Summary:
Also listed in Toothed category. Features include a white to cream pore surface that becomes strongly tooth-like, and may bend outward to form white hairy caps, growth on hardwood, and microscopic characters including conspicuously incrusted cystidia and an absence of clamp connections. The description is derived from Gilbertson(1) except where otherwise noted. It is common in North America except in the southwest (Gilbertson).

Microscopic:
spores 5-7 x 2-3 microns, oblong to cylindric, straight to slightly curved, smooth, inamyloid, colorless; basidia 4-spored, 20-25 x 4-6 microns, clavate, developing in intricate branched candelabra, simple-septate at base; cystidia conspicuous and abundant, "50-110 x 5-10 microns, projecting up to 40 microns, originating in the subhymenium from tramal skeletal hyphae", thick-walled, heavily incrusted apically, illustrated as cylindric; hyphal system dimitic: context generative hyphae 2-4 microns wide, thin-walled to firm-walled, with frequent branching, simple-septate, context skeletal hyphae 2.5-6 microns wide, colorless, "thick-walled, occasionally simple-septate, with rare branching", trama hyphae similar

Spore Deposit:
white (Lincoff)

Notes:
Irpex lacteus has been found in BC, WA, OR, ID, AB, MB, NWT, ON, PQ, AL, AR, CT, DE, FL, GA, IA, IL, IN, KS, KY, LA, MA, ME, MN, MO, MT, NC, ND, NE, NH, NJ, NM, NY, OH, PA, SC, SD, TN, VA, VT, WI, WV, and WY, (Gilbertson).

Synonyms and Alternate Names:
Peniophora hydnoides Cooke & Massee
Phlebia hydnoides (Cooke & Massee) M.P. Christ.
Plicaria fulva R. Schneider