Summary:
Features include 1) an annual brown pore surface growing flat and firmly attached on conifer wood especially Douglas-fir, 2) when fresh with a narrow white, fringed margin, 3) soft flesh that is light in weight, and 4) microscopic characters including colorless oval spores, and conspicuous setal hyphae that project into the tubes. |What was thought to be a variation of Phellinidium weirii that affects Douglas-fir, true firs, and hemlock (as opposed to the one that affects Western Red-cedar and Alaskan Yellow-cedar) is now regarded as Phellinidium sulphurascens Pilat. Larsen et al. (1994) summarize the criteria for separating P. sulphurascens and P. weirii: 1) P. weirii usually occurs on Western Red-Cedar, whereas P. sulphurascens usually occurs on conifers other than Western Red-Cedar [such as Douglas-fir], 2) fruitbodies are usually perennial in P. weirii and usually annual in P. sulphurascens, 3) sporulation occurs in spring / mid-summer in P. weirii and in late summer / fall in P. sulphurascens, 4) in North America, pathogenesis by P. weirii does not result in death of the host - stem breakage is caused by butt-rot, but with P. sulphurascens in North America pathogenesis involved with root-rot results in death of the host and windthrow associated with "root-ball", 5) spores eventually have 2 germ tubes and germ tubes and juvenile mycelia are 2-3.5 microns wide in P. weirii, whereas spores have one germ tube and germ tubes and juvenile mycelia are 4.5-6 microns wide in P. sulphurascens, 6) dimensions of setal hyphae in wood and test tube culture are greater in P. sulphurascens, 7) columnar tufts of hyphae are present in test tube cultures at 6 weeks in P. weirii but not in at 6 weeks in P. sulphurascens, (Larsen, M.J.(11)). |The online Species Fungorum, accessed May 29, 2020, listed the current name as Coniferiporia sulphurascens, but MycoBank, accessed the same day, listed the current name as Phellinidium sulphurascens with Coniferiporia as an obligate or homotypic synonym.

Microscopic:
spores 4.5-6 x 3.5-4.5 microns, oval, smooth, inamyloid, colorless; basidia 4-spored, 10-11 x 5-5.5 microns, clavate, simple-septate at base; hymenial setae absent but projecting setal hyphae abundant, projecting up to 70 microns, 6-10 microns thick, straight, pointing toward the tube opening; hyphae of context of 2 other types: 1) 2.5-5.5 microns thick, "pale yellowish brown in KOH, thin-walled, with frequent branching, simple-septate", 2) 3-5.5 microns wide, "darker brown in KOH, thick-walled, with rare branching", (Gilbertson for P. weirii sensu lato), setal hyphae averaging 507.2 microns (with standard deviation 119 microns) x 6.2 microns (with standard deviation 1.3 microns), (Larsen, M.J.)

Notes:
Larsen, M.J.(11) used collections of P. sulphurascens from BC, WA, OR, ID, CO, and Russia and collections of P. weirii from British Columbia, Washington, Oregon, Idaho, and Alaska. P. sulphurascens occurs in southern BC, WA, OR, northern CA, western MT, northern ID, Russia, China, and Japan. P. weirii occurs in Washington, Oregon, Idaho, and Montana, (Gilbertson, including any P. sulphurascens collections).

Synonyms and Alternate Names:
Exidia spiculosa (Pers.) Sommerf.