PEAR LEAF CLUSTER-CUPS 257 



the branch might extend and produce fruit beyond the 

 portion treated. 



The preventive treatment for arresting the ravages of the 

 species of Gymnosporangium described hereafter is identical 

 with that given above, some species of juniper being in 

 every instance one of the two host-plants upon which the 

 fungus lives and produces its teleutospores. 



Plowright, Brit. Ured. and Ustilag., p. 233. 



PEAR LEAF CLUSTER-CUPS 



(Gymnosporangium sabinae, Winter.) 



The teleutospore condition of this fungus grows onfuni- 

 perus communis,J. oxycedrus,J. virginiana, andy. phoenicea. 

 The gelatinous masses of spores are formed in the spring, 

 and are flattened and about half an inch in length, blackish 

 at first, then reddish-brown. So far as at present known, 

 the aecidium stage grows only on living pear leaves. The 

 aecidiospores in turn germinate on young leaves of the 

 juniper, from whence the mycelium passes into the branch, 

 where it forms a perennial mycelium, from which a crop of 

 teleutospores is produced every spring. 



Plowright, Brit. Ured. and Ustilag., p. 230. 

 Prillieux, Malad. des Plantes Agric., vol. i. p. 258. 

 Fischer, Zeitschr.f. Pflanzenkr., vol. i. pp. 193 and 283. 



MEDLAR CLUSTER-CUPS 



(Gymnosporangium confusum, Plowr.) 



This fungus closely resembles in general appearance and 

 structure Gymnosporangium sabinae, but differs in its life- 

 history. The secondary spores will not germinate and 



R 



