. Fungi, ascomycetes, ustilaginales, uredinales. Fungi. ^B Ervsiphales The Erysiphales are characterized by an abundant superficial mycelium, which may be white (colourless) or dark-coloured. The perithecia are spherical, ovoid or flattened, and are usually without an ostiole; the peridium is thin and membranous; the asci are arranged in a regular layer at the base of the perithecium. The group includes some 600 species, the majority of which are external parasites or epiphytes upon the leaves of higher plants. They are grouped into three families, of which the Microthyriaceae are but little k
. Fungi, ascomycetes, ustilaginales, uredinales. Fungi. ^B Ervsiphales The Erysiphales are characterized by an abundant superficial mycelium, which may be white (colourless) or dark-coloured. The perithecia are spherical, ovoid or flattened, and are usually without an ostiole; the peridium is thin and membranous; the asci are arranged in a regular layer at the base of the perithecium. The group includes some 600 species, the majority of which are external parasites or epiphytes upon the leaves of higher plants. They are grouped into three families, of which the Microthyriaceae are but little known, and of doubtful position, and the Erysiphaceae and Perisporiaceae show several points in common both with the Plectascales, from which they differ in the regular arrangement of their asci, and with the Pyre- nomycetes, from which they are for the most part distinguished by the absence of an ostiole. Their taxonomic position is probably somewhere between these two groups, and they have, under various systems of classifi- cation, been placed in closer proxi- mity sometimes to the one and sometimes to the other. Their in- clusion here in the Plectomycetes is due to the fact that they, or rather their best-known family, the Erysiphaceae, show indica- tions of being a primitive group. The simple type of male and female organs, the latter without a trichogyne, and the simple structure of the perithecium are evidence in this direction. The families of the Erysiphales may be distinguished as follows : Aerial mycelium colourless (or white). Perithecia more or less globose without an ostiole, furnished with conspicuous appendages. Conidia of oidium type. Fig. 37. Terfezia olbiensis Tul.; section through hymenium, showing asci irregularly arranged; after Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the or
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectfungi, bookyear1922
