Summary:
{See also Stereum Table.} Features include 1) growth on hardwoods, 2) a leathery fruitbody bent outward to form a shelf-like cap, or fan-shaped, (in both cases strongly radially pleated), 3) cespitose or strongly confluent habit, often shingled, 4) a cap surface that is shiny-silky, scantily tomentose to bald, with alternating concentric zones of orange and brownish that fade, 5) a spore-bearing surface that is smooth or slightly ridged, colored orange fading to cream buff to cinnamon buff, and sometimes bruises red, 6) spores that are cylindric (often slightly curved), smooth, and colorless, and 7) conducting hyphae and sharp-tipped hyphidia. |Stereum complicatum is the most common North American species of Stereum, according to Lincoff(2). |Stereum complicatum, Stereum gausapatum, Stereum hirsutum, and Stereum ochraceoflavum are members of the subgenus Stereum, having sharp tipped hyphidia but lacking the pseudoacanthohyphidia found in subgenus Aculeatostereum. |Stereum complicatum is also a member of the Stereum hirsutum complex which according to Welden in 1971 (referred to in Chamuris(4)) includes 1) Stereum hirsutum, 2) Stereum complicatum, 3) Stereum gausapatum (excluded by Chamuris(4) on the grounds that it is easily distinguished), 4) Stereum versicolor (Swartz: Fr.) Fr. (found in Florida and other tropical / subtropical areas), 5) Stereum styracifluum (Schwein.: Fr.) Fr. reported from Alabama and North Carolina, said to be effused to slightly reflexed and bleed yellow, regarded by Chamuris as a synonym of S. hirsutum, and 6) Stereum subtomentosum Pouzar, reported from Northwest Territories, Ontario, and Quebec, said to be effused-reflexed to stemmed and bleed yellow, regarded by Chamuris as a synonym of S. hirsutum, but suspected by Ginns(5) to be a common species, with specimens misnamed S. ostrea.

Microscopic:
SPORES 5-6.5 x 2-2.5 microns, cylindric, often slightly curved; conducting hyphae present, (Julich), SPORES 5-6.5 x 2-2.5 microns, cylindric to slightly curved, smooth, colorless, spore print white, (Lincoff), SPORES 6 x 2-2.5 microns, slightly curved, smooth, white in collection; no cystidia or gloeocystidia, in section 300-450 microns thick, composed of densely, longitudinally arranged, colorless hyphae 3-3.5 microns wide, colored conducting organs 3-3.5 microns wide occasionally present, (Burt), acuminate-tipped [sharp-tipped] HYPHIDIA would be present by virtue of the definition of the subgenus in which it is included, but not pseudoacanthohyphidia, (Chamuris(3))

Notes:
Stereum complicatum has been found in BC, the Alberta-Northwest Territories area, ON, AL, CO, DC, FL, GA, IA, IN, KY, LA, MD, ME, MI, MN, MS, NC, NH, NY, OH, PA, TN, TX, and VA, (Ginns). It also occurs in Costa Rica, El Salvador, and Brazil, (Chamuris(4)).