THE FUNGI WHICH CAUSE PLANT DISEASE 545 



G. allescheri Bres. and G. nanoti P. & D. occur on 

 Palms. 



G. tiliae Oud. is a serious parasite on the twigs, petioles and leaves 

 on the linden in Denmark. 



G. tiliaceum (AU.)^^* said to be distinct from the above occurs 

 in Germany on Tilia. 



G. juglandis (Lib.) Mont, causes a common, and serious leaf 

 blight of the butternut."* 



G. fagi (D. & R.) West is on Fagus; 



Spots subcircular, fuscous above, olivaceous, vitreous be- 

 neath; acervuli small, prominent, honey-colored; conidia oblong 

 ovate, 15-20 x 7-8 m, minutelj' 1 to 3-guttulate; conidiophores 

 fasciculate, cylindric, fuscous. 



G. apocryptum E. & E. causes a nursery disease of maples 

 and of box elder. ^™ 



Acervuli numerous, minute, mostly hypophyllous, on dead areas 

 of the leaf; conidia very variable in size, 5-12 x 2J4-5 n, oblong 

 to narrowly elliptic. 



G. betularum E. & M. 



Spots rounded, 2-3 mm., blackish margined; acervuli amphig- 

 enoas, brownish, 120-140 n, becoming cupulate; conidia hyaline, 

 obovate, 9-10 x 5-6 ix. 



It is common on leaves of American birches. 



Other common species on deciduous trees are: 



G. tremulae (Lib.) Pass, on Populus; 



G. betulinum West, on beech; 



G. alneum West, on alder; 



G.'carpini (Lib.) Desm. on Carpinus; 



G. coryli (Desm) Sacc. on Corylus; 



G. quercinum West, on oak; 



G. nervicolum Massal on oak. 



G. kawakamii Miy. is found on Paulownia in Japan causing 

 witches' brooms. 



G. saccharini E. & E. 



Acervuli minute, numerous; spores oblong-fusoid, 6-7 x 1.5-3 /i, 

 hyaline, continuous. On maple. 



G. caryse E. & D. =Gnomonia caryae.*^' 



Spots suborbicular, 1-2 cm., margin subdefinite; acervuli 



