201 



GENUS 222. PERONOSPORA.* Cda. 

 Parasitic threads mostly inarticulate ; spores of two kinds, first 

 on the tips of the branches ; second large, globose, on the creeping 

 mycelium. 

 1. — Peronospora parasitica Cda. on cruciferous plants, Eudlow. 



2. — P infestans Oxsp on potatoes, producing the dreaded 



potato disease 



3. — P ganglioniformis B. on lettuces, Elmhurst. 



4. — P vicice B. on peas, Elmhurst. 



5. — P urticoj Casp on nettles, Elmhurst. 



9. — P — macrospora Uxger on umbelliferae, Elmhurst. 



GENUS 223. VERTlCILLIUM.t Lk. 



Flocci septate, hyaline or coloured ; branches verticillate ; 

 spores apical. 

 1. — Vcrticiliium apicale B.and Br. on fallen oak branches. Ann. 



Nat. Hist., Ser. II. vii. 101, No. 531 icon, Langley, Wilts, 



and Batheaston. 

 2. — V epimyces B. and Br. 1. c. II. vii. 102, on 



Elaphomyces, Bo wood, Wilts. 



GENUS 224. HAPLARIA.t Lk. 



Flocci simple or forked, jointed ; spores scattered over the tips 

 of the threads. 



GENUS 225. POLYACTIS.§ Lk. 



Flocci septate, brownish, branched above ; spores hyaline, in 

 terminal clusters. 



1. — Polyactis cinerea ^t/i-. Botrytis cinerea Eng. Fl. On decaying 

 herbs, very common. 



* From perone, a buckle or brooch (?) and sporos seed. 



t From verticillum, a whorl. 



% From aploos simple. 



S From polus many, and aktia, a spoke of a wheel. 



