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Page number:111 
Description type:Non-original description 
Description:Stereum ochraceo-flavum (Schwein.) Ellis, North American Fungi, no. 17. 1878.
Basionym: Thelephora ochraceo-flava Schwein., Trans. Amer. Philos. Soc. (n.s.) 4:167. 1832.
= Stereum striatum (Fr. : Fr.) Fr. var. ochraceo-flavum (Schwein.) Welden, Mycologia 63:797. 1971.
= Stereum vellereum Berkeley, Fl. nov.-zel. 2:183. 1855.
= Stereum sulphuratum Berkeley & Ravenel, in Berkeley and Curtis, J. Linn. Soc., Bot. 10:331. 1868.
= Stereum rameale (Berkeley) Massee, J. Linn. Soc., Bot. 27:187. 1890. Not S. rameale (Schwein.) Burt = S. hirsutum complex.
Basidiomata annual; effuso-reflexed, usually umbonate; confluent, sometimes imbricate. Reflexed parts conical to flabelliform; applanate to undulate; up to 1.5 x 2.5 (-3) cm in temperate zone. Upper surface strigose-hirsute, villose, often hispid on umbo; soft; indistinctly zonate and furrowed; white, grayish-white, seldom grayish orange (5B3-4), dark gray when old and weathered. Hymenial surface even, occasionally with a few concentric ridges, rarely tuberculate, effused parts with a central wart; light orange (5A4-5), orange (5A6), grayish orange (5B4-5, 6B4), brownish orange (5C5), rarely light brown (6D5) to brown (6E8), yellow when fresh.
Conducting hyphae thick-walled; with hyaline or pale yellow, globular contents; 4-8 µm diam. In section 150-400 µm thick; tomentum up to 1 mm thick. Cutis absent; occasionally a poorly defined, pale yellow zone may form on old specimens. Context subhyaline, pale yellow to yellow brown. Hymenium thickening slightly, not stratose; usually with embedded crystals. Pseudocystidia cylindrical to subcylindrical; thick-walled at base, thin-walled apically; with hyaline to yellow, globular contents; 4-11 µm diam. Hyphidia acuminate; thin-walled; 2-3 µm diam. Basidia narrowly clavate to subcylindrical; 4-sterigmate; basal clamp absent; 25-35 x 4-4.5 µm. Basidiospores ellipsoid to cylindrical, sometimes curved; hyaline; smooth; thin-walled; amyloid; 2-nucleate; 5-7.5 (-8) x 1.5-2.5 µm.
Distribution: A widespread but principally southern species; in eastern United States, generally south of 43 N. Known as S. sulphuratum and S. rameale in Europe, S. sulphuratum in the neotropics, and S. vellereum in Australasia.
Discussion: Stereum ochraceo-flavum can be recognized by the small, umbonate to subcupulate basidiomata, well-developed grayish white tomentum, yellow hymenial surface, and lack of a distinct cutis. Also, S. ochraceo-flavum displays a preference for small limbs, usually less than 3 cm diam.
Stereum ochraceo-flavum is similar to S. striatum, but differs in possessing a well-developed tomentum, and in its absence on Carpinus caroliniana, the common host of S. striatum. Meruliopsis corium, when reflexed and young, can be mistaken for S. ochraceo-flavum in the field. Meruliopsis corium, however, has a ceraceous, merulioid hymenium, inamyloid basidiospores, and no pseudocystidia.
Large specimens of S. ochraceo-flavum may be mistaken for small, cupulate specimens of S. hirsutum. Stereum hirsutum, however, has yellow or brown pigments in the tomentum, and possesses a cutis easily observed with a hand lens.
Another species that may be confused with S. ochraceo-flavum in the field is Aleurodiscus oakesii, which differs in having ornamented basidiospores, acanthohyphidia and moniliform hyphidia. Also, A. oakesii is nearly always found on trunks and larger limbs, while S. ochraceo-flavum prefers small-diameter limbs.
Descriptions and illustrations: Bourdot & Galzin (1928); Breitenbach & Kränzlin, 1986; Cunningham, 1963; Burt, 1920; Davydkina, 1980; Jung, 1987; Killermann, 1943; Lentz, 1955; Overholts, 1939; Pilát, 1930.
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