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Species Information
Summary: {See also Blackening Russulas Table.} Clade Compacta. In preliminary unpublished research, the Pacific Northwest has 3 genetic species close to R. adusta (one may be the real R. adusta), (D. Miller, pers. comm.). Russula adusta group is characterized by 1) a fruiting body that becomes smoky brown or black when cut or bruised, sometimes with an intermediate reddening phase, 2) a sepia to gray brown cap with an inseparable cap skin, 3) hard, compact flesh, 4) close gills, 5) sometimes an odor of wine barrels, 6) a mild taste, and 7) a white spore deposit. This species has erratic staining reactions: the flesh normally bruises smoky-brown or grayish-black, but may show a slight reddish intermediate phase.
It has been found at least in WA, ID, ON, ME, and France. Thiers lists it for CA (rare). It occurs on Vancouver Island in BC (Roberts, C.(2)).
Cap: 7-12cm across, "white to pallid buff when young, becoming grayish brown or lead gray or blackish"; "viscid drying shiny, margin even, cap skin inseparable", (Woo), 5-12cm across, "when young convex with incurved margin and slightly depressed disc", expanding to convex and then flat with depressed disc, the margin becoming raised when old; whitish to sordid light buff becoming "grayish brown, sepia, or blackish"; viscid, bald, shining, "with cuticle scarcely separable and margin not striate", (Shaffer); 5-15cm across, flat then depressed at center, margin strongly inrolled; white to pale buff; viscid when wet, (Phillips)
Flesh: hard, brittle; whitish slowly turning black when cut, "sometimes showing a slight reddening phase", (Woo), firm, brittle; whitish, slowly blackening when bruised or when old, "sometimes showing an indistinct reddish tinge when bruised", (Shaffer), "white, slowly pinkish when cut, then brown", (Phillips), R. adusta "blackens only slightly, and the flesh pinkens lightly when cut", (Trudell)
Gills: close but not crowded, regular subgills; whitish, turning black when old, (Woo), adnate, close, with subgills, moderately broad (0.4-1cm broad), intervenose, occasionally forked; when young whitish, becoming dingy pale yellow to pale vinaceous buff, when bruised or when old becoming blackish, (Shaffer), "subdecurrent, very crowded, narrow; white to cream", (Phillips)
Stem: short, stout", "white bruising black, (Woo), 3-6cm x 1.5-2.5cm, equal or narrowing toward base, solid; whitish, slowly blackening when bruised or when old; bald to puberulent [with fine hairs], (Shaffer); 4-10cm x 2-4cm, "hard; white bruising reddish brown", (Phillips)
Odor: "with odor of empty wine casks (according to European authors) or not distinctive" (Shaffer), of sour wine, (Phillips), not of empty wine casks for Vancouver Island collections, but sometimes smell a bit like bread, (Roberts, C.), odor of empty wine barrels has not been noticed in Pacific Northwest specimens (Trudell)
Taste: mild (Shaffer), sweet (Lincoff), mild (Phillips), a bit like bread (Roberts, C.)
Microscopic spores: spores 7-9 x 6-8 microns, ornamentation Patterson-Woo type D-1, (Woo), spores 6.8-9.4 x 5.6-7.7 microns, usually broadly elliptic, nearly round (nearly round) or oboval, occasionally elliptic, ornamentation 0.1-0.4 microns high, "a nearly complete to complete reticulum of warts connected by fine to moderately heavy lines, at times the warts not distinct on the reticulum, occasionally with a few isolated warts"; basidia 4-spored, 40-65 x 8.6-10.6 microns, clavate; pleuropseudocystidia abundant, 47-122 x 4-7.3 microns, "subcylindric to fusoid or clavate", with apices rounded or acute, "sometimes capitate, bearing a finger-like projection, or with 2-3 subapical constrictions", sometimes curved basally, "filled with refractive contents to almost empty", arising in subhymenium or trama, projecting not at all to prominently (0-36 microns beyond basidiole tips), cheilopseudocystidia rare to fairly common, 27-53 x 3.3-6.7 microns, of same type as pleuropseudocystidia, cheiloleptocystidia 15-36 x 4-6.7 microns, oval, subcylindric, clavate or fusoid, "with apices usually rounded, sometimes capitate", colorless, abundant, (Shaffer); spores 7-9 x 6-8 microns, broadly elliptic, warts small under 0.5 microns high, ridges fine, abundant, well developed reticulum, (Phillips)
Spore deposit: white, Crawshay A (Woo), white (Shaffer, Phillips)
Habitat / Range
conifers (Woo), usually under conifers (Phillips), late summer to fall (Buczacki)
Similar Species
The blackening Russulas, Russula dissimulans, Russula nigricans, Russula albonigra, and Russula atrata have dry or dry to subviscid caps. |Russula densifolia is the most similar and is difficult to distinguish: R. adusta has a sepia to grayish brown cap as opposed to yellow-brown for R. densifolia, odor mild or of empty wine casks as opposed to earthy, taste mild instead of mild to peppery (always peppery in gills), less pronounced reddening of flesh when cut or bruised (before blackening), and close but not crowded gills as opposed to crowded gills, (Woo). Lange says in Flora Agaricina Danica (1940), with Latin names in italics, ''It is rather questionable whether no. 2 and no. 3 can be clearly distinguished. Typical specimens of R. densifolia are more brown, those of R. adusta are more dull gray, but intermediate colors occur. And in most cases a slight rubescence takes place (but very slowly), even in "typical" specimens of R. adusta, while they are in bud'', (Lange(1)). Shaffer gives a table that includes the following differential points: gills crowded for R. densifolia, close for R. adusta, taste acrid for R. densifolia, mild for R. adusta, odor not distinctive for R. densifolia, of empty wine casks for R. adusta, color change through reddish to blackish for R. densifolia, directly to blackish for R. adusta. |Roberts says of Vancouver Island specimens, "The identification of these collections as Russula adusta rather than R. densifolia was made on the basis of a mild taste, the lack of a distinct red phase in the bruising reaction, which was at most a pinkish-brown, their similarities to a European collection of R. adusta and the difference between these collections and that of a Russula densifolia from Oregon. Although the spores are very close in size and description between the two species, the Vancouver Island collections had spores with a slightly lower ornamentation than that of the Oregon R. densifolia, in keeping with the observations of Shaffer (1962), Sarnari, (1998) and Romagnesi (1967). The spores however still have slightly coarser and higher ornamentation than in those authors'' descriptions, and are more like the drawings and descriptions of spores of R. adusta by Thiers (1997) of California material. The European collection of R. adusta had a weak but definite odour of wine corks and a very slow bruising reaction, the flesh only becoming dingy grey a day after cutting. Pacific Northwest collections of R. adusta do not seem to have this wine cork odour, but they taste and sometimes smell a bit like bread, another fermentation product of yeast. There are some anomalies with the Vancouver Island collections - R. adusta should have a brownish pink reaction with FeSO4 rather than the greenish grey that is typical for R. densifolia (sensu Shaffer 1962, but not Singer, 1957). Both Shaffer (1962) and Thiers (1997) comment on the occurrence of collections that appear to intergrade between R. densifolia and R. adusta, in taste, spores and bruising reactions, so the differentiation between these species can be difficult.". |See also SIMILAR section of Russula occidentalis.
