. A textbook of botany for colleges and universities ... Botany. 76 MORPHOLOGY Black fungi. —This (Pyrenomycetes proper) is an exceedingly large and varied group, characterized by a flask-shaped ascocarp opening at the top (perithecium) and lined by the hymenial layer of asci and hair- like paraphyses (fig. 184). It includes parasites on various parts of plants, especially cortex and leaves; and also saprophytes on decaying wood, etc., often forming black spots, knots, etc., resembling charred places and suggesting both the technical and common names. The peri- thecia arise either singly on th
. A textbook of botany for colleges and universities ... Botany. 76 MORPHOLOGY Black fungi. —This (Pyrenomycetes proper) is an exceedingly large and varied group, characterized by a flask-shaped ascocarp opening at the top (perithecium) and lined by the hymenial layer of asci and hair- like paraphyses (fig. 184). It includes parasites on various parts of plants, especially cortex and leaves; and also saprophytes on decaying wood, etc., often forming black spots, knots, etc., resembling charred places and suggesting both the technical and common names. The peri- thecia arise either singly on the mycelium (as in Plowrightia), appearing. 181 Ijy 182 Figs. i8t, 182. — Mildews: 181, ascocarp of Microsphaera, showing the heavy case, dichotomous appendages, and asci crushed out of the case; 182, ascocarp of UnciniUa, with hooked appendages. as small black dots irregularly scattered, as in the mildews; or they occur in groups embedded in a variously shaped mass of compact (paren- chyma-like) mycelium, the whole structure being known as the stroma (pi. stromata). A single illustration of each kind will be given. Black knot {Plowrightia morhosa).—This is a destructive disease that attacks the plum and cherry (fig. 1100). In the spring the mycelium is under the bark; then it breaks through, beginning the knot, which may become quite large and solid, composed of the mycelium of the parasite and hypertrophied host tissue. Numerous sporophores arise from the mycelium, abstricting conidia ; and in the autumn the perithe- cia appear over the surface of the knot as small papillae, open at the top and lined with a hymenial layer. In the following spring the ascospores escape and begin fresh 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 original Coulter, John Merle, 1851-1928; Barnes, Charles Reid, 1858
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