ANCYLISTACEAE— PERONOSPORACEAE 



39 



2. Sporangia ellipsoid to piriform, broader than 

 the segments; zoospores encysting at the 

 pore 

 B. Hyphae differentiated into stout trunk and slen- 

 der branches, the latter usually somewhat con- 

 stricted, rarely lacking 



1. Trunk more or less cylindric, the branches 



similar but narrow 



a. Trunk about twice as wide as branches; 



sporangia all alike, smooth; oogones piri- 

 form 



b. Trunk several times wider than branches; 



sporangia of two kinds, smooth and spinose; 

 oogones globose 



2. Trunk not cylindric 



a. Trunk more or less lobed, branches filamen- 



tous, numerous, bearing the reproductive 

 cells 



b. Trunk broadly clavate, hardly branched; re- 



productive cells on short pedicels 



Apodachlya S 102, F 173; 3 



Sapromyces S 163, F 175 



Araeospora 14:454; F 177 



Rhipidium 7:268; S 103, F 180; 

 3 



Mindeniella F 180 



Family 9. ANCYLISTACEAE 

 Schroeter 134; Fitzpatrick 117; Minden 426 



Mycelium mostly poorly developed and scarcely distinct from the fruit-body, the 

 latter tubular, when mature divided into vegetative cells, sporangia or oogones and 

 antherids; entire contents of antherid passing into oogone, oospore lying free; 

 sporangia always producing zoospores. 



A. Hyphae ramose 



1. Vegetative cells present, growing by germ- 



tubes; sporangia lacking 



2. Vegetative cells lacking; sporangia present 



Ancylistes 7:280; S 92, F 124; 3 

 Lagenidium 7:278; S 90, F 122; 

 3 



B. Hyphae simple 



1. Zoospores escaping normally and encysting at 



the pore 



2. Sporangia extruding a vesicle bearing zoospores Myzocytium 7:279; S 90, F 120; 



3 



Achlyogeton 7:277; S 89, F 119 



Family 10. PERONOSPORACEAE 



Schroeter 110; Fitzpatrick 185 



Mycelium abundant, filamentous, 1-celled, much branched, typically endophytic; 

 propagation by means of conidia (sporangia) borne on the ends of conidiophores, 

 producing zoospores or a germinating tube, occasionally by means of normal 

 sporangia; reproduction regularly by means of internal oogones and antherids, 

 borne on the ends of lateral branches; oospores solitary, producing zoospores or 

 a germinating tube. 



Key to Subfamilies 



A. Conidia catenate; conidiophores clavate, simple, 



forming a sorus Albuginae 



B. Conidia or sporangia not catenate; conidiophores 



regularly branched, not forming a sorus 



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