196 BOTANICAL GAZETTE [march 



Dietel (11) considered that Uromyces is the most primitive 

 of the Pucciniaceae, both on account of the possession of 1 -celled 

 teliospores, and because it occurs upon such diverse families of 

 monocotyledons and dicotyledons. Whether long cycle or short 



cycle rusts are more primitive is still a mooted question. 



The existence of species of these rusts as lepto-forms or micro- 

 forms, that is, whether or not the teliospores germinate upon 

 maturity, while subject somewhat to seasonal variation, is a fairly 

 constant and characteristic feature with each species. 



Life history ; cytology 



The life cycle is simplified in a short cycle species to the extent 

 that only telia, often with pycnia, are produced. The occasional 

 occurrence of a few urediniospores in the telia is a phenomenon in 

 common with other groups of rusts which ordinarily do not bear 

 such spores. 



Fischer (12) first cultured a short cycle Uromyces. He sowed 

 teliospores of U. Cacaliae (DC.) Unger upon Adenostyles alpina 

 Kern, securing telia again without the intervention of any other 

 spore stages. No trace of pycnia was found. In 1905 Fischer (14) 

 reported the culture of the short cycle species of Uromyces which 

 occurs in Europe as well as in America, U. Solidaginis. He sowed 

 teliospores upon Solidago Virganrea alpestris, and in about 13 days 

 noted the infection upon the leaves; telia were produced, but in no 

 case were pycnia to be observed. While North American material 

 of this species has not been cultured, it is supposed that similar 

 conditions obtain here. Schneider (24) cultured U. Scillarum 

 (Grew) Wint., a short cycle form, and reported specialization as to 

 hosts. The teliospores were found to be capable of germination, 

 either at once or after a period of rest. No cultures of endemic 

 North American short cycle Uromyces seem to have been reported. 

 Carleton (8), Arthur (3), and others, however, have reported 

 cultures of some species of lepto- Puccinia. Wille (27) recently 

 found a sharp specialization of the lepto-form Puccinia Arenariae 

 upon the different host genera attacked. 



The evidence obtained from cultures indicates that similar con- 

 ditions exist in the short cycle forms, both of Uromyces and Puccinia. 



