E-Flora BC: Electronic Atlas of the Flora of British Columbia

Summary:
Clade Russula crown. Features include 1) a viscid cap of variable color but typically purplish with a greenish yellow center (but it may be many shades of purplish, olive-green, and brown, usually in mixtures of them), 2) flesh that turns gray or black, often with an intervening reddish phase, when cut or bruised, 3) subcrowded, pale yellow gills that often darken at the edges when bruised, 4) a white stem that becomes grayish or sordid, 5) a mild odor and taste, 6) a cream spore deposit, and 7) a magenta reaction of the stem to PDAB. |The variability of Russula ''cyanoxantha'' is a source of confusion with R. occidentalis. |Russula occidentalis Singer is given as a synonym, along with R. occidentalis Bon, of Russula viscida Kudrna in Species Fungorum, accessed January 13, 2019 and April 4, 2020, but Bazzicalupo(2) regarded R. occidentalis as R. vinosa. It has been regarded in the past as a variety of R. vinosa, but two collections identified as R. vinosa matched DNA from Ben Woo''s collections, implying that the separation as a variety was unwarranted.

Singer examined collections from WA, OR, and ID. It is included by Thiers(3) for CA. C. Roberts (pers. comm.) reported it from Vancouver Island in BC. Collections from BC are deposited at the Pacific Forestry Centre and the University of British Columbia.

Cap:
6-13cm across, "usually purplish with yellow-green center, but also with extremely variable colors, sometimes completely purplish, or olive-green with brownish lavender margin, or yellowish-brown shading to rosy purple margin", sometimes with bluish green shades at center and bluish purple at rim, sometimes found especially in young specimens with a definite blue cast; drying dull or with slight sheen, cap skin separable, margin usually even or very slightly striate, (Woo), 5-15cm across, convex with broadly depressed center, more flat when quite old; "Prussian red" to "hematite red", "deep purplish vinaceous", mixed greenish or olive tints ("veviter green", later "tea green") or buff ("cream buff" on disc and "dark olive buff" on margin), the margin rarely "light cinnamon drab" when old with the disc becoming "olive buff", all these colors occurring in various combinations, but the margin most frequently remaining "dull lavender", the center often almost black; bald to subpruinose-subpubescent and opaque when dry, but apparently bald and viscid when wet (although drying very rapidly), becoming more bald on the center than on the margin, with cap skin separable from halfway to completely, "with smooth or short tuberculate-sulcate margin", (Singer), 6-13cm across, "usually purplish with yellow-green center but very variable in color, sometimes with bluish green shades at center and bluish purple at margin"; viscid when wet, cuticle peels halfway, (Phillips), 5-13cm across, flat to broadly rounded with depressed center; "color variable, usually light purplish with a pale yellow or olive greenish center sometimes grayish red centrally, the various colors sometimes mixed with brown or more purplish overall"; viscid drying dull or somewhat shiny, slightly striate on margin, (Ammirati), variable in color, "usually it is purplish with a yellow-green center, but it can appear in many shades of purplish, olive-green, and browns, usually in mixtures", (Trudell(4))

Flesh:
fairly firm; white, turning slowly reddish when cut, eventually grayish to gray black, (Woo), rather firm at first, but fragile when old; white unchanging in young material if not quite fresh, otherwise usually changing when bruised, scratched, or cut, at first to reddish, or directly (and then more slowly) to cinereous or gray, the reddening more localized in the stem, (Singer), "firm; white, turning slowly reddish when cut, then gray to black", (Phillips), soft; white bruising reddish then gray to black, (Ammirati)

Gills:
subcrowded; pale yellow, blackening at margin when old, (Woo), narrowed to the stem, crowded to subdistant, equal, anastomosing, occasionally forking, especially in inner third, narrow, up to 0.6cm broad, to broad, 1-1.5cm broad, broadest in marginal third, rather thick; white, then pale cream, dirty cream when old, the edges either unchanging or becoming sordid brownish when bruised or graying, (Singer), subcrowded; pale yellow, blackening at margin when old, (Phillips); touching the stem, close together or slightly spaced when old; pale yellow, edges often blackening when old, (Ammirati)

Stem:
white, often ashy when old, bruising first reddish then gray, (Woo), 5-10cm x 1.5-3cm, equal or near so, sometimes narrowing and curved at the base, rarely swollen-ventricose; spongy-firm but becoming hollow when old; white, the base at times with sordid yellowish blotches, "usually becoming slowly cinereous or sordid", usually strictly unpolished, sometimes initially exuding watery drops, then slightly subpruinose to subvelutinous but becoming bald, sometimes longitudinally short-rugose at top, otherwise smooth to subrugulose, (Singer), 5-8cm x 1.5-2.5cm, firm; white, often grayish when old, bruising reddish then brown, (Phillips), up to 5cm long, soft and spongy within; white bruising reddish then dark gray to black, (Ammirati)

Odor:
none to faintly fruity (Woo), weak (Singer), none (Phillips)

Taste:
mild (Woo, Singer, Phillips)

Microscopic spores:
spores 8-10 x 7.5-9 microns, Patterson-Woo type A-3, B-3, (Woo), 9-14 x 8.5-12 microns, ornamentation (1)1.5(2) microns high, the general impression always that of isolated echination [spines]; basidia 4-spored, 50-55 x 14.2 microns; pleuropseudocystidia and cheilopseudocystidia 80 x 10-10.8 microns, "with banded contents, more often acute than obtuse"; epicutis of cap formed by hyphae that are equal, smooth, "empty", clampless, 1-3.5 microns wide, "filamentous, and making up a trichodermium which becomes depressed in an early stage"; "hyphae of hypodermium similar but more repent and pigmented", (Singer), spores 8.5-11.4 x 6.5-7.7 microns; cap cuticle up to 150 microns thick, epicutis "a layer of loosely interwoven hyphae with free hyphal tips and few poorly differentiated pileocystidia", the latter absent in some fruitbodies, (Thiers), 8-10 x 7.5-9 microns, nearly round to elliptic, ornamentation large protuberances, some connected by lines, (Phillips)

Spore deposit:
cream, Crawshay B, (Woo), varying from intensity of D and tone quality of between C and E to between E and F (nearer to E), (Singer), cream, Crawshay B, (Phillips)