PINE CONE FUNGUS 267 



branches. From these swollen spots abnormal branches, 

 'witches' brooms,' often spring, and are readily recognised 

 at a distance by growing quite erect, and in the much 

 smaller yellowish leaves which fall off about the end of 

 August, the ' witches' broom ' being deciduous. 



Aecidia are only formed on the ' witches' broom ' leaves, 

 and not on the swollen portions of the branch, as in other 

 species. 



The bark is ruptured and thrown off at the cankered 

 swellings, which consequently often serve as a starting- 

 point for wound-parasites, especially Polyporus hartigii 

 and Flammula adiposa. 



Hartig and Somerville, Diseases of Trees (Engl. ed.), 

 p. 17, figs. 



Peridermium cerebrum, Peck. Forms barrel - shaped 

 swellings on the trunk of Pinus ponderosus^ Dougl., in 

 America. 



Peridermium giganteum, Mayr. Also forms barrel- 

 shaped swellings on the trunk of Pinus densiflora^ Sieb. 

 and Zacc., and P. thunbergii, Parl., in Japan. 



Peridermium thomsoni, ^$eik.=Aecidium thomsoni, Berk., 

 Gard. Chron., 1852, p. 627, with fig. Forms large, 

 elongated aecidia on the leaves of Picea morunda, Link., 

 in Sikkim. 



Peridermium orientale, Cooke. Also an Indian species 

 from the neighbourhood of Simla, growing on leaves of 

 Pinus longifolia and P. excelsa. The American forms 

 referred to this species are distinct. 



Several other species of Peridermium are parasitic on 

 the bark or leaves of conifers. 



