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

Summary:
Subgenus Phlegmacium. Cortinarius porphyropus is one of the purple-staining Cortinarius purpurascens group. All parts of C. porphyropus fruitbodies stain purple when bruised or cut. Features include 1) a glutinous, grayish cap (that sometimes has a blue tinge) and becomes ochraceous brown to yellowish gray, 2) gills that are pale violaceous to grayish blue, then grayish brown, 3) a non-marginate club-shaped stem with at least the top pale violaceous when young, the stem grayish white with age, and 4) growth in hardwood and mixed forest with a particular preference for birch. Cortinarius cyanopus Fr. is regarded as a synonym in Hansen, L.(2), but is separately described by Kauffman(3) for Colorado.

Cortinarius porphyropus has been found at least in WA and has been reported from BC (J. Ammirati, pers. comm.), New England and NY northward (Phillips), and Europe.

Cap:
4-7cm across, (hemi-)spheric, then flat-convex; "(pale) grayish, sometimes with a bluish tinge", later more (pale) ochraceous brown to yellowish gray; "glutinous, slightly innately fibrillose or with hygrophanous spots or veins near margin", (Brandrud), 4-7cm across, light hazel, clay brown, yellow-brown, (Moser), 3-5(6)cm across, convex, then expanded-flat, margin inrolled at first; clay-tinged then "buffy-brown"; viscid, soon dry, innately virgate, (Kauffman), 3-7cm across, convex then flat; pallid ocher to buffy brown; sticky at first, (Phillips)

Flesh:
pale violaceous, more distinct in top of stem when young, turning lilac on bruising, (Brandrud), rather thin, soft; whitish but changing to "blackish-purple" when cut or bruised, (Kauffman), "pallid but bruising purplish" (Phillips)

Gills:
crowded; pale violaceous to grayish blue, then grayish brown, become distinctly lilac when bruised, (Brandrud), spotting purple where pressed, (Moser), "adnexed, then emarginate or subdecurrent by a tooth, close, moderately broad"; "vinaceous-purple" at first, at length "army-brown" or darker, changing quickly to "blackish-purple" when bruised; the edge entire, (Kauffman), "adnexed; purple bruising deeper purple", (Phillips)

Stem:
4-9cm x 1-1.5cm, club-shaped at base (to 2.5cm wide); at least top distinctly pale violaceous when young, grayish white when old, turning lilac on bruising, (Brandrud), club-shaped, silvery bluish violet, spotting purple where injured, (Moser), 4-7(8)cm x 0.5-1cm, equal or widening downward, fragile, spongy-stuffed; at first "vinaceous-purple" soon fading to pallid, but quickly blackish-purple when bruised; subglabrous [nearly bald] or fibrillose, (Kauffman), 4-9cm x 0.5-1.2cm, base swollen bulbous; violet at top, whitish elsewhere, bruising purple, (Phillips)

Veil:
sparse, fibrillose, violaceous-tinged, (Brandrud)

Odor:
distinct, honey-like when cut, (Brandrud), none (Kauffman), slight (Phillips)

Taste:
slight (Kauffman), mild (Phillips)

Microscopic spores:
spores 8-9.5 x 5-6 microns, elliptic, distinctly verrucose; gill edge more or less fertile, (Brandrud), spores 8.5-10.5 x 5-6 microns, (Moser), spores 9-12(13) x 5-6 microns, elliptic-oblong, smooth, pale brown under the microscope, (Kauffman), spores 9.3-10.9 x 5.3-6.3 microns, elliptic, warty, (Phillips), spores 8.6-11 x 5-6 microns, elliptic to slightly almond-shaped, moderately verrucose, yellow-brown; basidia 4-spored, 25-36 x 7-10 microns, narrowly clavate, with basal clamp connection; no pleurocystidia, marginal cells 15-18 x 6.5-8 microns, cylindric to clavate; cap cuticle of periclinal to somewhat ascending hyphae 2-5 microns wide, yellow-brown, uppermost layer gelatinized, some septa with clamp connections, (Breitenbach)

Spore deposit:
rusty brown (Phillips)