Classification, 1 1 1 



Fliytoplitliora infestans, De Bary (figs. 121 — 126). 



.Mycelium slender, liaustoria very rare ; gonidio- 

 phores slender, attenuated upwards, furnished above 

 with a few slender, tapering, simple or rarely divided 

 branches; branches with scattered, swollenportions cor- 

 responding to the points of origin of gonidia ; gonidia 

 elliptical, colourless, with a prominent papilla at the 

 apex, 25-30x15-20 /u, ; sexual condition unknown. 



PhytojjJithora infestans, De Bary, Journ. Agric. 

 Soc. ser. ii. vol. xii. 1876; Sacc. Syll. vii. 802. 



Feronosporcb infestans, De Bary, Ann. Sci. Nat. ser. 

 iv. vol. XX. p. 101; Cke. Hdbk. n. 1774; Cke. 

 Micr. Fung. t. 14, f. 264. 



On leaves of the potato, Solanum tuberosum. Very 

 common. 



Causing the well-known potato disease. The 

 gonidiophores emerge from every above-ground part, 

 but more especially from the under surface of the 

 leaves, forming a white downy film. The mycelium 

 is perennial in the tubers. Occurs also on other 

 species of Solanum. 



Plasmopara, Schroet. 



Mycelium thick, furnished with simple globose or 

 ovate haustoria; gonidiophores erect, sparingly 

 branched; gonidia generally papillate; oospores 

 globose, epispore thin, smooth, brownish. 



Flasmopara, Schroet. Krypt. Fl. Schles. Pilze, 

 p. 236; Sacc. Syll. vii. p. 239. 



Peronospora of various authors. 



The species form white films on living leaves and 

 other parts of plants, included under the popular 



