RUST FUNGI 



209 



CACE^) while the three-, four or five-celled teliospores are found 

 on CuPRESSiNEiE (ChamcBcy parts, Cupressus, Juniperus, Libocedrus). 

 One autcecious species is G. bermudianum which produces both its 

 aecia and teliaon junipers (7. bermudianum). Kern gives thirty-two 

 species as the number for North America and in vol. 7, North American 

 Flora, part 3, pages 188-190, gives a useful key for the identification 

 of the species. 



Gymnosporangium botryapites causes fusiform swellings on the white 

 cedar, Chamcecyparis tkyoides, on which swellings the two- to four- 



FiG. 79. — Cedar rust on apple, roestelia stage with pustules. (After Jones and 

 Bartholomew, Bull. 257, Agric. Exper. Stat., Univ. Wise, July, 1915.) 



celled teliospores are formed. The aecia occur on two species of shad 

 bush: Amelanchier canadensis and A. intermedia (Fig. 73). 



In Gymnosporangium nidus-avis, the telia arise from a perennial 

 myceUum which often dwarfs the young shoots and causes bird's-nest 

 distortions in which usually there is a reversion of the leaves to the 

 juvenile form, sometimes "causing gradual enlargements in isolated 

 areas on the larger branches of Juniperus virginiana with aecia on 

 several species of Amelanchier (Fig. 73). 



Juniperus communis is the host of the telial stage of G. clavarimforme, 

 which appears on long fusiform swellings of various-sized branches, 

 14 



