Summary:
Features include 1) large size, 2) a dry, bald, white or pallid cap, the cap margin tomentose at first, 3) adnate or somewhat sinuate, broad gills that are white or pallid, 4) a white stem, at times with a marginate bulb, 5) a mild odor and taste, 6) grassland habitat, 7) a pinkish buff to pale pinkish cinnamon spore deposit, and 8) microscopic characters including inamyloid, elliptic spores that are finely warty to smooth.

Cap:
(5)10-30cm across, convex becoming flat, margin incurved at first; white or pallid, becoming creamy to light brown when old; dry, bald, dull, smooth at first then fissured to areolate [cracked like dried mud] or warty when old, margin tomentose at first, not striate

Flesh:
thick on disc, firm; white

Gills:
adnate or somewhat sinuate, becoming rounded and seceding when old, close to subdistant, broad (up to 1.2cm broad); ''whitish or pallid (with a pearly sheen)''

Stem:
3-7cm x 1.5-5cm, nearly equal or base enlarged, at times with a marginate bulb, solid; white, base may be spotted brown; bald or fibrillose

Veil:
[none]

Odor:
not distinctive

Taste:
not distinctive

Microscopic spores:
spores (5.5) 6-8 x (3.5)4-4.5(5.5) microns, elliptic, mostly verruculose [finely warty] but sometimes smooth, inamyloid, walls and ornamentation usually cyanophilic; basidia usually 4-spored, rarely 2-spored, 23-37 x 5.5-8.5 microns; [presumably without pleurocystidia or cheilocystidia]; clamp connections present

Spore deposit:
"pinkish-buff" to "pale pinkish cinnamon"

Notes:
Material was examined from ID, AB, SK, CO, and WY, (Bigelow(5)). There are collections from BC at the University of British Columbia and collections from WA at the University of Washington.

EDIBILITY

Synonyms and Alternate Names:
Clitocybe praemagna (Murrill) H.E. Bigelow & A.H. Sm.
Melanoleuca praemagna Murrill
Tricholoma praemagna (Murrill) Murrill