Summary:
{See also Blackening Russulas Table.} Clade Compacta. Russula albonigra is easily identified by its hard whitish cap and stem and the blackening (without reddening first) of all parts when old or when handled, (Arora). The cap surface is dry, matte, and unpeeling. Gills are close to crowded and spore deposit is white. Taste is mild or slowly peppery or slightly bitter or with a slight taste of menthol. Diagnostic characteristics are color change directly to blackish, the relatively thin and undifferentiated cap cuticle, and the low spore ornamentation, (Shaffer).

Cap:
6-17cm across, "pallid when young, soon becoming brownish then black"; "matte, margin even, unpeeling", (Woo), 7-20(25)cm across, broadly convex or centrally depressed becoming broadly depressed when old; at first white, soon becoming grayish or blackish brown and finally entirely black; "dry to slightly viscid, sometimes polished", smooth, margin not striate, (Arora), 6-17cm or more, broadly convex with incurved margin becoming flat-depressed, with margin raised when old and the cap then funnel-shaped; when young whitish overall, gradually becoming brown to fuscous or black, when bruised usually browning or blackening directly, occasionally passing through a brownish vinaceous stage; "subviscid to merely moist at first, soon dry", matte, bald, at times areolate-rimose when old, "with cuticle not or scarcely separable and margin not striate", (Shaffer), 6-12cm across, "convex, often umbilicate, eventually with applanate margin and widely depressed center, or entirely concave, often irregular"; "white, becoming cinereous toward margin, eventually blackish or fuscidulous"; slightly viscid when young during rain but drying very rapidly and quite opaque, smooth, "subtomentose in center and at first on extreme margin", (Singer)

Flesh:
hard; "white rapidly darkening when bruised or cut to brownish gray, then black", (Woo), "thick, crisp, brittle"; "white, bruising gray and then black", (Arora), thick, 1.2-2cm, hard, white, when cut soon becoming gray-brown to fuscous or black, (Shaffer), firm and compact, white or whitish, definitely never reddening at all, blackening directly on exposure within 1 minute when fresh, (Singer)

Gills:
close to crowded, forked at stem, regular subgills; "whitish, blackening when injured", (Woo), "adnate to slightly decurrent, close to rather well-spaced, thick, brittle, usually alternating long and short"; creamy white staining gray or black, often entirely black when old, (Arora), adnate to decurrent, close to subcrowded, subgills numerous, 1-4 between each pair of gills, gills narrow to moderately broad, 0.4-0.9cm broad, acute near margin, sometimes forked at stem and outward, intervenose or not; white to pale yellow ("light cartridge buff" (Ridgway(1) color)), when bruised becoming mouse gray and then blackish; with entire edges, (Shaffer), more or less subdecurrent to decurrent when mature, sometimes separating from stem, at first attenuate-emarginate-attingent, close (8 gills per centimeter at 1 centimeter distance from margin on average), rather narrow (0.3-0.6cm broad), thin, often strongly forked, sometimes anastomosing; "white, sordid white, rarely with a slight orange-pallid tinge", "staining black where touched and often with black edge", (Singer)

Stem:
short; white, surface soon black from handling; unpolished, (Woo), 3-13cm x 2-5cm, stout, equal or narrowing downward, solid, rigid, very hard; white becoming grayish or brownish gray when old or where injured, then black; smooth, (Arora), 2.5-10cm x 2-8cm, equal or enlarging to the base or the top, straight or curved, round in cross-section or slightly flattened, solid becoming stuffed; white, when old or when bruised darkening like cap; bald to puberulent [finely hairy], unpolished, (Shaffer), 3-5.5cm x 1.5-3.5cm, central or somewhat eccentric, with various shapes, solid then stuffed, eventually hollow in many; "pure white, usually with the base browning, becoming black where scratched and later becoming blackish all over"; initially pubescent-pruinose, (Singer)

Odor:
indistinct (Woo), slight or none (Shaffer), fruity or none when young, eventually developing an "adusta odor" (of old wine barrels), (Singer)

Taste:
mild (Woo), mild or slowly peppery, (Arora), odd, mild with a menthol aftertaste, (Kibby), mild or faintly peppery (Shaffer), mild, slightly peppery after a few seconds, especially in gills, in very old specimens persistently mild and very slightly bitterish in the flesh, (Singer), mild, like menthol, (Miller)

Microscopic spores:
spores 7.7-10 x 6.7-8.2 microns, ornamentation Patterson-Woo type C-1, (Woo), spores 7-10 x 5.5-7.5 microns, elliptic to nearly round, with amyloid warts and ridges, (Arora), spores (6.9)7.7-10(10.6) x (5.9)6.7-8.2(9.5) microns, usually elliptic to broadly elliptic, occasionally oval, oboval, or nearly round, ornamentation usually 0.1 micron or less, the spores then appearing almost smooth, rarely up to 0.2 microns high, warts on a few spores are mostly isolated but "on most spores are mostly aligned or connected by fine lines, the whole then forming a broken to nearly complete reticulum"; basidia 43-70 x 7.3-11.4 microns, clavate, usually 4-spored, rarely 2-spored; pleuropseudocystidia abundant but sometimes inconspicuous, projecting not at all or moderately, arising in subhymenium or trama, 43-106 x 4-13.6 microns, subcylindric to fusoid, fusoid-clavate, or clavate, with apices rounded to acute or mucronate, sometimes capitate or with 2-few subapical constrictions, rarely branched, often curved basally, filled with refractive contents or partially empty, cheilopseudocystidia very common, 37-93 x 4-11.4 microns, of the same type as the pleuropseudocystidia or sometimes elongate-lanceolate with the long neck moniliform, blunt apically and devoid of contents (when present, the elongate-lanceolate type of cystidium also occurs on the lower gill faces, becoming shorter and grading into typical pleuropseudocystidia upward), cheiloleptocystidia rare to common, 16-36 x 3.3-8 microns, colorless, subcylindric to clavate or dumbbell-shaped, sometimes curved; cap cuticle "usually not embedded in gluten, rarely in an obscure layer of gluten which may be absent in places", "of interwoven, but generally horizontally oriented, non-gelatinous, septate, usually branched hyphae" mostly 1-6.7 microns wide, but at times up to 17 microns wide, "these hyphae sometimes with undulate outlines and occasionally ending in clavate cells or ascendant to erect undifferentiated hairs which may be clustered", with rare oleiferous hyphae 2-6.7 microns wide, (Shaffer), spores 7-8 x 7 microns, ornamentation IIIa-VII, (Singer), spores 8-9(11) x 6-7 microns, elliptic to ovoid-pyriform (oval-pear-shaped), warts usually less than 0.1 microns high, at times the wall smooth or nearly so, no fine lines observed; pleurocystidia 50-68 x 7-10 microns, "ventricose, clavate or cylindric, apices obtuse, appendiculate, at times moniliform, empty, granular, or banded", cheilocystidia 30-46 x 5-10 microns, "cylindric to ventricose or clavate, obtuse or subcapitate, empty", (Hesler)

Spore deposit:
white, Crawshay A, (Woo), white (Arora, Shaffer)

Notes:
Shaffer examined collections from WA, ID, CA, MI, NY, TN, VT, and France. C. Roberts (pers. comm.) found it on Vancouver Island in BC. There are collections at Oregon State University from OR.

EDIBILITY

said to be edible if thoroughly cooked, but a closely related Oriental species is poisonous, (Arora)

Synonyms and Alternate Names:
Russula sordida Peck
Russula subsordida Peck