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Remarks (public):For a complete description including images see 
Remarks (internal):Control on Camellia is by pruning diseased stems and painting frames with antimucin (43, 558). If all infected parts are not removed by pruning the disease continues to spread (47, 621b). All diseased tissue removed should be taken away and burnt (42: 402). The var. effusum (Nits.) J.H. Miller (= H. effusum Nits.) with slightly smaller ascospores (8-10 x 4-5 µm) is rarer than var. serpens; and var. macrospora J.H. Miller with larger ascospores (13-22 x 5-8 µm) is also rare and restricted to North America. Martin (1968) regards H. caries (Schwein.) Sacc. as a small form of H. serpens. Hypoxylon serpens is unlikely to be confused with any other species of its genus.
Description type:Non-original description 
Description:Hypoxylon serpens (Pers.: Fr.) Kickx, Flore cryptogamique des environs de Louvain: 115, 1835.
= Sphaeria serpens Pers.: Fr., Systema mycologicum 2: 341, 1823.
= Sphaeria serpens Pers., Annls Bot. (Usteris) 9: 18, 1795.
= Haplaria grisea auct., non Link, 1809.
= Geniculosporium serpens Chesters & Greenhalgh, 1964. Stat. conid.
For further synonyms see Miller (1961, pp. 77-78).
Stromata superficial or erumpent through bark, discrete to effuse, often forming extensive patches 1-1,5 mm thick, surface whitish-grey at first, becoming bronze and finally dark purplish-brown to black when mature, smooth but with conspicuous projecting perithecia, matt to slightly nitid, carbonaceous. Perithecia projecting from the stroma, usually numerous, globose to ovate, 0,5-1 mm diam., rarely to 1,5 mm high, ostioles papillate. Asci subcylindrical to cylindrical, stalked, 8-spored, 65-130 x 5-10 µm, stalk 30-70 µm high. Paraphyses numerous but gelatinizing at maturity, simple, filiform, sparsely septate, 2-4 µm wide. Ascospores uniseriate, inequilaterally ellipsoid, brown to dark brown with a longitudinal furrow which may be indistinct, 10-17 x 5-8 µm. Conidial state Geniculosporium serpens forming greyish patches up to 0,3 mm high on decorticate wood. Cultures on MA growing moderately slowly at 25ºC, whitish-grey to brownish above, partly submerged, aerially weakly flocculose. Conidiophores pale brownish below but becoming hyaline above, irregularly sparsely branched, to 320 µm high, 2-4,5 µm wide. Conidia arising on geniculations from the conidiogenous cells, hyaline to very pale fuscous, simple, obovoid to ellipsoid, with a minute basal frill, 2,5-6 x 1,5-3 µm.
Hosts: On wood of many genera of dicotyledonous trees, including decorticate logs and stumps. In Europe it is particularly common on Fagus sylvatica and Camellia sinensis in Ceylon and India.
Diseases: Cause of wood rot of economic importance in Camellia sinensis in Ceylon and India (47, 2655; 49, 2170) which leads to a gradual decline of the plant. It also attacks a wide range of dicotyledonous trees, but most of these are not economically important.
Geographical distribution: Cosmopolitan in temperate and subtropical regions; particularly common in Europe.
Physiological specialization: None known.
Transmission: Presumably by ascospores and conidia in wind entering through wounds or landing on other decorticate parts of the hosts.
Literature: Miller, A Monograph of the World Species of Hypoxylon, 1961 (taxonomy); Martin, Jl S. Afr. Bot. 33: 315- 328, 1967; 34: 153-199, 1968 (taxonomy); Chesters & Greenhalgh, Trans. Br. mycol. Soc. 47: 393-401, 1964 (conidial state).

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