158 



ASCOMYCETES. 



contain only conidia, whereas those on Alnus-incana are said 

 by Sadebeck to contain only ascospores, unless on very rare 

 occasions. In the lower and higher Alps, although both species 

 of alder are not infrequently found together, yet the Exoascus 

 is found only on Alnus incana, and no species occurs on A. 

 glutinosa. 



FIG. 53. .coascus alni-incanae in catkins of Alnus incana. Many of the scales 

 are developed as elongated red soft tongue-like structures, on which the asci^are 

 produced as a whitish coating, (v. Tubeuf phot.) 



Exoascus epiphyllus Sad. (E.-. borcalis Joh. 1 ) The witches'- 

 broom fungus of the white alder (Alnus incana.) 



The author 2 was the first to describe and figure this form 

 of disease in 1884; and Sadebeck recently succeeded in pro- 



1 A'. ,SVen. Vet. Akad. 1885 and 1887. Tubeuf, Botan. Central^., 1890. 



2 Tubeuf , Beitriirje, z. Kenntniss d. BaumTcrankheiten, 1888. 



