Wilson : North American Peronosporales 365 



scription of Spegazzini's species shows a close conformity thereto 

 and leaves no doubt as to their identity, although no South 

 American material is at hand for comparison. Judging from the 

 origin of the host, it is not improbable that both host and fungus 

 were introduced into the Southwest at the same time, although 



i 



this is not one of the species recorded by Spegazzini as a host of 



Peronospora Nicotianae. 



Inasmuch as the description of the species is rather inaccessible 



it is not unfitting to append a brief characterization : 



Hypophyllous, forming brownish discolorations on the leaves ; 

 conidiophores erect, 250-500 ft x 10-12//, 6 or 7 times dichoto- 

 mously branched, ultimate branchlets 15-18/i x 2-^jx, divaricate, 

 acute; conidia ellipsoid or ovoid, 18-20// x 9-1 1 /A very light 

 violet; oogones globose, angled, hyaline, 80-100//; oospores 

 50-80//, globose; epispore subopaque, closely reticulate, the 

 areolae slightly elongate. 



New York Botanical Gari.kn. 



