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Remarks (public):For a complete description including images see 
Remarks (internal):This saprophyte is one of the commonest causes of zone lines (often very distinctive) in wood. The white rot produced has numerous black zone lines which have been described in detail by Campbell who also gives an account of the cultural characteristics. Beech blocks at 22ºC lost 14% of their weight and the optimum temperature for growth is 27ºC. The production of an inhibitory substance by X. polymorpha has been described (43, 1255).
Description type:Non-original description 
Description:Xylaria polymorpha (Pers.) Grev., Fl. edin.: 355. 1824.
= Sphaeria polymorpha Pers., 1797.
= Xylosphaera polymorpha (Pers.) Dumortier, 1822.
= Xylaria protea Fr., 1851.
= Xylaria schweinitzii Berk. & M.A. Curtis, 1953.
= Xylaria corrugata Har. & Pat., 1903.
= Xylaria ophiopoda Sacc., 1906.
= Xylaria rugosa Sacc., 1906.
= Sphaeria obovata Berk., 1839.
= Xylaria obovata (Berk.) Fr., 1851.
Stromata solitary or in clusters, black, clavate to irregular or even lobed at the tip, 3-9 cm high or more and 1-5 cm wide, short-stalked, rounded at the apex; surface hard, crusty, smooth or cracking into minute ill-defined scales; internally composed of a white to pale buff, solid mass of indistinct fleshy structure; when dry the flesh becomes somewhat wrinkled; the young stromata covered with a layer of light brown conidia. Perithecia arranged immediately beneath the surface, 700-800 µm diam., with distinct papillate ostioles which project as conical tips on the surface; wall 20-25 µm thick, composed of few layers of brown cells 2 µm wide. Asci long-stalked, cylindrical, unitunicate, 8-spored, 170-220 x 5-12 µm, with an apical apparatus blued by iodine. Ascospores monostichous, non-septate, dark brown. fusoid with one side flattened, 20-32 x 5-12 µm, generally guttulate and with a germ slit.
Conidiophores closely packed on the surface of the stroma in a palisade layer, often dichotomously branched towards the apex, pale to dark brown, smooth or slightly verruculose. Conidiogenous cells 4,5-5 µm wide, polyblastic, integrated and terminal or discrete, cylindrical to clavate, rounded at the apex, denticulate, denticles very delicate. Conidia solitary, dry, simple, acropleurogenous, ellipsoidal or obovoid or occasionally clavate, truncate at the base, hyaline to brown or olivaceous brown, smooth or sometimes verruculose, 7-11 x 3,5-5 µm.
Hosts: Mostly gregarious on stems of deciduous trees, including Acer rubrum, Coffea arabica, Platanus acerifolia and Shorea robusta.
Disease: Causes decay of stumps and fallen timber of hardwoods. At most a weak pathogen which enters through wounds. It has been associated with Acer rubrum (17: 357). Coffea arabica (7: 538), Platanus acerifolia (36: 288) and Shorea robusta (33: 58), as well as other hosts.
Geographical distribution: Widespread.
Physiological specialization: No studies reported.
Transmission: No studies reported.
Literature: Dennis, Kew Bull. 1956 (3): 438, 1957 (taxonomy); Dennis, Revista de Biologia 1: 200, 1958 (taxonomy); Campbell, Ann. appl. Biol. 20: 123-145, 1933 (development on artificial media and wood blocks).

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