Summary:
Lactarius resimus is a variable species but is readily recognized by the cap which is white and azonate before postmaturation changes set in, fibrils at the margin and/or edge which at times cause the edge to be bearded, the peppery taste, the relatively small spores, and the lack of projecting macrocystidia in the hymenium (Hesler(4)). The milk is scanty and white and quickly changes to yellow on exposure. Var. resimus has spore size 6-8 x 5-6 microns, and var. regalis is distinguished by larger spores 7.5-9(10) x 6-7.5(8) microns. The Hesler(4) description and Methven(2) description are for var. resimus except where noted.

Cap:
6-15cm across, deeply depressed with arched margin, becoming funnel-shaped with elevated margin; milk-white at first, azonate when young or only the margin faintly zoned, when old the margin at times conspicuously zoned with ochraceous to pale alutaceous zones; viscid to slimy, the marginal area with agglutinated fibrils, the edge naked to fringed with hairs (bearded) at least when young, the hairs when remaining when old tending to discolor yellowish to brownish, more or less bald in depression or some matted tomentum present at first, (Hesler), 6-15.5cm across, deeply depressed with arched margin, becoming funnel-shaped when old; milky white or with ochraceous zones, "azonate to faintly zoned when young, sometimes conspicuously zoned on older specimens"; viscid to glutinous, finely tomentose to nearly bald, margin bearded with coarse hairs at least when young, (Bessette), azonate or obscurely zonate, milk-white to pale yellow, often developing grayish orange stains; viscid to slimy-viscid, fibrillose becoming bald, margin bearded, (Methven)

Flesh:
thick, not brittle; white, (Hesler), white, (Bessette), up to 1.5cm thick at disc, white, quickly yellow on exposure, (Methven), MILK scanty, white but quickly changing to pale greenish yellow (Hesler), white, scanty, quickly changing to sulfur yellow, staining gills dingy yellow, (Bessette), white, quickly turning yellow on exposure, staining flesh yellow, staining white field labels yellow, (Methven)

Gills:
decurrent, crowded, narrow, forking near stem; white at first, at maturity pallid alutaceous ("pinkish buff" Ridgway(1) color), bruised areas soon staining dingy yellow, (Hesler), decurrent, crowded, often forking near stem; white becoming pinkish buff, staining dingy yellow when bruised, (Bessette), adnate to subdecurrent, close, rarely forking near stem, narrow to broad; white to pale yellow or pale orange, staining yellow where cut, not marginate, (Methven)

Stem:
6-9cm x 1-2.5cm, narrowing downward, hollow, rigid, firm; white or when old pale alutaceous like gills, not spotted or with inconspicuous, dull, unpolished, irregular spots, (Hesler), 5-9cm x 1-2.5cm, narrowing downward, hollow; white to whitish or pale yellow; sticky or dry, may be inconspicuously scrobiculate, (Bessette), 2.5-5.5cm x 1.5-3cm, round in cross-section, hollow, equal or narrowing toward base; white to pale yellow; bald, dry, not scrobiculate, white tomentum at base, (Methven)

Veil:
[none]

Odor:
not distinctive (Bessette, Methven)

Taste:
slowly peppery or mild or bitterish, (Hesler), slowly peppery (Bessette), not distinctive to slowly peppery (Methven)

Microscopic spores:
spores 6-8 x 5-6 microns, broadly elliptic, with warts and ridges, colorless, faintly amyloid, (Bessette), spores 6-8 x 5-6 microns for var. resimus, (7.5-9(10) x 6-7.5(8) microns for var. regalis), broadly elliptic, ornamentation a low broken or partial reticulum with some isolated warts and particles; basidia 4-spored; pleurocystidia: macrocystidia 36-48 x 6-9 microns, clavate to subfusoid, content refractive, colorless in KOH; cheilocystidia similar to pleurocystidia; cap cuticle a thick layer (ixocutis) of hyphae 2-4 microns wide, (Hesler for var. resimus), spores 6-8 x 5-6 microns, broadly elliptic, amyloid ornamentation a broken to partial reticulum up to 0.5 microns high; basidia 35-50 x 7.5-10.5 microns; macrocystidia 40-50(65) x 6-9 microns, subcylindric to fusoid, cheilocystidia 35-45 x 6-7.5 microns, subcylindric to fusoid; cap cuticle a thick ixocutis; stem cuticle a simple cutis with scattered projecting hyphal tips, (Methven)

Spore deposit:
white to "cartridge-buff" Ridgway(1) color, depending on thickness of deposit, (Hesler), whitish (Bessette), white to pale yellow (Methven for var. resimus), pale ochraceous (Buczacki)

Notes:
Material of var. resimus was cited from ID, OR, ON, AK, AZ, MI, TN, VT, and of var. regalis from ID, NS, ON, AK, ME, MI, NY, and WI, (Hesler). It has also been found in CA (Methven) and reported from Mexico. It has been reported from BC (Redhead(5)) and there are collections at the Pacific Forestry Centre and the University of British Columbia. The University of Washington has collections from WA, ID, AK, and MT. The New York Botanical Garden has a collection from YT.

EDIBILITY

unknown (Bessette)