May, 1910.] The Ohio Powdery Mildews. 1 7 1 



Uncinula cicrinata C. & P. Perithecia scattered, somewhat 

 lenticular, iG(J-225 ix diameter; cells obscure, 10-14 p.; appendages 

 crowded, very numerous, length a little less than diameter of 

 perithecium, nonseptate, colorless, apex not helicoid; asci 9-26, 

 68 X 29-86 X 40 // ; spores 8, 18 x 20-22 x 14 ;r 



Host plants in Ohio Herbarium: Acer saccharuni, Acer rubrum, 

 Acer saccharinum, Cuyahoga Co., E. Claassen; Acer das3'carpum, Colum- 

 bus, C. M. Weed. 



Otherwise reported in Ohio: Acer rubrum, Fairfield Co., A. D. Selby; 

 Acer saccharum, Columbus, C. M. Weed. 



PODOSPHAERA KunZC. 



Key to the Ohio Species. 



1 . Appendages clear, except at base ; branches of apex not swollen .... 



biuiici}iata 



Appendages dark-brown for inore than half their length; branches 



or apex swollen oxyacanthae 



Podosphaera biuncinata, C. & P. Perithecia subglobose, 



55-72 a in diameter; appendages equatorial, 4-15 in number, 



3-5 times diameter of perithecium, straight, nonseptate, colorless, 



or light brown at base, apex once dichotomously branched, 



branches variable and often recurved; ascus short-stalked, 



45 X 40-50 x 48 ,«; spores 8, 20 x 11-24 x 13 fx. 



Host plants in Ohio Herbarium: Hamamelis virginiana. Summit Co., 

 Cuyahoga Co., E. Claassen. 



Podosphaera oxyacanthae (DC) DeB. Perithecia subglo- 

 bose, 64-90 /( in diameter; cells 10-18 // wide; appendages usuallv 

 equatorial, sometimes nearer apex, 4-30 in number, 3^-6 times 

 diameter of perithecium, septate, brown for more than half their 

 length, apex 2-4 times dichotomously branched, branches short, 

 tips of ultimate branchlets swollen; ascus 58 x 45-90 x 75 jx; 

 spores 18 X 10-30 x 17 ii. 



Host plants in Ohio Herbarium: Cherry (cult) Ottawa Co., W. A. 

 Kellerman ; Pruntis virginiana, Cedar Point, E. Claas.sen ; Spiraea tomentosa, 

 Fairfield Co., W. A. Kellerman ; Prunus cerasus, Columbtis, H. H. Richard- 

 son. 



Otherwise reported in Ohio: Cherry (cult), Columbus, C. M. Weed, 

 F. Detmers, Dayton, Jos. Potts. 



Key to the Ohio Species. 



1. Appendages angularly bent, branches lax and irregular. . . .eiipJiorbiae 

 Appendages not so 2 



2. Ultimate branchlets usually recurved 3 



Ultimate branchlets not recurved 4 



."}. Appendages long and flaccid, apex much branched, ornate and close 



alni, var. cxtensa 

 Appendages short, not flaccid, ultimate branchlets all distinctly 



recurved alni 



Appendages 2^-8 times diameter of perithecium, apex moderately 

 branched, widely forked alni. var. vaccinii 



