420 FUNGOUS DISEASES OF PLANTS 



rosea}. The fungus is apparently a native of Chile and was not 

 found in central Europe until between 1873 and 1877. It was 

 evidently introduced into the United States prior to 1886 and 

 has received special attention since about 1890. 



On the hollyhock the fungus commonly occurs in such quantity 

 that the proper development and normal functions of the leaves 

 may be seriously inhibited. The sori are most abundant on the 

 under surfaces of the leaves (Fig. 204), but they also occur upon 

 other parts. They are at first small and circular in outline, but 

 may become confluent over considerable areas. 



During favorable conditions the teleutospores germinate im- 

 mediately, and there is no evidence that the mycelium is gener- 

 ally perennial. Nevertheless, Fischer believes that in temperate 

 climates the wintering over is ordinarily effected by means of 

 teleutospores which fail to germinate on account of being over- 

 taken by unfavorable conditions. The spores are light colored 

 and measure I7-24X 3 5-63 ft. They are often spindle-shaped, 

 and the pedicel is long, frequently from 100 to 130/4. 



This disease has been fairly well controlled by the destruction 

 of diseased portions of plants and by spraying with Bordeaux 

 mixture. 



XIX. PUCCINIA: OTHER SPECIES 



Puccinia Helianthi Schw. This euautouredo occurs commonly 

 upon numerous species of Helianthus, including the sunflower 

 (Helianthus annuus}. Recent experiments indicate that the form 

 on Helianthus tuberosus is at least physiologically distinct, and 

 doubtless the species may be broken up into many forms. Puc- 

 cinia Helianthi (with all spore stages) is distinguished from Puc- 

 cinia Tanaceti, a related but apparently imperfectly known species, 

 by the smooth apex of the teleutospore and the presence of only 

 two germ pores in the uredospores. 



Puccinia coronata Cda. This species has an aecidial stage upon 

 the buckthorn (Rhamnus). At maturity the groups of cluster cups 

 are very conspicuous by the color and also by the deformities. The 

 aecidiospores measure 18-25 x 14-19^. The uredo and teleuto 

 stages are common upon oats, and on such cultivated grasses as 

 Dactylis glomerata and Festuca sylvatica. The uredosori are 



