The Peronospore.^ of Iowa. 51 



. dew" was not plentiful, but where it had obtained a 

 foothold, the host plant was dwarfed and entirely 

 covered with the fungus to the ground. 



25. Cystopus candidus. — L. 



On Sisvmhrmm officinale, S. canescens, Capsella bursa- 

 paston's, JSfasturtitim -pahtstre, N. sessilijlormn, Lep- 

 idium virginicmn, Brassica nigra. Ames, Iowa 

 City. 



26. C. cuBicus. — Lev. 



On Ambrosia arteniisiae folia. Ames, Iowa City, (Mc- 

 Bride). 



27. C. BLiTi. — Lev. 



On Aniarantus retroflexus., A. bhtoides, A. albns, Acnida 

 tamariscina. Ames. 



28. C. PORTULACAE. Lcv. 



On Portnlaca oleracca. Common. 

 Peronospora — sp. 



On Hydrophylhun virginicuni. Decorah, Iowa City, 

 Ames, (Halsted). 



This was first reported byMr.Holway last spring (1888) . 

 About the same time that I received a specimen from 

 him, I found it at Iowa City. The next day it was 

 discovered b}-- Dr. Halsted at Ames. Thus it ap- 

 peared almost simultaneously in three widely separa- 

 ted districts. The species is in the hands of Dr. Far- 

 low at present. 



On Phlox divaricata. Decorah. 



Index of Host plants. 

 Ranunculace^ — P. pygmcBU, P. ficarice. 

 Cruciferae — P. parasitica, C. candidus. 

 Caryophyllace^ — P. alisnearum. 

 PoRTULACACE^ — C. portulac(£. 

 Geraniace^ — P. obducens, P. geranii. 

 ViTACE^ — p. viticola. 



