Summary:
{See also Earthstars Table.} The most important field characters are the asperulate surface of the spore sac and the sulcate [pleated] peristome, (Smith(49)). There are 6-12 rays which are hygroscopic.

Microscopic:
spores (4.5)4.8-5.7 microns in diameter excluding ornamentation, 5.6-6.7 microns in diameter including ornamentation, "verruculae isolated, irregular in outline", 0.3-0.6 microns high, 0.3-1.2 microns wide, "This species seems to vary noticeably with regard to size and colour of the mature spores, and coarseness of the warts."; basidia not seen, capillitial hyphae pale yellow to almost colorless, "finely tapered, occasionally forked or lobed, thick-walled with a narrow lumen, smooth or partially encrusted", (Pegler), spores 6-7.5 microns in diameter, round, very dark brown in KOH, coarsely asperulate with colorless plugs "extending into a gelatinous matrix", "apedicellate or pedicel present only as a broken stump"; capillitial threads 3-5 microns wide, slightly flexuous, pale yellowish in KOH, walls thickened, no cross walls seen, rarely branched, (Smith(49))

Notes:
A collection from BC was deposited at the University of British Columbia and determined by Paul Kroeger. It is widely distributed through northern temperate regions (Pegler(4)).

Synonyms and Alternate Names:
Phellinus viticola (Schwein.: Fr.) Donk
Polyporus viticola Schwein.: Fr.