. Lessons in botany. Botany. 132 BOTANY. The walls are thinner and not so dark in color, and they are covered with minute spines. They have also short stalks, but •e^gj^ these fall away very easily. These one- MSwIiSl^ celled spores of the red-rust form are called '' uredospores.'' The uredospores and teleutospores are sometimes found in the same pustule. It was once supposed that these two kinds of spores belonged to different plants, but now it is known that the one-celled form, the uredospores, is a form developed earlier in the season than the teleu- tospores. 223. Cluster- cup form on the
. Lessons in botany. Botany. 132 BOTANY. The walls are thinner and not so dark in color, and they are covered with minute spines. They have also short stalks, but •e^gj^ these fall away very easily. These one- MSwIiSl^ celled spores of the red-rust form are called '' uredospores.'' The uredospores and teleutospores are sometimes found in the same pustule. It was once supposed that these two kinds of spores belonged to different plants, but now it is known that the one-celled form, the uredospores, is a form developed earlier in the season than the teleu- tospores. 223. Cluster- cup form on the barberry. —On the bar- berry is found still another of the. Fig. no. Barberry leaf with two diseased spots, natural size. Figures 153-135. Fig. in. Single spot showing cluster cups enlarged. split margin -Cluster-cup stage of "wheat rust. Two cluster form cups more en- larged, showing wheat rust, the sniit marcrin. ' cluster cup '' stage. The pustules on the under side of the barberry leaf are cup-shaped the cups being partly sunk in the tissue of the leaf, while the rim is more or less curved backward against the leaf, and split at several places. These cups occur in clusters on the affected spots of the barberry leaf as shown in fig. 111. Within the cups numbers of one-celled spores (orange in color, called aecidiospores) are borne in chains from short branches of the mycelium, which fill the base of the cup. In fact the wall of the cup (peridium) is formed of similar rows of cells, which, instead of separating into spores, remain united to form a wall. These cups are usually borne on the under side of the 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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