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Remarks (internal):This species is the type of the name Helminthosporium Link ex Fries (nom. cons.. Fries. Syst. Mycol. I: xlvi.1821. as 'Helmisporium'). Several synonyms of the species were listed by Hughes (Can. J. Bot. 36:775. 1958, as Helmisporium ciliare (Pers.) Hughes) and by Ellis (Mycol. Papers 82:14. 1961). The production of conidia at apparent pores in Helminthosporium and in some other genera was discussed by Hughes (Can. J. Bot. 31: 577-659. 1953). A large number of species described in this genus do not show the distinctive conidium production on determinate conidiophores as in the type species and have been relocated in other genera. Helminthosporium is currently being used in a restricted sense for only about a dozen species: Ellis (op. cit.) published illustrations and descriptions of ten species. including H. solani Durieu & Mont.. the cause of 'silver scurf' of potato, which has most commonly been referred to as Spondylocladium atrovirens (Harz) Harz ex Sacc.
The collection listed above from Manitoba was recorded as 'H. macrocarpon Grev. (or a variety)' by Bisby et al. (The Fungi of Manitoba. p. 127. Longman Green & Co. 1929): II. macrocarpum Grev. is now considered a synonym of H. velutinum (Ellis, op. cit.). It appears likely that H. velutinum is widespread in North America. Ellis (op. cit.) recorded the species from Georgia and Pennsylvania in U.S.A.
Description type:Non-original description 
Description:Helminthosporium velutinum Link ex S.F. Gray. Link, Mag. Ges. naturf. Freunde, Berlin, 3: 10. 1809, as `Helmisporium'; S.F. Gray, Nat. Arr. Br. Plants, p. 557, 1821, as `Helmisporium'.
Colonies effuse, black, hairy to velutinous to tufted. Mycelium immersed, composed of branched, septate, subhyaline to brown hyphae 2-7.5 µm wide. Stromata partly superficial partly immersed, rudimentary and composed of about 15 brown to dark brown cells, or well developed and usually erumpent through periderm, up to 200 µm wide but larger by confluence and composed of brown to dark brown pseudoparenchymatous cells up to 12 µm wide. Conidiophores scattered or crowded, arising singly or in small groups from the rudimentary stromata or in dense fascicles of up to about 100 from the larger stromata. They are simple, straight or flexuous. 145-1100 µm long and 18-23.5 µm wide above the basal cell which, in robust conidiophores, may be swollen up to 27 µm wide: conidiophores are more or less cylindrical, tapering gradually toward the rounded apex which is 9-1 1.5 µm wide. They are septate at 30-45 µm intervals, dark brown to almost black and thick-walled (up to 5 µm) at the base, brown and thinner-walled (about 1 µm) toward the apex. Conspicuous `pores' in the wall toward the distal end of the conidiophore indicate the position at which solitary, readily seceding conidia have developed. The apex of the conidiophore bears 1-3 such pores and 1-3 similar pores usually below the septa of a series of 3-9 cells below the apical one so that undisturbed conidiophores hear terminal conidia and solitary or verticils of conidia below the distal cell. Conidia obclavate, sometimes rostrate, straight or flexuous, smooth but occasionally wrinkled with age, subhyaline to brown, paler toward the apex and dark brown to black around the base which is rounded or sometimes slightly truncate. The lateral wall is up to 5.5 µm wide in the broader part of the conidium but thinner toward the apex especially when long and tapered. They are 6-17-pseudoseptate with the lumina usually angular in outline and some septa have a conspicuous central dark lamella; longitudinal septa are rare. Conidia are variable in size, being 41-160 x 12.5-20 µm, mostly 55-80 x 14-17 µm: rostrate conidia are 3.8-6.3 µm wide at their distal end.
Substrate: Dead wood and bark of Acer macrophyllum, A. saccharum, Alinus rubra, Betula papyrifera, Cornus nuttallii, C. stolonifera, Corylus, Cytisus scoparius, Quercus macrocarpa, Rubus, Sambucus pubens, Spiraea douglasii, Ulmus, and of unidentified hardwood trees.
Distribution: Quebec. Ontario, Manitoba. British Columbia.
Taxon name: