Summary:
Asterophora parasitica is characterized by small size, growth on Russula and Lactarius mushrooms, non-powdery, dirty white silky cap, and well-formed to distorted gills with chlamydospores.

Cap:
0.8-2(3)cm across, hemispheric or obtusely conic expanding to flat-convex or flat - bell-shaped with wavy to cleft, downcurved to uplifted margin; white to pale gray when young, becoming gray-brown from margin inward when old; dry, dull, silky-fibrillose, (Castellano), 0.5-3cm across, convex, then conic - bell-shaped to flat or slightly concave, may be umbonate; finely whitish fibrillose or appressed silky floccose, becoming fuscous or grayish tinged rufescent, (Corner), white to pale gray, becoming grayish brown when old, (Bessette), white to grayish, brownish, or lilac-tinged, (Arora), smooth or radially striate to silky, (Courtecuisse), "whitish, brownish, grayish or faintly lilac" (Trudell)

Flesh:
thin; whitish to brownish, (Bessette)

Gills:
broadly adnate to subdecurrent [somewhat decurrent], distant, ventricose, broad (0.1-0.2cm), thick, sometimes interveined when old; white to pale gray-brown or brown, (Castellano), adnate to decurrent, rather distant, becoming thick and fleshy at base, minutely floccose but waxy-smooth near margin, blunt, entire, becoming distorted and anastomosing, 16-27 primaries 0.1-0.2cm wide, 2-3 ranks; white, then fuscous or fuliginous, (Corner), attached to subdecurrent, often poorly developed, occasionally forked; whitish to grayish brown; edges typically finely granular (Bessette), well-formed, distant; gray, (Courtecuisse)

Stem:
1-3cm x 0.2-0.3cm, central, round in cross-section, equal, stuffed to solid; white over pale gray-brown background; dry, dull, silky fibrillose with tomentose base, (Castellano), 1-6cm x 0.08-0.4cm, very variable in length, nearly cylindric or widening slightly downwards, often curved, fibrous, becoming hollow; white; cottony pubescent or subtomentose especially towards base (Corner), fine white fibers on grayish brown ground color, base sometimes minutely velvety and white, (Bessette)

Odor:
unpleasant, farinaceous, (Castellano), strong, sour, like Polyporus squamosus, (Corner), unpleasant (Bessette), very strongly mealy (Courtecuisse)

Taste:
unpleasant, farinaceous, (Castellano), typically farinaceous (Bessette)

Microscopic spores:
spores 5-7 x 3-4 microns, elliptic, smooth, inamyloid, cyanophilic, thin-walled; chlamydospores on gill edges and faces when mature, 12-17 x 9-11 microns, fusoid, smooth, colorless to pale yellow-white; cap cuticle "a cutis of repent radially arranged hyphae" 4-15 microns wide, cylindric or with clavate terminal cells, colorless, inamyloid; clamp connections present, (Castellano), spores 5-6(7) x 3-4 microns, (Corner), spores 5-6 x 3-4 microns, elliptic, smooth; gills also produce spindle-shaped to oval chlamydospores 12-17 x 9-10 microns, typically thick-walled, colorless, inamyloid, (Bessette), basidiospores 5-6 x 3-4 microns, elliptic, smooth, colorless, generally lacking; chlamydospores in the gills, 12-17 x 9-10 microns, fusiform, smooth, colorless, with large droplets; basidia siderophilous according to literature, but not found by these authors; cystidia not seen; cap cuticle of parallel hyphae 4-14 microns wide, occasional hyphae ends exserted, septa with clamp connections, (Breitenbach), chlamydospores elliptic (Trudell)

Spore deposit:
white (Bessette)

Notes:
It has been found at least in OR and CA, and has been reported from BC by Christine Roberts (pers. comm.), and from WA by M. Beug (pers. comm.). Breitenbach(3) give the distribution as North America, Europe, Asia, and North Africa.

EDIBILITY

unknown (Bessette)

Synonyms and Alternate Names:
Nyctalis parasitica Fr.