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Summary: Features include 1) growth on hardwood, and occasionally conifer wood, 2) elastic, tough fruitbody that is semicircular to fan-shaped, usually shingled and forming rows, but may be resupinate, or bent outward from resupinate surface to form a shelf, 3) cap surface that is hairy-tomentose, zoned, yellow-orange to reddish brown with grayish white tomentum, with wavy surface and margin, the margin lobed and lighter in color, 4) spore-bearing surface that is grayish to yellowish, ochraceous, pale orange or orange-brown (with a whitish margin in actively growing specimens), not generally turning red when bruised, 5) spores that are narrowly elliptic to cylindric, smooth, weakly amyloid, and colorless, 6) conducting hyphae ending in pseudocystidia, and also sharp-tipped hyphidia present, 7) 2 types of hyphae, neither with clamp connections: thin-walled to thick-walled and branching, and thick-walled, branching less. 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. The Stereum hirsutum complex according to Welden(4) in 1971, referred to in Chamuris(4) in 1985, 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 or 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 being misnamed S. ostrea. The distinctions are sometimes not easy in practice - Welden(4) in 1971 despaired of differentiating Stereum complicatum and Stereum gausapatum from Stereum hirsutum because they were little different microscopically and morphological features were not dependable. Welden's solution was to synonymize the the other five taxa in the complex with Stereum hirsutum. Stereum hirsutum is found in BC, WA, OR, ID, and also AB, NB, NF, NS, NT, ON, PE, PQ, SK, AK, AL, AR, AZ, CA, CO, CT, DC, FL, GA, IA, IN, LA, MA, MD, ME, MI, MN, MO, MS, MT, NC, NH, NJ, NM, NY, OH, OK, PA RI, SC, SD, TN, TX, VA, VT, WI, WV, and WY, (Ginns(5) who recognize the members of the complex as independent species). Stereum hirsutum is common in Scandinavia (Eriksson), and found in Europe including Switzerland, and in Asia, (Breitenbach). It is also found in Mexico, Ecuador, Germany, Italy, Malawi, Uganda, and the Philippines, (Chamuris(4)).
Fruiting body: capped to semicapped, also resupinate on the underside of the substrate, caps projecting 0.5-3cm, semicircular to fan-shaped, usually coalescent to form rows and imbricate [shingled], "broadly attached and often decurrent, undulating", 0.1-0.2cm thick, co
Microscopic: SPORE 5.5-6.5 x 2-3 microns, elliptic-cylindric, smooth, weak amyloid reaction, colorless; BASIDIA 4-spored, 30-45 x 3.5-4.5 microns, narrowly clavate, without basal clamp connection; CYSTIDIA none, but cystidia-like ends of the skeletal hyphae "thick-walled, tips obtuse, 4-5 microns across (conducting hyphae)"; HYPHAE dimitic, 1) generative hyphae 2-3 microns wide, thin-walled to thick-walled, without clamp connections, 2) skeletal hyphae 3-5 microns wide, thick-walled, (Breitenbach), SPORE 5-8 x 2-4(3.5) [sic] microns, narrowly elliptic to cylindric, smooth, amyloid, thin-walled; BASIDIA 4-spored, 25-60 x 3-5 microns, elongated-clavate; CYSTIDIA of 2 types: 1) pseudocystidia "abundant, arising from the trama and forming a fairly dense layer next to the hymenium, not or rarely projecting", 7-10 microns wide and often more than 100 microns long, thick-walled except for the apical part, sometimes with "a schizopapillae" [sic], the cystidium "in the upper part filled with an oily content", [illustrated more or less cylindric], 2) acutocystidia [sharp-tipped hyphidia] numerous, 20-30 x 2-4 microns, projecting slightly "and easily observed in a thin section"; HYPHAE monomitic, simple-septate, of 2 types, "in the hymenium thin-walled to slightly thick-walled and frequently branched, in the trama thick-walled, less branched, generally 4-6 microns wide, in the cortex yellowish-brown and thick-walled, in the tomentum thick-walled and with numerous adventitious septa, often 5-8 microns wide"; hymenium may be two-layered, (Eriksson)
Habitat / Range
often covering entire trunks and branches for meters; on dead wood of hardwoods with and without bark, on standing and fallen trunks, and on attached and fallen branches; throughout the year, (Breitenbach), on hardwood but occasionally also on Picea (spruce) and Pinus (pine), (Eriksson), on many genera of hardwoods, also reported on Abies (fir), Juniperus (juniper), Larix (larch), Libocedrus decurrens (Incense-cedar), Picea (spruce), Pinus (pine), Pseudotsuga (Douglas-fir), and Tsuga (hemlock); associated with a white rot, (Ginns), all year (Buczacki)
Stereum complicatum 1) is cespitose, strongly confluent, and often imbricate (whereas S. hirsutum is single or gregarious, with some confluence), 2) the folding of the cap is radiately complicate, whereas the cap of S. hirsutum is applanate or radially undulate, and 3) has scant or appressed tomentum, so that cap surface is bald or scantily tomentose, shining, and is concentrically zonate with thin, alternating bands of orange and brownish, whereas Stereum hirsutum has thick tomentum, forming a tomentose, hirsute, strigose, or hispid cap surface that is concentrically furrowed, (Chamuris(3)); Stereum versicolor (Swartz: Fr.) Fr. - found in Florida and other tropical / subtropical areas - has scant or appressed tomentum, so that cap surface is bald or scantily tomentose, shining, and is concentrically zonate with thin, alternating bands of orange and brownish, (Chamuris(3)); Stereum gausapatum can be distinguished from members of the Stereum hirsutum complex on the bases of pseudocystidial wall thickness less than 1.5 microns (members of the Stereum hirsutum complex have pseudocystidial wall thickness greater than 1.5 microns), other characters that can be helpful are 2) Stereum gausapatum is restricted to Quercus (oak), (members of the Stereum hirsutum complex can grow on oak, but a Stereum specimen on oak is most likely to be S. gausapatum), 3) S. gausapatum usually bleeds or bruises red, while dry hymenia show dark violet or blackish stains instead, 4) caps of S. gausapatum are usually radially plicate, 5) the hymenium of S. gausapatum is buff to clay-colored, whereas that of S. hirsutum is yellow to pale orange, (Chamuris(4)); Stereum subtomentosum [regarded by Chamuris(4) as a synonym of S. hirsutum, but suspected by Ginns(5) to be a common species with specimens misnamed S. ostrea] is "similar but well distinguished by usually larger and more spathulate fruitbodies with a softer and more adpressed and velutinous tomentum" (in Scandinavia restricted to alder), (Eriksson); Stereum ostrea differs microscopically from the Stereum hirsutum group [having pseudoacanthohyphidia for instance] "but can usually be told by its slightly larger caps" ( 1-7cm broad) "that are more prominently zoned (dark reddish and brown) and usually form individual brackets rather than fusing, and buff to cinnamon-buff underside", (Arora); Pseudochaete tabacina resembles the S. hirsutum group in shape and color, but its tissue blackens in KOH, (Arora)
Recommended citation: Author, Date. Page title. In Klinkenberg, Brian. (Editor) 2020. E-Flora BC:
Electronic Atlas of the Plants of British Columbia [eflora.bc.ca]. Lab for
Advanced Spatial Analysis, Department of Geography, University of British
Columbia, Vancouver. [Accessed:
2021-04-16 8:05:41 PM
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