THE RUbTS OF NOVA SCOTIA. — FKASER, 391 



The name Roestelia has been applied to the aecial stage of 

 ihe Gymnosporangium rusts. Usually the peridium dehisces 

 by longitudinal slits, and thus soon becomes fimbriate and 

 revolute. Some species have their aecial stage on the apple 

 and often cause serious damage, l^o uredinial stage is known. 

 This is remarkable as all other heteroecious rusts possess all 

 the spore forms. 



The genus is characterized by the teliospores having long 

 hyaline pedicels which swell in moisture and form a jelly-like 

 matrix in which the spores are embedded. This yellowish, 

 jelly-like material is often very conspicuous during wet 

 i\^eather in spring and early summer. The telial mycelium is 

 perennial, the teliospores being produced in spring and germin- 

 ating immediately. The aecial stage develops slowly but dies 

 during the summer. In many species the perennial mycelium 

 produces distortions on the branches which are sometimes 

 globular in shape. This has given the fungus the name of the 

 ■^'Cedar Apple Fungus." 



GYMNOSPORANGIUM Sp. 



A roestelia on the fruit of Amelanchier was collected at 

 Walton, Lunenlnirg Co., by Miss Clara A. Corkum. (I am 

 indebted to Prof. H. W. Smith of Truro for the specimens). 

 It is doubtless the aecial stage of one of the species of 

 Gymnosporangiuni, probably either G. clavariae forme (Jacq.) 

 D.: G. or G. germinale (Schw.) Kern {G. clavipes C. & P.). 

 Both of these species may have their aecial stage on the fruit 

 of Amelanchier and the telial stage on Juniperus nana Willd. 



MacKay (Trans. K S. Inst. Science 11:141, 1904) 

 records Roestelia lacerata on the authority of Dr. John Somers 

 and Prof. G. Lawson. This is the aecial stage of G. clavariae- 

 forme. It is widely distributed in North America. 



MacKay also records on the authority of Prof. G. Lawson 

 G. jiiniperi Link, from Halifax Co., but gives no host. It may 

 ibe, as the Roestelia and Gym,nosporangiU7n were collected at 



