. Fungous diseases of plants, with chapters on physiology, culture methods and technique . to warrant bringing together the related forms as one species is generallylacking. In the determination of a species too much dependence cannot be placedupon cultural characters alone. These characters are useful, but are not suffi-ciently constant to justify exclusive use. Thus far species of Gloeosporium seem to have been definitelyconnected with three genera of Ascomycetes, as follows : Pseudope-ziza, Glomerella, and Gno-monia, the imperfect stagesof which were respectivelyknown as GloeosporiumRibis (
. Fungous diseases of plants, with chapters on physiology, culture methods and technique . to warrant bringing together the related forms as one species is generallylacking. In the determination of a species too much dependence cannot be placedupon cultural characters alone. These characters are useful, but are not suffi-ciently constant to justify exclusive use. Thus far species of Gloeosporium seem to have been definitelyconnected with three genera of Ascomycetes, as follows : Pseudope-ziza, Glomerella, and Gno-monia, the imperfect stagesof which were respectivelyknown as GloeosporiumRibis (Lib.) Mont. &Desm., Gloeosporitim fnic-tigemim Berk., and Gloeo-sporium nerviseqimm imperfect form is in-variably the importantstage from the phytopatho-•logical point of view. Theeffects upon the hosts arein every way comparableto those resulting from theattacks of various species placed in the closely related genus Colletotrichum previously de-scribed. In fact, some species of Gloeosporium occasionally pro-duce a small number of setae under special conditions. Upon the. Fig. 158. Glceosporium on Leaves ofNorway Maple 1 See Bitter Rot of the Apple, p. 271. --2 FUNGOUS DISEASES OF PLANTS twig cankers the gloeosporial stage of the apple bitter rot fungusmay produce these. Moreover, in artificial cultures species of Colle-totrichum have also yielded ascigerous stages referable to the On the other hand there is a fairly close relationshipbetween extreme forms of Colletotrichum and Volutella. In members of both Colletotrichum and Gloeosporium it has longbeen known that when conidia germinate in a drop of water on aglass slide, or under certain other conditions, structures resemblingsecondary or resting spores may be formed. Hasselbring^ hasmade a special study of these and concludes: The spore-like organs formed by the germ tubes of the anthracnoses areadhesion organs, by means of which the fungus is attached to the surface ofits host during the early s
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