. Lessons in botany. Botany. '3° BOTANY. pare in the same way from the yellow spots. To demonstrate the cluster cups, good cross-sections of the leaf through a spot should be made, or prepared slides should be obtained. Let the pupils sketch the form of the different spores, and other characters, and make notes of the observations. To demonstrate mycelium in the tissues, use the carnation rust which can be obtained in winter in greenhouses where the carnations are grown (see Chapter XV, paragraph 159), or fresh wheat leaves may be preserved in alcohol for making sections. 220. Wheat rust (Pucc
. Lessons in botany. Botany. '3° BOTANY. pare in the same way from the yellow spots. To demonstrate the cluster cups, good cross-sections of the leaf through a spot should be made, or prepared slides should be obtained. Let the pupils sketch the form of the different spores, and other characters, and make notes of the observations. To demonstrate mycelium in the tissues, use the carnation rust which can be obtained in winter in greenhouses where the carnations are grown (see Chapter XV, paragraph 159), or fresh wheat leaves may be preserved in alcohol for making sections. 220. Wheat rust (Puccinia graminis).—The wheat rust is one of the best known of these fungi, since a great deal of study has been given to it. One form of the plant occurs in long. \ Fig. 102. "Wheat leaf with red rust, natural size. Mg. 106 Single sorus. Fig. 103. Fig. 104. Fig. 105. Portion of leaf Black rust. Enlarged, enlarged to show Natural size, sori. Figures 102, 103.—Puccinia graminis, red rust stage (uredo stage). Figures 104-106.—Black rust of wheat, showing son of teleutospores. reddish-brown or reddish pustules, and is known as the " red rust" (figs. 102, 103). Another form occurs in elongated black pustules, and this form is the one known as the " black rust" (figs. 104-107). These two forms occur on the stems, blades, etc., of the wheat, also on oats, rye, and some of the grasses. 221. Teleutospores of the black-rust form.—Scrape off some portion of one of the black pustules (sori), tease it out in water on a slide, and examine with a microscope, to see numer-. 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 Atkinson, George Francis, 1854-1918. New York, H. Holt and company
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