Nature and development of plants . me mycelium forms in the leavesof the wheat quite a different type of spore. They are formed inthe same manner as the uredospores but are provided with thickdark walls and from one to several spores are developed at theend of the hyphae (Fig. 160, D). Consequently, when the epider-mis is ruptured, these spores form rusty black blotches on theleaves. This third stage is known as the telial, since it ends theseasons growth. These spores, called teleutospores, are restingspores and tide the fungus over the winter. They germinatein the spring quite independent of
Nature and development of plants . me mycelium forms in the leavesof the wheat quite a different type of spore. They are formed inthe same manner as the uredospores but are provided with thickdark walls and from one to several spores are developed at theend of the hyphae (Fig. 160, D). Consequently, when the epider-mis is ruptured, these spores form rusty black blotches on theleaves. This third stage is known as the telial, since it ends theseasons growth. These spores, called teleutospores, are restingspores and tide the fungus over the winter. They germinatein the spring quite independent of any plant and being dependentupon the food stored in the spore, they only form short hyphaewhich usually become divided into four cells (Fig. 161, B).This structure is known as the basidium. Each cell of the basi- 224 LIFE HISTORY OF A RUST dium sends out a delicate tube into the end of which the cellcontents passes, thus forming a small spore, known as the basidio-spore. This basidial stage completes the life history of the fun-. Fig. 160. Fig. 161. Fig. 160. The summer and fall stages of a rust, Puccinia: A, rustblotches on leaf of wheat. B, portion of leaf magnified, showing rupturingof the epidermis due to the formation of spores. C, uredospores or thesummer spores which effect a rapid distribution of the parasite during thesummer. D, teleutospores or fall spores which are dormant during thewinter. Fig. 161. Germination of uredo- and teleutospores: A, the thin-walleduredospore sending out hyphae from thin places in its wall. This is ef-fected as soon as it is carried by the wind to a moist leaf. B, teleutosporegerminating in the spring and forming a short hypha, from the end ofwhich four cells have been cut off that are forming the basidiospores, b. gus for the basidiospores are carried to the leaves of the barberryand begin again the life cycle of the parasite by forming thecluster cups. It is not surprising that this story was not unravelled for along time and that these
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