Summary:
Section Lactipedes (Smith), Section Galactopoda (Maas Geesteranus). Mycena haematopus is distinguished by 1) dull-red to reddish-brown colors, 2) a grayish-pruinose cap and stem when young, 3) a scalloped cap margin, 4) dark blood-red juice which exudes from the flesh or stem when it is cut, 5) a stem base with coarse hairs, 6) habitat on wood (often in cespitose tufts), and 7) fusoid cystidia, (Smith(1)). Smith calls it the commonest and most easily recognized species in the genus.

Cap:
1-3.5(5)cm across, "oval to bell-shaped when young, with the margin often extending beyond the gills", when old sometimes convex or flat with an umbo and uplifted margin; reddish to vinaceous brown to reddish brown or pinkish brown, margin often paler (vinaceous gray); smooth, not viscid, striate at maturity when moist, margin often scalloped when old, (Arora), 1-3.5(5)cm across, obtusely bell-shaped or broadly conic, sometimes convex, sometimes sharply conic, when old flat or with recurved [upcurved] margin and sharp or blunt umbo, margin usually with a sterile band that becomes torn or crenate [scalloped]; dark reddish brown on the disc and paler grayish vinaceous toward margin, margin whitish in some and the disc pale dingy reddish brown, often stained dark dingy reddish brown when old; "at first appearing dry and covered with a dense pruinose coating", soon polished and moist, translucent-striate at maturity, sometimes becoming sulcate [grooved] when old, (Smith), hygrophanous, fairly dark sepia brown at center, without or with a vinaceous shade, pinkish brown or pale purplish brown to brownish incarnate further outward, dingy yellowish toward margin, darkening and sometimes becoming stained with purplish spots when old, drying pinkish white, (Maas Geesteranus)

Flesh:
thin; "exuding a dark red juice when cut", (Arora), thin, fragile; "grayish vinaceous or pallid, exuding a dark blood-red latex when cut", (Smith)

Gills:
"attached (usually adnate or adnexed), fairly close"; "pallid, often developing reddish stains", edges white or in one form reddish, (Arora), narrowly adnate, ascending, close to subdistant, 20-30 reaching stem, narrow to moderately broad, 2-3 tiers of subgills; whitish or grayish vinaceous, soon stained dingy reddish brown, edges pallid or whitish; edges flocculose, (Smith), broadly adnate, decurrent with a tooth, ascending, 15-26 reaching stem, up to 0.35cm broad, ventricose, becoming interveined; at first whitish, then pale flesh-color, brownish flesh-color or pale vinaceous, becoming purple-stained when old, the edges colored as faces or brownish to purplish brown near margin of cap, (Maas Geesteranus)

Stem:
3-8(14)cm x 0.1-0.3cm, equal, fragile; dull reddish or reddish brown, or sometimes pallid; smooth, "base with coarse hairs, exuding a dark red juice when cut", (Arora), (3)4-8(14)cm x 0.1-0.2(0.3)cm, equal, rigid, fragile, hollow; upper part covered by dense, pallid to pale cinnamon drab pruinose coating, becoming polished when old, "exuding a dark blood-red latex when broken", base strigose, (Smith), equal or widening slightly in lower part, straight or curved, round to flattened in cross-section, (Maas Geesteranus)

Odor:
not distinctive (Smith), not distinct or fungoid or perhaps somewhat radish-like, (Maas Geesteranus)

Taste:
mild to bitterish (Smith), absent or bitterish (Maas Geesteranus)

Microscopic spores:
spores 7-11 x 5-7 microns, elliptic, smooth, amyloid, (Arora), spores 8-11 x 5-7 microns, broadly elliptic, amyloid; basidia 4-spored; pleurocystidia rare to abundant, similar to cheilocystidia, cheilocystidia very numerous, 33-60(80) x 9-12 microns, "fusoid-ventricose, apices acute, sometimes forked, hyaline", (Smith), caulocystidia 20-55 x 3.5-12.5 microns, "generally occurring densely clustered, easily collapsed, clavate to irregularly shaped, clamped, branched to very coarsely diverticulate", (Maas Geesteranus)

Spore deposit:
white (Arora)

Notes:
It is found at least in BC, WA, OR, and ID (Smith). Smith also examined collections from MB, NS, ON, AL, CA, IL, NC, NY, MI, MO, OH, PA, and WI. Maas Geesteranus says it is known from Europe (including the Netherlands), US, Canada, and Japan, and Breitenbach(3) includes also Switzerland, North Africa, and Australia.

EDIBILITY

yes according to some sources, (Arora)

Synonyms and Alternate Names:
Mycena hematopoda (Fr.) Quel.