May 1905] Notes on the Erysiphaceae of Washington 
107 
8. Phyllactinia corylea Persoon. — On Alnus rubra, 
Cirsium lanceolatum, Cornus canadensis, C. nuttallii, C. pubes- 
cens, C. stolonifera, Crataegus douglasii, C. piperi, Dipsacus syl- 
vestris, Epilobium adenocaulon, Erigeron concinnus, Fragaria 
bracteata, Holodiscus discolor, Lactuca scariola, Mentha viridis, 
Philadelphus lewisii, Plantago major, Prunus demissa, Pyrus 
baccata, P. rivularis, Rhus toxicodendron, Ribes divaricatum, 
Rosa gymnocarpa, R. pisocarpa, Rumex occidentalis, Salix cor- 
data, S. rostrata, Solidago serotina, Taraxacum officinale, and 
Viola nuttallii. 
A very common species. There is a marked difference in 
the diameter of the perithecia on some hosts; perithecia on Cornus 
nuttallii measure 150-200 mmm., on Crataegus douglasii 160-180 
mmm., on Pyrus rivularia 180-215 mmm., on Ribes divaricatum 
235-270 mmm.; on many of the other hosts there is not so marked 
a variation. 
9. Podosphaera oxyacanthae DC.— A rare species on 
Prunus cerasus, Pyrus baccata, Spiraea corymbosa and Symphor- 
icarpus racemosus. 
10. Podosphaera oxycanthae var. tridactyla Wallr.— 
On Prunus emarginata, P. persica and Spiraea douglasii. En¬ 
demic to the Puget Sound region in vicinity of Seattle. 
One perithecium measuring about 100 mmm. in diameter 
contained two.asci. Each ascus measured 64x64 mmm., globose 
but somewhat depressed on one side near the base. Each con¬ 
tained eight spores of normal size and shape. 
11. Sphaerotheca mors-uvae Schweinitz.— A rather 
common species growing on the cultivated gooseberry in eastern 
Washington. 
12. Sphaerotheca humuli DC.— On Arnica pedunculata, 
Bidens frondosa, Geranium incisum, Geum macrophyllum, G. 
strictum, Gilia gracilis, G. heterophylla, G. linearis, G. microste- 
ris, Lophanthus urticifolius, Mentha canadensis. Polemonium 
micranthum, Potentilla convallaria, P. gracilis, Rubus nutkanus, 
R. spectabilis, Troximon nuttallii and Vicia sp. 
13. Sphaerotheca humili var. fuliginea Schlecht.—On 
Brunella vulgaris, Castilleia miniata, Gaillardia aristata, Geranium 
incisum, Lophanthus urticifolius, Matricaria discoidea, and Mi- 
crosteris troximoides. 
There is little ground on which to separate the variety from 
the species. The perithecia of the variety on the average are 
smaller and the difference in the size of the cells in the outer wall 
is fairly constant. Cells in the outer wall of perithecia on Mentha 
canadensis vary in diameter from 12-45 mmm., averaging about 
15 mmm. The larger irregular cells had faint walls or lines 
representing lost cell walls. Perithecia on a leaf of Lophanthus 
urticifolius had quite regular cells varying from 8-20 mmm.; on 
