. Beginners' botany. Botany. (Fig. 276). These patches consist of numerous interwoven threads that may be recognized under the microscope as the mycehum of the fungus. The mycehum in this case hves on the surface of the leaf and nour- ishes itself by sending short branches into the cells of the leaf to ab- sorb food materials from them. Numerous summer-spores are formed of short, erect branches all over the white surface. One of these branches is shown in Fig. 277. When it has grown to a cer- tain length, the upper part begins to segment or divide into spores which fall and are scattered by th
. Beginners' botany. Botany. (Fig. 276). These patches consist of numerous interwoven threads that may be recognized under the microscope as the mycehum of the fungus. The mycehum in this case hves on the surface of the leaf and nour- ishes itself by sending short branches into the cells of the leaf to ab- sorb food materials from them. Numerous summer-spores are formed of short, erect branches all over the white surface. One of these branches is shown in Fig. 277. When it has grown to a cer- tain length, the upper part begins to segment or divide into spores which fall and are scattered by the wind. Those faUing on other wil- lows reproduce the fungus there. This process continues all summer, but in the later part of the season provision is made to maintain the mildew through the winter. If some of the white patches are closely ex- amined in July or August, a number of Httle black bodies will be seen among the threads. These little bodies are csHA&, shown in Fig. 278. To the naked eye they appear as minute specks, but when seen under a magnifi- cation of 200 diameters they present a very interesting appear- ance. They are hollow spheri- cal bodies decorated around the outside with a fringe of crook-like hairs. The resting-spores of the willow mildew are produced in sacs or (jij'cnn- closed witli- in the leath- ery perithecia. Figure 279 shows a cross-section of a perithecium with the asci arising from the bottom. The spores remain securely Fig. 277. — Summer-spores of Willow 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 Bailey, L. H. (Liberty Hyde), 1858-1954. New York, The Macmillan company
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Keywords: ., bookauthorbai, bookcentury1900, bookdecade1900, booksubjectbotany
