Summary:
The Russula sororia group is typified by moderate size, a brown to grayish brown to dingy straw-colored cap, a tuberculate-striate cap margin when old, peppery tasting gills, and an unpleasant odor. There has been debate about which of the group occur in the Pacific Northwest, but R. cerolens is the common and only well documented member in that area. The rest of those tested are related to Russula recondita - these seem to be separable from R. cerolens by spore ornamentation, and perhaps lacking the central dark area of the cap. None of the collections from this whose DNA has been examined matched with R. sororia, R. pectinatoides, R. pectinata, or R. amoenolens. (D. Miller, pers. comm., using information that included Bazzicalupo(2)). |The group includes |1) R. cerolens, originally described from OR and CA and recorded from BC, with a dark brown cap with no grayish tints, peppery taste, pale yellow to yellow spore deposit, partially reticulate spores, (Thiers, whose description is used below), |2) (according to D. Miller, pers. comm., using information that includes Bazzicalupo(2)) three undescribed Pacific Northwest species closely related to Russula recondita Melera & Ostellari (described in 2016 from Europe) - these perhaps lack the dark central cap stain typical for R. cerolens and seem to be distinguishable from it by having mostly isolated warts on their spores (as opposed to having partially reticulate connecting ridges), but the three undescribed species are not easily distinguishable from each other, |3) R. sororia, according to Woo(1) by 1989 not yet reported from the Pacific Northwest, |4) R. pectinatoides, yellow-brown to sometimes gray brown cap, taste rarely peppery, cream to pale yellow spore deposit, non-reticulate spores, distinguished from R. cerolens according to Thiers by its pale to yellow brown cap and non-reticulate spores (Thiers), found in CA (Thiers) and included in Pacific Northwest key of Woo(1), but see the separate entry for detailed discussion of the name and its questionable presence in the Pacific Northwest, |5) R. pectinata (Bull.) Fr., yellow-brown to gray-brown cap, peppery taste, cream to pale yellow spore deposit, non-reticulate spores, see R. ''pectinata'' for further discussion of its characters and dubious presence in the Pacific Northwest, |6) R. amoenolens Romagn., gray-brown to occasionally dark yellow-brown cap, unpleasant weakly peppery taste, pale yellow spore deposit, non-reticulate spores, reported by Shaffer from IL, MA, and MI - Shaffer follows Romagnesi in stating that R. amoenolens is R. sororia in the sense of Schaeffer (1952) and R. pectinata in the sense of Singer (1958), and |Thiers gives three members of the group for CA: R. pectinatoides, R. cerolens Shaffer, and R. amoenolens Romagn. |R. amoenolens is described by Thiers as having 1) a cap that is dark brown to dark smoky brown to dark gray to dark olive-gray on the disc, fading to paler brown to somewhat yellow-brown toward the margin (and also as "smoky brown to gray-brown to olive-gray to occasionally dark yellow-brown" and as "brown to yellow-brown to ocher-brown"), 2) an odor that rather strong, unpleasant, often spermatic, 3) a taste that is unpleasant weakly peppery, often described as oily, 4) a pale yellow spore deposit, 5) spores with scattered warts and short ridges but not forming a reticulum, and 6) absent pileocystidia. |Thiers says R. cerolens Shaffer is very similar to R. amoenolens but has partially reticulate spores and a dark brown cap with no grayish tints. |According to Christine Roberts the member of this group found on Vancouver Island in BC is R. cerolens with "more reticulation on the warts". |The description of the R. sororia group is derived from Arora, and Thiers'' description of R. cerolens is given for further details. |The English name "comb Russula" is also used for R. pectinata.

