408 GEOGRAPHICAL DISTRIBUTION OF FUNGI 



TABLE 30 



Latitudinal Zonation of North American Rust Genera 



Boreal Temperate Tropical 



Total 202 604 411 



The list of rusts introduced into North America, in the account 

 by Arthur (1929), contains such important species as Cronartium 

 ribicola, Uromyces appendiciilatus phase oil, U. appendiculatus 

 vignae, U. betae, U. caryophyllinus, U. trifolii, Puccinia arachidis, 

 P. asparagi, P. chrysanthemi, P. glumarwn, P. malvacearum, P. 

 rubigo-vera secalis, and P. rubigo-vera tritici. 



Cronartium ribicola was first known from collections made in 

 Russia before 1856. In 1861 it was noted in Finland; in 1871, in 

 East Prussia; in 1880, in Sweden; in 1885, in Norway; in 1889, in 

 France; in 1892, in the British Isles; and in 1906, in the United 

 States. 



Puccinia malvacearum is endemic in Chile, where it was first 

 noted in 1852. It did not reach North America until 34 years 

 later. Meantime it spread to Australia in 1857, to Spain in 1869, 

 to France in 1872, to Germany and the British Isles in 1873, to 

 Italy in 1874, to Switzerland in 1875, to Greece in 1877, to Sweden 

 in f887, and to Finland in 1890. 



Distribution of Septobasidium. The symbiotic relationship 

 between Septobasidium and scale insects, clarified by the work of 

 Couch (1938), serves as the most potent factor in accounting for 

 the distribution of members of this genus. If, for example, the 

 symbiotic scale insect is limited to the tropics, then the particular 



