Crust white, becoming brown, not separating, growing in temperate regions.
Spores smooth, 8-9 X 5
“it is near Polyporus applanatus in form, consistency and volume, but differs essentially in the color of the cap and the pores and especially in the presence of a wide sterile border circumscribing the tubes below.” http://archive.org/stream/jstor-2478555/2478555_djvu.txt
Elfvingia megaloma (Lév.) Murrill, Bull. Torrey
Club 30: 300. 1903.
Pileus hard, woody, dimidiate, applanate, 6—15 X 8-30 X 1—4 cm.; surface milk-white to gray or umbrinous, glabrous, concentrically sulcate, encrusted, fasciate with obscure lines, conidia-bearing, usually brownish during the growing season from the covering of conidia; margin obtuse, broadly sterile, white or slightly cremeous, entire to undulate: context corky, usually rather hard, zonate, fulvous to bay, 5—10 mm. thick, thinner with age; tubes very evenly stratified, separated by thin layers of context, 5—10 mm. long each season, avellaneous to umbrinous within, mouths circular, 5 to a mm., whitish-stuffed when young, edges obtuse, entire, white or slightly yellowish to umbrinous, quickly changing color when bruised: spores ovoid, smooth or very slightly roughened, pale yellowish-brown, truncate at the base, 7-8 X 5-6 um.
TYPE LOCALITY : New York.
HABITAT: Abundant on dead or diseased trunks or timber of most deciduous trees; also on conifers in certain sections.
DISTRIBUTION : Canada to the mountains of Alabama and west to California.
Exsiccati: Thum. Myc. Univ. I804 ; Rab.-Wint. Fungi Eur. 3736; Ellis, N. Am. Fungi 801 : Shear, N. Y. Fungi 34. https://books.google.com/...