May, 1910.] 
The Ohio Powdery Mildews. 
1 7 1 
Uncinula cicrinata C. & P. Perithecia scattered, somewhat 
lenticular, 160-225 y diameter; cells obscure, 10-14 y; 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 y ; spores 8, 18 x 20-22 x 14 y. 
Host plants in Ohio Herbarium: Acer saccharum, Acer rubrum, 
Acer saccharinum, Cuyahoga Co., E. Claassen; Acer dasycarpum, Colum- 
bus, C. M. Weed. 
Otherwise reported in Ohio: Acer rubrum, Fairfield Co., A. D. Selby; 
Acer saccharum, Columbus, C. M. Weed. 
Podosphaera Kunze. 
Key to the Ohio Species. 
1 . Appendages clear, except at base ; branches of apex not swollen .... 
binncinata 
Appendages dark-brown for more than half their length; branches 
or apex swollen oxyacanthae 
Podosphaera biuncinata, C. & P. Perithecia subglobose, 
55-72 y 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 y, spores 8, 20 x 11—24 x 13 y. 
Host plants in Ohio Herbarium: Hamamelis virginiana, Summit Co., 
Cuyahoga Co., E. Claassen. 
Podosphaera oxyacanthae (DC) DeB. Perithecia subglo- 
bose, 64-90 y in diameter; cells 10-18 y wide; appendages usually 
equatorial, sometimes nearer apex, 4-30 in number, )/£-6 times 
diameter of perithecium, septate, brown for more than half their 
length, apex 2-4 times dichotomouslv branched, branches short, 
tips of ultimate branchlets swollen; ascus 58 x 45-90 x 75 y; 
spores 18 x 10-30 x 17 y. 
Host plants in Ohio Herbarium: Cherry (cult) Ottawa Co., W. A. 
Kellerman ; Prunus virginiana, Cedar Point, E. Claassen ; Spiraea tomentosa, 
Fairfield Co., W. A. Kellerman; Prunus cerasus, Columbus, 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. . . .euphorbiae 
Appendages not so 2 
2. Ultimate branchlets usually recurved 3 
Ultimate branchlets not recurved 4 
3. Appendages long and flaccid, apex much branched, ornate and close 
alni, var. extensa 
Appendages short, not flaccid, ultimate branchlets all distinctly 
recurved alni 
Appendages 24-8 times diameter of perithecium, apex moderately 
branched, widely forked alni. var. vaccinii 
