Summary:
The features of Tetrapyrgos subdendrophora include 1) small size, 2) a circular to ear-shaped, convex, white, hoary cap that stains bluish gray to grayish brown when old, 3) distant, white, anastomosing pseudogills, 4) short, lateral, minutely hoary, whitish to blackish stem, 5) growth on grasses, sedges, and berry canes, and 6) microscopic characters including pyramidal to tetrahedron-like spores. It is rarely collected.

Cap:
0.5-1.16cm, circular to ear-shaped, convex; white, color not changing but herbarium specimens yellow-brown with age; dry, somewhat translucent, minutely canescent [hoary]

Gills:
pseudogills, anastomosing, up to 0.2cm distant; white, (Redhead(10)), "shallowly adnexed to adnate", distant with 1-2 tiers of subgills, anastomosing and interveined when old; "white, staining bluish gray", (Desjardin), "shallowly adnate to adnexed, distant", with 1-2 series of subgills, "strongly anastomosing and intervenose, edges pruinose, white, staining the color of the cap when old", (Honan)

Stem:
short, lateral, minutely canescent, gray, (Redhead(10)), 0.1-0.3cm x 0.05cm, "eccentric to nearly lateral, curved, arising through a cleft" in the cap, cylindric or narrowing downwards, "tough, solid, insititious"; "apex white, base bluish black to black" [photographs show stem predominantly blackish]; "dry, white-pruinose overall", (Desjardin), 0.05-0.3cm x 0.05-0.1cm, "eccentric to strongly eccentric, appearing lateral in side view", arising through the cleft in cap, "even or slightly tapered downward, solid"; white at apex, "base black to blue black"; "white-pruinose overall, arising from a black basal disc", (Honan)

Odor:
none noticed, (Redhead(10)), indistinct (Desjardin), not distinctive (Honan)

Taste:
indistinct (Desjardin), not distinctive (Honan)

Microscopic spores:
spores 8-10 x 6-7 microns, triangular, pyramidal, or tetrahedron-like in shape, inamyloid, colorless, sometimes guttulate; basidia 4-spored, 28-35 x 7-8 microns, clavate; tibiiform cystidia abundant on pseudogills and cap margin, occasionally intermixed with dendrophysoid elements forming a "Rameales" structure on the cap; metuloids lacking; trama and context hyphae with clamp connections, gelatinized, 1.5-2 microns wide, (Redhead(10)), spores 8-12 x 5.5-10 microns, "triangular to tetrahedral", inamyloid, colorless; cheilocystidia, pileocystidia and caulocystidia cylindric-capitate, "densely diverticulate", clamp connections present [at least in cap cuticle], (Desjardin), spores (6.4)8-12 x (4.8)5.6-10.4 microns, "triangular to shallowly tetrahedral, often with a large vacuole", colorless, "inamyloid, thin-walled"; basidia 4-spored 36-45 x 3.2-8 microns, clavate, colorless, "inamyloid, thin-walled, clamped"; basidioles 28-38 x 4-7 microns, "clavate to fusoid", colorless, "inamyloid, thin-walled"; pleurocystidia and cheilocystidia common, 40-64 x 3.2-9.5 microns, irregularly cylindric, apex capitate 6.5-9.5 microns in diameter, colorless, "inamyloid, thin-walled to firm-walled" (up to 0.7 microns thick), "ranging from non-diverticulate to somewhat densely diverticulate on the central axis, pedicellate, rarely entirely diverticulate", diverticula 0.8-4(8.8) x 0.8-2.4(4.8) microns, cylindric or knob-like, "occasionally branched"; cap cuticle a Rameales-structure "of loosely interwoven diverticulate hyphae with suberect to erect terminal cells", terminal cells 35-53 x 3-8 microns, irregularly cylindric, "densely diverticulate below a clavate to bulbous capitulum", 5.5-8 microns in diameter, "apex occasionally thick-walled", colorless, "inamyloid, thin-walled", diverticula 0.8-4 x 0.8-3.2 microns, cylindric to knob-like, occasionally conic or branched; stem cuticle similar to cap cuticle; clamp connections present, (Honan)

Spore deposit:
white (Desjardin)

Notes:
It is found at least in BC (including the holotype) and OR, (Redhead). T. subdendrophora is also found in CA (Desjardin).

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Synonyms and Alternate Names:
Campanella subdendrophora Redhead