Summary:
Subgenus Phlegmacium. Distinctive features are the even, dark violet-blue colors of all parts and the change of all parts to purplish lilac when bruised. |Cortinarius occidentalis is a member of the purple-staining Cortinarius purpurascens group, but it is also a group of several species in its own right. |The molecular study of Liimatainen(2) found Cortinarius mutabilis A.H. Sm. to be identical to Cortinarius occidentalis A.H. Sm. and they consider the latter to be the correct name for the type of Cortinarius mutabilis A.H. Sm. Cortinarius ''mutabilis'' has been commonly identified in the Pacific Northwest, and its description is also retained at present for comparison under that name. Smith(12) also first considered Cortinarius mutabilis first to be a form of Cortinarius occidentalis A.H. Sm. and his tentative differentiation on the basis of developmental stages could be set aside in light of the molecular evidence. |The description is derived from Smith(22).

Gills:
adnate, seceding readily, broad, moderately close; colored as young caps, changing to "purplish lilac" when bruised, tawny brown at maturity

Stem:
5-7cm x 1-1.6cm, equal above a flaring marginate bulb which tends to disappear when old, solid; colored as cap, changing to "purplish lilac" when bruised; faintly fibrillose from veil remnants

Microscopic spores:
spores 7-9(10) x 5-5.5 microns, oval, slightly roughened, pale rusty under microscope

Spore deposit:
[presumably a shade of brown]

Notes:
Cortinarius occidentalis was found by A.H. Smith in WA in 1935 and CA in 1937. With the synonymy of C. mutabilis, OR and BC are added to the distribution.

EDIBILITY