TWENTY-THIBD ANNUAL MEETING. 13o 



On Lepidium intennediurn Gv. 

 1987, on leaves, April 4, 1890, Manhattan; 1988, on leaves, April 28, 1890, Man- 

 hattan; 1989, on leaves, May 8, 1890, Manhattan. 



24. Peronospora alta Fuckel. 



On Plantago Rugelii Decaisne. 

 1972, coll. M. Varney, May 26, 1890, Manhattan; 1973, June 1, 1890, Manhattan; 

 1974, with mature oospores, OCTOBER 25, 1890, Manhattan. 



25. Peronospora Candida Fuckel. 



On Audrosace occidentalis Ph. 

 1979, with abundant mature oospores, April 6, 1890, Manhattan. 



26. Peronospora grisea Unger. 



On Veronica peregrina L. 

 1984, with mature OOSPORES, June 1, 1890, Manhattan. 



28. Peronospora Swinglei Ellis & Kellerman. 



On Salvia lanceolata Willd. 

 1976, on leaves and stems, JULY 3, 1887, Manhattan. 



29. Peronospora effusa (Greville) Rabenhorst. 



On Chenopodiuni album L., var. viride. 

 1982, APRIL 27, 1890, Pottawatomie county, northwest of St. George; 1983, coll. 

 M. Varney, May 26, 1890, Manhattan. ^_ 



30. Peronospora Rumicis Corda. 



On Polygonum dumetorum L., var. scandens Gray. 



1991, with mature OOSPORES, on leaves, JUNE 1, 1890, Manhattan; 1990, coll. M. 

 Varney and W. T. Swingle, with mature oospores, on leaves, June 2, 1890, Man- 

 hattan. 



This rather rare species was found this year in considerable quantity on plants 

 growing in shady woods, on the old site of a creek-bed. The oospores were quite 

 abundant in the oldest yellow or brown leaves, but could not be found on the bright 

 green leaves bearing conidiaphores. The oospores are 30 to 40 y« diam., with a brown 

 epispore which is very irregularly ridged or folded, giving the oospores a star-like 

 appearance in optical section. The oogonia are shriveled and difficult to see clearly. 

 The epispore varies in thickness from 2 to 10 ,u. 



31. Peronospora Euphorbiae Fuckel. 



On Euphorbia glyptosperma Engelm. 



1994, coll. W. T. Allen, with mature oospores, on leaves, August 5, 1890, Man- 

 hattan. 



Prof. Byron D. Halsted says ^ "Peronospora Euphorbiae, Fckl., is a species which 

 quickly disappears in times of drought."' This summer has been a very dry one, 

 and during a very dry time Peronospora Euphorbiae was collected in quantity on 

 Euphorbia glyptosperma growing on some dry, sandy hills. At the same time a very 

 little Cystopus Portulacae was observed on Portulaca obracea growing in a neighbor- 

 ing corn-field. Aside from these two species the Peronosporaceae had disappeared, 



• Halstead, Byron D., 'Downy Mildews in a Dry Season, in Bull, from the Botanical Department 

 of the State Agricultural College, Ames, Iowa, February, 1888, p.98; Peronosporeae and Rainfall, in 

 Journal of Mycology, vol. 5, No. 1, March, 1889, p. 9. 



