E-Flora BC: Electronic Atlas of the Flora of British Columbia

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.

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)).

Fruiting body:
effused-reflexed [bent outward to form shelf-like cap] to flabelliform [fan-shaped], reflexed part radiately plicate [pleated]; cap surface "strigose or appressed silky-strigose, cinnamon-buff to hazel", sometimes grayish; spore-bearing surface "cream-buff to cinnamon-buff to orange", even, (Julich), 0.3-1.5cm across, "fan-shaped or semicircular, with a wavy margin"; cap surface "pinkish or orangish to cinnamon fawn or grayish, with a paler whitish margin", "silky-hairy, concentric zones and furrows, smooth and shiny near margin", spore-bearing surface "orange, fading to cream-fawn or cinnamon-fawn, smooth or slightly ridged where caps meet", (Phillips), 0.3-1.5cm across, "often overlapping or laterally fused, fan-shaped or semicircular"; cap surface "pinkish to cinnamon-buff or grayish", "silky-hairy, zoned, radially furrowed to wavy, smooth and shining near margin"; spore-bearing surface orange, fading to cream-buff or cinnamon-buff, "smooth or slightly ridged where caps join"; flesh 0.03-0.04cm thick, (Lincoff), effuso-reflexed (rarely resupinate), leathery, thin, rigid, the reflexed part consisting of small, umbonate caps that are sometimes subdivided into lobes, the caps or lobes drying folded together or crisped; sometimes covering areas only 0.5-1cm across, and gregarious, at other times irregularly confluent over areas up to 3cm wide and 10cm or more long, individual caps 0.2-1cm wide, 0.3-1cm long; cap surface cinnamon-buff to hazel, more or less zoned, fibrose-strigose, becoming bald on the marginal part, shining, with innate fibers radiating from the base; spore-bearing surface light buff to cream-buff, even, bald, (Burt), may bruise red, but microscopic examination of radial sections reveal that the conducting hyphae do not possess the brownish contents typical of S. gausapatum, (Chamuris(4))

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))