. Botany for secondary schools; a guide to the knowledge of the vegetation of the neighborhood. Plants. 355. Leaf of barberry with cluster-cups. a cross-section of one of the cups, outlining the long chains of spores, and the mycelium in the tissues. The aecidiospores are formed in the spring, and after they have been set free some of them lodge on wheat or other grasses, where they germi- nate immediately. The germ-tube enters the leaf through a stomate, whence it spreads among the cells of the wheat plant. The aecidiospores are not able to infect the barberry leaf. During summer one-celled u
. Botany for secondary schools; a guide to the knowledge of the vegetation of the neighborhood. Plants. 355. Leaf of barberry with cluster-cups. a cross-section of one of the cups, outlining the long chains of spores, and the mycelium in the tissues. The aecidiospores are formed in the spring, and after they have been set free some of them lodge on wheat or other grasses, where they germi- nate immediately. The germ-tube enters the leaf through a stomate, whence it spreads among the cells of the wheat plant. The aecidiospores are not able to infect the barberry leaf. During summer one-celled uredospores ("blight spores") are produced in a manner similar to the teleutospores. The sori bearing them are red, due to the color of the spores of the mass. These are capable of germinating immediately and serve to disseminate the fungus during the summer on other wheat plants or grasses. (Fig. 357.) Late in the season, teleutospores are again produced, completing the life cycle of the plant. Many rusts besides Puccinia graminis produce different spore-forms on different plants. The phenom- enon is called heteroecism, and was first shown to exist in the wheat rust. Curiously enough, the peasants of Europe had observed and asserted that barberry bushes cause wheat to blight long before science explained the relation be- tween the cluster-cups on barberry and the rust on wheat. The true relation was actually demonstrated, as has since been done for many other rusts on their respective hosts, by sowing the aecidiospores on healthy wheat plants and thus pro- ducing the rust. The cedar apple is another rust, the fungus producing the curious swellings often found on the branches of red cedar trees. In the spring the teleutospores ooze out from the "apple" in brownish yellow masses. It has been found that these attack various pomaceous fruit trees pro- ducing fficidia on their leaves. Cedar t/ees about orchards may be a menace unless carefully Please no
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectplants, bookyear1913
