52 
IOWA ACADEMY OP SCIENCE 
Common throughout the summer, causing a more erect habit in the host, but 
not having such a pronounced effect as the aecia of Uromyces EupJiorMae. 
24. Pekonospora Hydrophylli Waite. 
On Hydrophyllum virginicum L. 
A single collection was made June 11, 1908, the infection covering only a few 
leaves and not being abundant on these. 
25. Peronospora parasitica (Pers.) de Bary. 
On Dentaria laciniata Muhl., Draha caroUniana Walt., Erysimum parviflora 
Nutt., and Lepidium apetalum Willd. 
Common and rather abundant, probably infesting a still greater number of 
hosts as it is to be looked for on almost every species of crucifer. 
26. Perinospora Potentillae de Bary 
On Agrimonia mollis (T. & G.) Britton, Geum canadense Jacq. and Potentilla 
monsepalensis L. 
Rather rare through the entire season. 
27. Peronospora sordida Berk. & Br. 
On Scropliularia marylandica L. 
Not common, but where found rather abundant. Spring and early summer. 
28. Peronospora trifoliorum de Bary. 
On Astragalus canadensis L. (A. carolinianus L.) 
Rather abundant in early summer. 
29. Peronospora Viciae (Berk.) de Bary. 
On Yicia americana L. 
Rather frequent during the early summer. 
30. Bremia Lactucae Regel. [Peronospora gangliformis de Bary.] 
On Lactuca canadensis L. 
Neither common nor abundant. Midsummer. 
CLASS ASCOMYCETES. 
ORDER EXOASCALES. 
Family Exoascaceae. 
31. Exoascus Pruni Puckel. 
On Primus amerieana Marsh. 
Not uncommon on wild plums causing the distorted fruits known as plum 
pockets. 
32. Taphria coerulescens (Mont. & Desm.) Schrceter, 
On Quereus rul)ra L., and Q. palustris Moench. 
Abundant in spring and early summer, causing yellowish or somewhat water- 
soaked blisters on the leaves of the oak. 
