Summary:
{See also Viscid Gray-brown Lactarius Table.} Lactarius pseudomucidus is distinguished by the slimy dark grayish brown cap, the slimy stem that is colored like the cap or paler (gray), and the white milk. Other features include adnate to decurrent gills that are whitish, spotting yellowish to tan to brown from milk, a peppery taste, and broadly elliptic spores with amyloid ornamentation in the form of a more or less distinct reticulum. Lactarius pseudomucidus is common in the Pacific Northwest.

Cap:
3-8(10)cm across, broadly convex becoming flat or depressed; blackish-brown to dark gray, without zones; "smooth, viscid (with a thick layer of slime when moist)", margin naked, (Arora), (3)4-10(12)cm across, flat-convex with inrolled margin becoming shallowly depressed to broadly funnel-shaped, margin often wavy or crenate [scalloped]; charcoal-fuscous to drab-gray and rather evenly colored overall; bald, covered with a thick layer of slime, margin opaque or striatulate [finely striate], (Hesler), 2-7cm across, grayish brown to brown (fading to light brown), not zoned; bald, viscid to slimy-viscid, margin bald, "even to irregularly crenate, translucent-striate or striate", (Methven)

Flesh:
thin, fragile; grayish, (Arora); thin and lax; grayish, in stem gray to pale fuscous, (Hesler), up to 0.5cm thick at disc, white to gray, unstaining on exposure, (Methven), MILK "white, unchanging, but may stain gills tan to brownish, gray, or olive-gray", (Arora), milk-white but thin (not whey-like), when old "spotting gills yellowish to tan to brown but not changing readily" (yellowish dried on gills), (Hesler), white to whey-like, drying yellow on the gills, staining white field labels yellow, staining the gills brown where cut, (Methven)

Gills:
adnate to decurrent; "white or tinged gray, sometimes discolored (brownish, etc.) in age", (Arora), adnate to short-decurrent, "close becoming subdistant, narrow to moderately broad"; white with cinereous [ash-gray] edge, spotting yellowish to tan to brown from milk, (Hesler), "adnate to subdecurrent, close to distant", narrow to broad, thin, forking near stem; white to yellow, staining brown where cut, edges colored as faces, (Methven), "strikingly white with a grayish or yellowish tint", staining "brownish when cut or bruised"

Stem:
4-10cm x 0.5-1cm, fragile, usually thicker in lower part; "evenly colored like cap or paler (gray)"; smooth, without spots, very slimy when wet, (Arora), (3)4-9(11)cm x 0.5-1(1.5)cm, widening downward, "soon hollow and exceedingly fragile"; fuscous to "benzo-brown" [Ridgway(1) color] or paler gray; very slimy when fresh, (Hesler), 4-8.5cm x 0.5-1.5cm, round in cross-section, equal or widened toward base, stuffed to hollow; light brown, often paler at base, fading to grayish orange; bald, viscid to slimy-viscid, fibrillose-streaked, not scrobiculate, (Methven)

Veil:
[none]

Odor:
slight (Hesler), not distinctive (Methven)

Taste:
slowly peppery (Arora), slowly peppery or bitterish then peppery, (Hesler), peppery (Methven)

Microscopic spores:
spores 7-9 x 6-7 microns, broadly elliptic, with amyloid ridges, (Arora), spores 7-9 x 6-7 microns, broadly elliptic, [amyloid] ornamentation "in the form of heavy bands with branches all together a more or less distinct reticulum", prominences 0.5-1.2 microns; basidia 4-spored, clavate; pleurocystidia: macrocystidia abundant, 60-110 x 7-14 microns, "elongate-fusoid with a long taper to a pointed apex"; cheilocystidia similar to macrocystidia but smaller; cap cuticle a basal layer of interwoven hyphae 3-6 microns wide, this layer giving rise to an ixotrichoderm of hyphae 1.5-3 microns wide and 100-200 microns long, colorless, the layer collapsing to form an ixolattice; stem cuticle an ixocutis (possibly an ixotrichoderm when young), the hyphae colorless, 1.5-3 microns wide and +/- appressed, (Hesler), spores 7-9 x 6-7 microns, broadly elliptic to elliptic, "amyloid ornamentation a partial to nearly complete reticulum" 0.5-1 micron high; basidia 35-55 x 6-10.5 microns, macrocystidia 50-95 x 7.5-10.5 microns, fusoid; cheilocystidia 30-50 x 6-9 microns, fusoid; cap cuticle an ixotrichoderm arising from an interwoven layer of filamentous hyphae, dextrinoid debris and incrustations present; stem cuticle an ixocutis to ixolattice, (Methven)

Spore deposit:
white (Arora, Hesler), white to pale yellow in mass (Methven)

Notes:
Material was cited with the original description by Hesler(4) from WA, OR, ID, AK, and CA. It has been reported by Gamiet(2) from BC, and there are collections from BC at the Pacific Forestry Centre and the University of British Columbia.

EDIBILITY

unknown (Arora)