Pileus dimidiate, imbricate, often narrowly attached, with a prominent umbo, variable in habit and size, soft, spongy when fresh, fragile when dry, 1-2 X 3-6 X 0.5-1.5 em.; surface sod- den, tomentose or villose-tomentose, azonate, murinous or griseous when fresh, becoming caesious or fading to nearly pure- white on drying, often nearly glabrous with age; context white, soft, friable, 5-8 mm. thick; tubes long and slender, 5-10 mm. long, caesious within, collapsing, friable, mouths angular, 3-4 to a mm., edges white or bluish-gray, very thin, dentate to long and sharply lacerate; spores elongate, 5-5.5 X 1.5 p..
Occasional in VVashington and Oregon on dead coniferous wood. It occurs also on deciduous wood.
These notes come from Cyanosporus caesius (Schrad.) McGinty when it was merged with this name:Nomenclature: [#144401]: IF, MB
Per Shen, et al., Persoonia 42, 2019: 101–126. https://doi.org/10.3767/persoonia.2019.42.05:
… Cyanoporus is supported as an independent genus which contains the Postia caesia complex and seven other clearly distinguished new species from China. Phylogenetically, the new species are closely related to the Postia caesia complex; all the species in the complex form a well-supported lineage (Fig. 1, 2), which is distant from Postia s.str. Morphologically, Cyanoporus differs from Postia s.str. by its more or less bluish basidiocarps, usually narrow allantoid, thin- to slightly thickwalled and weakly cyanophilous basidiospores.