Microscopic:
spores (55)60-90(100) x 4-5 microns, subcylindric [nearly cylindric], slightly narrowing toward one or both ends, straight to slightly curved, brown, 0-7-septate, many collections mostly 3-septate, others mostly 7-septate; asci 8-spored, 175-250 x 12-14 microns, clavate; paraphyses straight to somewhat curved in upper part, narrowly cylindric in lower part, sparsely septate, with the terminal cells pyriform [pear-shaped], broadly obovoid or nearly spherical, continuing down the stem in a thick gelatinous layer; colorless in lower part, light to dark brown in upper part or entirely dark brown, (Mains), spores 55-102 x 5-6 microns, multiseriate in ascus, cylindric, or slightly narrowed toward the rounded ends, fuliginous, at first simple, then 3-septate, finally in most cases 7-septate; asci 8-spored, reaching a length of 250 microns and a width of 12-15 microns, narrowly clavate, narrowed from middle toward apex, the pore blue with iodine; paraphyses 3 microns thick, cylindric, septate, longer than asci, the apices pale brown and abruptly pyriform to globose thickened, 8-10 microns thick, (Seaver), 60-90 x 4-5 microns, smooth, brown, with 0-7 (usually 3 or 7) septa, (Arora)

Synonyms and Alternate Names:
Oligoporus balsameus (Peck) Gilb. & Ryvarden
Polyporus balsameus Peck