericulata), 2) tenacious consistency, 3) gray to gray brown color, 4) gelatinous gill edges, 5) a cap and stem that are at least somewhat viscid, and 6) a strong odor and taste. The description is derived from Smith(1) except where indicated.

Cap:
1-3cm across, oval to convex, soon broadly conic or obtusely umbonate, cap center flattened or slightly depressed, margin appressed to stem at first, becoming somewhat flared; "fuscous" to "hair brown" with a pale grayish margin when young, becoming pale watery gray when old; surface bald and lubricous to subviscid, pellicle thick, tenacious, and separable, cap striate to abruptly translucent-watery disc when old, opaque when faded and somewhat sulcate [grooved]

Flesh:
pliant, tough; pallid

Gills:
adnate or slight decurrent tooth, close, 24-27 reaching stem, narrow (0.2-0.3cm); pallid to grayish

Stem:
5-7.5cm x 0.2-0.3cm, equal, hollow, tenacious consistency; color as cap (gray to brown) or paler; bald, somewhat viscid to viscid, pruinose toward top, base white strigose

Odor:
strong, disagreeable, rancid-farinaceous, or green watermelon or watermelon rind, (Smith), strong, rancid-farinaceous or like cucumber, (Castellano)

Taste:
strong, disagreeable, rancid-farinaceous, or green watermelon or watermelon rind, (Smith), strong, rancid-farinaceous or like cucumber, (Castellano)

Microscopic spores:
spores 6.5-8 x 3.5-4 microns, narrowly elliptic, pointed at one end, amyloid; basidia 4-spored, 30-34 x 5-6 microns; pleurocystidia scattered, 60-70 x 8-12 microns, narrowly fusiform to subcylindric with abruptly pointed tops, some with slightly thickened walls, cheilocystidia clavate and with finger-like projections over the top, gelatinizing as in M. vulgaris, colorless, [dimensions not given], (Smith), spores 7.2-8.1 x 4.0-4.7 microns, pip-shaped, smooth, amyloid; basidia 4-spored, 27-30 x 6.5-7 microns, narrowly clavate, with clamp connection; pleurocystidia 27-105 x 9-16 microns, fusiform with acute top, smooth, clamped; cheilocystidia 9-21 x 4.5-10 microns, "springing from a compact layer of intricately interwoven hyphae and forming a sterile band (lamellar edge homogeneous), embedded in gelatinous matter, clavate, clamped, covered with few to fairly numerous, unevenly spaced, simple to very intricately branched excrescences" 5-18 x 1.8-4.5 microns, some cystidia intermediate between pleurocystidia and cheilocystidia; hyphae of cap cuticle 1.8-3.5 microns wide, "embedded in gelatinous matter, clamped, smooth for the greater part, the uppermost ones with a few scattered excrescences" 1.8-4.5 x 1.8 microns; hyphae of cortical layer of stem 1.8-2.7 microns wide, embedded in gelatinous matter, clamped, bald for the most part but terminally with scattered excrescences 0.9-5.5 x 0.9-1.8 microns, the terminal cells widened up to 8 microns, "variously shaped and branched, often densely diverticulate", (Maas Geesteranus)

Spore deposit:
white

Notes:
Mycena tenax has been found at least in WA, OR, NS, ON, CA, and NY (Smith(1)). There are collections from BC at the Pacific Forestry Centre and the University of British Columbia. There are collections from WA and AK at the University of Washington.

EDIBILITY