. Botany; principles and problems. Botany. THE THALLOPIIYTA 295 a hymenium and opening to the air by a minute pore. Here belong the knot and wart fungi found on so many woody plants, many of which, such as the "black knot" of plums (Fig. 170), are serious parasites. In this order also occur the destructive chestnut bark fungus and other important disease-producing organisms. 3. Perisporiales or Mildews.—These small fungi produce a cobweb-like mycelium which spreads over the surface of the. Fig. 171.—Aspergillus {A) and Peni- cillium (B). Hyphae bearing chains of air-spores or conidia
. Botany; principles and problems. Botany. THE THALLOPIIYTA 295 a hymenium and opening to the air by a minute pore. Here belong the knot and wart fungi found on so many woody plants, many of which, such as the "black knot" of plums (Fig. 170), are serious parasites. In this order also occur the destructive chestnut bark fungus and other important disease-producing organisms. 3. Perisporiales or Mildews.—These small fungi produce a cobweb-like mycelium which spreads over the surface of the. Fig. 171.—Aspergillus {A) and Peni- cillium (B). Hyphae bearing chains of air-spores or conidia. (From Strasburger). Fig. 172.—Yeast (Saccharo- myccs). Single-celled plants in various stages of division by budding. leaves of many plants and is parasitic on their epidermal cells. Conidia are produced in abundance. Toward the end of the season, as the result of a sexual union between female branches (ascogonia) and antheridia, there are developed a host of minute, dark, globular, and hard-walled ascocarps or perithecia. These are filled with asci, and on breaking open the next spring, release the ascospores. 4. Plectascales the Blue and Green Molds (Fig. 171).—Here are found the common molds (aside from the Mucorales) which appear on bread, cheese, leather, and almost all organic substances which will "mold" when subjected to dampness. Their abundant masses of conidia arc typically greenish or bluish in color. Small, rounded ascocarps, full of irregularly scattered asci and lacking a hymenium, are occasionally produced. No members of the order are parasitic, but a species of PeniciUium is of economic impor- tance as responsible for the peculiar flavor of Roquefort cheese. 5. Saccharomycetes or Yeasts (Fig. 172).—These minute plants are usually included within the ascomycetes. The individual is a. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectbotany, bookyear1923
