PERONOSPORACEAE 17 



cells, sporangia or sex cells; sporangia producing zoospores; vegetative cells pro- 

 ducing a long tube, which penetrates new host-cells ; oospores globose or elliptic. 



I. Sporangia lacking, vegetative and sex cells alone formed 



Ancylistes 7: 280, S. 92 



II. Sporangia also present Resticularia 9: 348, S. 92 



Family 12. PERONOSPORACEAE 



Schroeter i io, 7: 233, 9: 340, u : 242, 14: 457, 16: 396, 17: 5*9 

 Mycelium abundant, filamentous, much branched, one-celled, endophytic ; propaga- 

 tion by conidia borne on the ends of conidiophores, conidia producing zoospores or 

 a germinating tube ; sexual reproduction by means of endophytic antherids and 

 oogones, borne on the ends of lateral branches; oospores single, globose, producing 

 zoospores or a germinating tube. 



Key to the Subfamilies 



I. Conidia in chains, conidiophores club-shaped 



Albuginae 



II. Conidia single, conidiophores branched Peronosporae 



Subfamily Albuginae 

 Mycelium intercellular, haustoria globose ; conidiophores densely grouped into a 

 conidial layer beneath the epidermis ; conidia globose, ellipsoid or subcylindric, in 

 chains on the ends of the conidiophores, usually producing zoospores, rarely a germinat- 

 ing tube ; oospores globose, producing zoospores. 

 A single genus Albugo 7: 233, S. no 



Subfamily Peronosporae 



Mycelium intercellular, rarely intracellular, haustoria of various form; conidio- 

 phores thread-like, above the epidermis, branched, without cross-walls ; conidia single 

 on the tips of the branchlets, producing zoospores or a germinating tube; oospores 

 globose, with a well-developed outer wall, germinating by means of a tube. 



I. Conidiophores slender, with long and slender branches 



1. Conidiophore growing after the formation of the first conidia, producing new 



joints Phytophthora 7: 237, S. 113 



2. Conidiophore not growing and making new extensions 



a. Conidia papillate at the tip 



(1) Conidia on stalks arising from irregular disks 



Bremia 7: 243, S. 116 



(2) Conidia on stalks arising directly from the unchanged ends of the conidi- 



ophores Plasmopara 7: 239 



b. Conidia not papillate at the tip Peronospora 7: 244, S. 117 



II. Conidiophores stout, swollen at the tip, or with short thick branches 



1. Conidiophore simple up to the enlarged tip, which bears the conidia on slender 



stalks Basidiophora S. 114 



2. Conidiophore with short thick branches bearing the conidia on flask-like stalks 



Sclerospora 7: 238, S. 114 