Cap:
4-12cm across, convex becoming flat or shallowly depressed in center; "dark grayish-brown to hazel-brown when young, (rarely whitish), usually paler (yellow-brown to straw-colored or pale grayish-brown) toward margin or in age"; viscid when wet, bald, margin tuberculate-striate, (Arora), 5-10cm across, convex to nearly spherical when young, broadly and shallowly depressed when old, sometimes with an arched margin; dark yellow-brown to yellow-brown on disc, changing to brown to dark brown on older caps, sometimes the entire cap brown or near dark grayish brown on the disc and near olive-brown on the margin, unchanging in color when bruised; bald, viscid to subviscid when wet, moist to dry when older; margin downcurved, tuberculate-striate, striations 1.5-2.5cm long, cuticle hardly separable from flesh, (Thiers for R. cerolens)

Flesh:
brittle, firm; white, not bruising, (Arora), 0.2-0.3cm thick at disc; white, unchanging when exposed, both in cap and stem, (Thiers for R. cerolens)

Gills:
adnate to adnexed or free, close; whitish, sometimes with brownish or rusty stains when old, (Arora), "adnate then shallowly notched, close to subdistant, ventricose, not forking", not interveined, no subgills; "white when young, very pale yellow to pale olive tan" when old, usually with olive stains; "margin finely serrated or eroded", (Thiers for R. cerolens)

Stem:
3-8cm x 1-2.5cm, equal or narrowing downwards, often with 3 cavities within; whitish, often rusty-stained near base, (Arora), 3-4 x 1-1.5cm at top, equal to somewhat club-shaped, stem stuffed; white, developing reddish brown stains when bruised; dry, bald, (Thiers for R. cerolens)

Odor:
unpleasant (rancid or spermatic), (Arora), oily, unpleasant, spermatic, (Thiers for R. cerolens, but under R. pectinatoides he says the odor of R. cerolens is usually non-distinctive or faint), waxy when dried (Shaffer(8) for R. cerolens), strong, at first somewhat like bleach but with fresh, pleasant overtones, of ozone or cottonwoods in spring, eventually smelling strongly spermatic or of bleach, even after drying, (C. Roberts for R. cerolens sensu Shaffer 1972), Jerusalem artichokes, Camembert, spermatic, (C. Roberts for R. amoenolens sensu Romagnesi 1967), spermatic, like R. amoenolens but weaker, fruity, (C. Roberts for R. sororia sensu Romagnesi 1967), spermatic-waxy with fruity, fishy or rubber component, (C. Roberts for R. pectinatoides sensu Shaffer 1972), smoked herring, spermatic, camembert or pleasant, of Jerusalem artichokes when young, (C. Roberts for R. pectinata sensu Singer 1957)

Taste:
mild or slightly peppery, gills slowly but distinctly peppery (Arora), peppery (Thiers for R. cerolens), slowly peppery & soapy (C. Roberts for R. cerolens sensu Shaffer 1972), slowly acrid (C. Roberts for R. amoenolens sensu Romagnesi 1976), slowly strongly acrid, oily, (C. Roberts for R. sororia sensu Romagnesi 1976), spermatic, waxy, mildish to faintly acrid, (C. Roberts for R. pectinatoides sensu Shaffer 1972), acrid, sometimes slowly, (C. Roberts for R. pectinata sensu Singer 1957)

Microscopic spores:
spores 6-9 x 5-7 microns, broadly elliptic with amyloid warts, (Arora), R. sororia, R. amoenolens, R. pectinatoides, and R. pectinata have isolated or fairly isolated warts, while R. cerolens has more reticulation on the warts, (Christine Roberts, pers. comm.); spores 6-8.5 x 5-6.9 microns, "mostly subovoid to subglobose", "ornamentation composed of scattered heavy warts and short heavy ridges sometimes forming an obscure partial reticulum", warts 0.4-0.6 microns high; hymenial cystidia scattered to common, projecting from hymenium, 50-70 x 9-13 microns, clavate with narrow, elongated, strangulated terminal appendage, colorless in KOH, very thin-walled, (Thiers for R. cerolens; he gives the spores for R. amoenolens as 5.5-10 x 4.5-7 microns, "ornamentation composed of scattered, obtuse warts and short heavy ridges, not forming a reticulum", but confuses the issue by characterizing it as having reticulate spores; Thiers gives the spores for R. pectinatoides as 6.5-8.5 x 5.5-7 microns, "ornamentation composed mostly of scattered, moderately heavy warts or spines with few or no heavy ridges and rare to scattered connectives, not forming a reticulum or forming an obscure one")

Spore deposit:
creamy to pale yellow (Arora), pale yellow to yellow (Thiers for R. cerolens)

Notes:
Members of the group have been found in the Pacific Northwest at least in BC, WA, and OR. Most of them fit Russula cerolens.

EDIBILITY

might be poisonous (Arora)