Summary:
Subgenus Russularia. Lactarius rufus is told from other brownish reddish Lactarius species by the very peppery taste, the unchanging, unstaining white milk, the habitat under conifers, and microscopically a cap cuticle that is a simple cutis. According to Neuhoff''s detailed 1956 description it features pale yellow spores, a promptly strongly acrid [peppery] taste, flesh that becomes olivaceous to some degree with FeSO4, and whitish gills with a grayish flesh tone, but in North American material, the spore deposit may be white, the acrid taste may be delayed, the FeSO4 reaction may be absent, and there are variations in final gill color. Var. parvus is darker in color when wet and habitat seems to be confined to conifer logs - it was described from Idaho.

Cap:
3-10(15)cm across, convex to flat, disc depressed, umbonate or not, margin incurved to decurved [downcurved]; azonate, brownish red to reddish brown; bald, dry to moist, margin bald, crenate [scalloped], (Methven), 4-12cm across, broadly convex becoming flat or depressed; dark brick-red to bay-red or reddish brown; smooth, usually not viscid, margin naked, (Arora), 3-12cm across, "broadly convex with a shallow depression and sometimes a small umbo and an incurved margin, becoming flatter then broadly funnel-shaped; yellowish to brick-red cinnamon becoming paler in age; hoary becoming dull and dry", (Phillips), sometimes wrinkled when old, (Trudell)

Flesh:
up to 1cm thick at disc; pale orange, not staining on exposure, (Methven), rather fragile; dingy reddish, (Arora), whitish to pale pinky brown, (Phillips), MILK "white, unchanging on exposure, staining field labels pale yellow", (Methven), white, unchanging, (Arora), plentiful; milk-white, unchanging, (Phillips), scanty to abundant, white, unchanging, (Hesler)

Gills:
"adnate to subdecurrent, close to subdistant, narrow", forking near stem; pale orange, not marginate, not staining where cut, (Methven), adnate to slightly decurrent, crowded; whitish when young, flushed reddish when old, (Arora), "adnate to short decurrent, crowded, narrow; whitish becoming pale pinky-yellow to pinky-tan", (Phillips)

Stem:
3-9cm x 1-2(3)cm, equal or narrowing toward the base, round in cross-section; brownish orange to reddish brown; dry, bald, not scrobiculate, light orange tomentum at base, (Methven), 4-11cm x 1-1.5cm, equal, stuffed or hollow, rigid but rather fragile; more or less colored like cap, (Arora), 5-11cm x 0.9-1.7cm, slightly widened toward base, stuffed; colored as cap except for whitish base; "powdery and finely downy becoming dry", (Phillips), pinkish brown to brownish orange, but often lower and upper parts pale, (Trudell)

Odor:
not distinctive (Methven), mild, (Arora), very slight, developing an odor like bouillon cubes as it dries, (Phillips)

Taste:
strongly peppery (Methven), strongly but often latently peppery (Arora), immediately very peppery (Phillips), after about a minute of chewing the burning sensation begins (Ammirati)

Microscopic spores:
spores 7-9.5 x 6-7 microns, broadly elliptic, amyloid ornamentation a partial reticulum up to 0.5 microns high; basidia 35-45 x 7.5-9 microns; pleurocystidia: macrocystidia 35-60 x 6-9 microns, fusoid to fusoid-ventricose, often with one or more subapical constrictions, cheilocystidia 25-35 x 4.5-7.5 microns, cylindric; cap cuticle a simple cutis; stem cuticle a simple cutis, (Methven), spores 7.5-11 x 5-7.5 microns, elliptic, with amyloid warts and ridges, (Arora), spores 7.5-10 x 6-7.5 microns, ornamented with ridges forming a partial reticulum and isolated warts, prominences about 0.5 microns high, (Phillips), spores 8.5-10.5(12) x 6-7.5(8) microns in variant fitting European material mostly closely (but 7-9 x 5-6.5 microns in the common variant in sphagnum bogs), broadly elliptic, ornamentation predominantly as ridges with a few isolated warts, ridges forming a partial reticulum, prominences +/- 0.5 microns high; basidia 4-spored, 37-40 x 8-11 microns; pleurocystidia: macrocystidia 42-67 x 8-10 microns, "fusoid-ventricose, acuminate, content spangled, embedded in hymenium to slightly projecting", pseudocystidia rare to apparently absent; cheilocystidia 22-30 x 5-7 microns, "cylindric, apex obtuse to subacute", (Hesler(4) for collection that best suited European material)

Spore deposit:
white to pale yellow in mass (Methven), pale yellowish (Arora), cream with a pale pinky tinge (Phillips)

Notes:
Material was cited for var. rufus and its variants from WA, OR, ID, NS, ON, CO, MI, WI, WY, and Switzerland. L. rufus has been reported from CA (Arora(1)), and BC (in Redhead(5)).

EDIBILITY

not recommended (canned in Scandinavia, but North American variants not tested and it may be poisonous raw), (Arora), poisonous (Phillips)