. Fungous diseases of plants, with chapters on physiology, culture methods and technique . measure20-36 X 14-20/x. Paraphyses are abundant. Tranzschel deter-mined that uredospores kept over winter at St. Petersburg werecapable of germination the following spring. The teleutospores generally appear in small groups among theuredospores and later supplant these entirely. The pustules aregenerally pulverulent and chestnut-brown. The teleutospores arefrom very light to reddish brown upon the different hosts. Ingeneral form they are elliptical, deeply constricted, and the twocells are more or less e
. Fungous diseases of plants, with chapters on physiology, culture methods and technique . measure20-36 X 14-20/x. Paraphyses are abundant. Tranzschel deter-mined that uredospores kept over winter at St. Petersburg werecapable of germination the following spring. The teleutospores generally appear in small groups among theuredospores and later supplant these entirely. The pustules aregenerally pulverulent and chestnut-brown. The teleutospores arefrom very light to reddish brown upon the different hosts. Ingeneral form they are elliptical, deeply constricted, and the twocells are more or less equal, often subspherical. They separatereadily. These spores are provided with pointed tubercles. Thespores measure 32-44 x 20-26 ix. The pedicels are slender, hya-line, and fragile. The lower portions of these become agglutinatedinto short columnar masses. The free portion of each pedicel isusually about the length of the spore. PROTOIJASIDIOMVCETES 419 XVIII. HOLLYHOCK RUST Piiccinia malvacearum Mont. , W. R. The Hollyhock Rust. Cornell Agl. Exp. Sta. Built. 25 :154-155. Fig. 204. Puccini A malvacearum : Rust of Hollyhock. (Photograph by H. H. Whetzel) The hollyhock rust is known to infest a kirge number of generaand species of the mallow family (Malvaceae). It is at present widelydistributed throughout a large portion of the world, and is in theUnited States most important on the cultivated hollyhock {AltJuca 420 FUNGOUS DISEASES OF PLANTS rosed). The fungus is apparently a native of Chile and was notfound in central Europe until between 1873 and 1877. It wasevidently introduced into the United States prior to 1886 andhas received special attention since about 1890. On the hollyhock the fungus commonly occurs in such quantitythat the proper development and normal functions of the leavesmay be seriously inhibited. The sori are most abundant on theunder surfaces of the leaves (Fig. 204), but they also occur uponother parts. They are at first small and circular in
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