Studies in the genus Gymnosporangium 



♦ 



Frank D. Kern 



The first systematic study of the genus Gymnosporangium as 

 it occurs in America was published by Farlow in 1880 in a paper 

 entitled " The Gymnosporangia or Cedar-Apples of the United 

 States."f European investigators had demonstrated several years 

 earlier % the genetic connection between members of the genera 

 Gymnosporangium and Roestelia, and it was the desire to study 

 the development of the American species in a similar manner 

 which led to this attempt to define the species morphologically. 

 Such a course was especially necessary because of the variety of 

 forms inhabitating the same host, and the consequent small 

 amount of aid which the host furnished in defining the limits of 

 the various forms or species as they were believed to be. For 

 ^stance, the earlier artificial cultures in America showed that 

 ^fection on Amelanchier leaves was obtained from the sowing of 

 spores of six apparently distinct species of Gymnosporangium, 

 four of which occurred on the red cedar, Sabina virginiana. The 

 necessity of following up these cultures and determining whether 

 u niform and recognizable differences were evident in the resulting 

 roestelial forms became at once apparent. 



For eleven years, or until 1891, work on this group, by 

 m eans of anatomical studies supplemented with cultures, was 

 k ept up by Farlow and Thaxter. During this period six species 

 of Gymnosporangium were successfully connected to their roes- 

 tel ial phase, only one being a repetition of European investigations. 

 The more important results are contained in the following papers : 

 '' Notes on some Species of Gymnosporangium and Chrysomyxa 

 Reunited States," by W. G. Farlow ; § " The Devel opment 



Sc . R^Tbdbre Section G of the AmericIn^Assoda t i on for the Advancement of 

 CIen ce, at the Chicago meeting, January 2, 1908. 



t Anniv. Mem. Boston Soc. Nat. Hist. 1880. „ 



F t*ot. Zeit. a 3: 291. 1865; 25: 222. 1867. Overs. Danske Vid. Selsk. 

 «6fi l866 : ^S- 1 ^- PL S, 4- 1866. Bull. Soc. Roy. Dan. Sci. 1866: 15, i°- 



Sfroc. Amer. Acad. 20 : 311-328. 1885. 



499 



