. Botany for agricultural students . Botany. THE GRAPE DOWNY MILDEW (PLASMOPARA VITICOLA) 355 fertilization forms an oospore which can germinate. This peculiar feature, called parthenogenesis, meaning reproduction by an egg without fertilization, has been mentioned before (page 50). The aquatic habit, reproduction by zoospores, and character of sex organs support the theory that the Water Molds are degenerate forms with the Green Algae as their ancestors. The. Fig. 306. — Leaf of the Grape, showing the downy areas caused by the Downy Mildew, Plasmopara Vilicola. After W. H. Hein. coenocytic ch
. Botany for agricultural students . Botany. THE GRAPE DOWNY MILDEW (PLASMOPARA VITICOLA) 355 fertilization forms an oospore which can germinate. This peculiar feature, called parthenogenesis, meaning reproduction by an egg without fertilization, has been mentioned before (page 50). The aquatic habit, reproduction by zoospores, and character of sex organs support the theory that the Water Molds are degenerate forms with the Green Algae as their ancestors. The. Fig. 306. — Leaf of the Grape, showing the downy areas caused by the Downy Mildew, Plasmopara Vilicola. After W. H. Hein. coenocytic character of their hyphae suggests a close relationship with the Siphonales. Downy Mildews (Peronosporales). — These Fungi, which are parasites on the higher plants, cause some serious plant diseases of which the Grape Downy Mildew and Potato Blight are notable ones, and will serve to illustrate the habits of the group. There are about 100 species known and the order is so named because of the downy patches which they produce on the diseased portions of the host. The Grape Downy Mildew (Plasmopara Viticola). — The Downy Mildew of the Grape, shown in Figure 305, is a very. 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 Martin, John N. (John Nathan), b. 1875. New York : John Wiley & Sons, Inc.
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbotany, bookyear1919
