. A text-book of botany for secondary schools. Botany. FUNGI 143 From this internal mycelium numerous sporophores arise and reach the surface of the leaf; and many of them rising above the surface close together, they form little velvety patches sug- gesting the name downy mildew. These sporophores, after rising above the surface of the leaf, branch freely and produce spores (Fig. 132). The spores are scattered by the wind, fall upon other leaves, and start new my- celia, which penetrate into the tissues of the leaf and begin their ravages. In this way the parasite spreads with great rapidity,
. A text-book of botany for secondary schools. Botany. FUNGI 143 From this internal mycelium numerous sporophores arise and reach the surface of the leaf; and many of them rising above the surface close together, they form little velvety patches sug- gesting the name downy mildew. These sporophores, after rising above the surface of the leaf, branch freely and produce spores (Fig. 132). The spores are scattered by the wind, fall upon other leaves, and start new my- celia, which penetrate into the tissues of the leaf and begin their ravages. In this way the parasite spreads with great rapidity, often producing seri- ous epidemics among plants. In certain conditions special branch- es arise from the mycelium which bear antheridia and oogonia that remain within the host (Fig. 133). The oogo- nium develops a single egg. The an- theridium comes into contact with it, puts out a tube that pierces the oogo- nium wall, and discharges its contents (Fig. 133, B). As a result of this act. Fig. 132,—Sporophores oi a PeroTioapora fcrm ris^ ing through the stomat^ of the host-leaf (potato), branching, and bear- ing spores; this form causes potato-rot.—Aft- er 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. New York, D. Appleton
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectbotany, bookyear1906
