144 



Mycologia 



brought about an infection, resulting in the uredinia and telia of 

 Cronartium quercum (Brond.) Arth. 



In nature, there is constantly associated with Peridermium 

 harknesii a species of Coleosporium on a number of species of 

 Aster. This association was found so constantly this year, as to 

 venture the prediction that the Coleosporium may be a telial form 

 of this species of Peridermium. It is very evident that the telial 

 form cannot be a Cronartium on oaks, since none are found in 

 an immense region in the Northwest, where this fungus occurs on 

 the pines. It occurs where there are no oaks within a thousand 

 miles. 



Peridermium harknesii, like P. cerebrum, kills many young 

 pines, but is not to be considered as dangerous a species as P. 

 filamentosum in its effects on older trees, because it does not have 

 the ability like the latter to spread along the limbs from the point 

 of infection, but remains confined to the galls it forms. 



3. Peridermium montanum Arth. & Kern 



This species of Peridermium attacks the leaves of Pinus con- 

 torta Loud, in the Northwest, but is not so widely disseminated 

 as P. harknesii. It exerts an injurious effect on the leaves at the 

 time it forms its aecia, owing to the bursting of the epidermis of 

 the leaves by the pustules of the fungus. The leaves lose water, 

 and gradually die, in fact, live but a short time after the aecia 

 mature. This causes a premature shedding of the leaves, so that 

 where a lodgepole pine, if healthy, would bear 5 to 7 years' foliage, 

 trees after being attacked by an epidemic of this Peridermium 

 usually bear only 2 to 3 years' growth of needles, all of which 

 except the youngest, are plainly diseased. 



This fungus was found epidemic this year only in a small area 

 in Gallatin National Forest, near Bozeman. A species of Coleo- 

 sporium was found present in great abundance on the leaves of 

 two species of Aster in immediate proximity to badly infected 

 pines. The Coleosporium is very injurious to the leaves of the 

 asters. From this it is possible that the telial form of Peri- 

 dermium montanum may be a species of Coleosporium on Aster. 

 A further study will be made of both species of rust. 



