38 



VAUCHERIALES 



Family 8. SAPROLEGNIACEAE 

 Schroeter 93; Fitzpatrick 146; Minden 506 



Mycelium strongly developed, broadly filamentous, more or less ramose, often 

 constricted; propagation by sporangia producing zoospores or aplanospores; repro- 

 duction by means of antherids and oogones, their contents fusing by means of a 

 connecting tube. 



Key to Subfamilies 



A. Hyphal filaments uniform, not constricted Saprolegniae 



B. Hyphal filaments or their branches constricted 



more or less regularly Leptomitae 



Subfamily Saprolegniae 



A. Zoospores escaping before germination 



1. Sporangia cylindric-clavate to ovoid, zoospores 

 in several rows 

 a. Zoospores escaping through a terminal pore 

 (1) Zoospores scattering upon escape 



(a) Sporangia ovoid; oogones usually 1- 



spored 



(b) Sporangia clavoid; oogones mostly x- 



spored 



(2) Zoospores remaining massed about the 

 pore 

 b. Zoospores not escaping through a common 

 pore 



(1) Each zoospore escaping singly through its 



own lateral pore 



(2) Zoospores freed by the disintegration of 



the whole sporangium 

 2. Sporangia linear and zoospores l-rowed, at 

 least above 



a. Zoospores escaping through a terminal pore 



(1) Sporangia irregular and complex with in- 



flated ramose base with zoospores in 

 several series and filamentous apical 

 portion with a single series 



(2) Sporangia not ramose and inflated 



(a) Zoospores scattering upon escape 



(b) Zoospores remaining massed about the 



pore 



b. Zoospores non-motile, escaping by disinte- 



gration of the sporangium 

 B. Zoospores non-motile, germinating in the spo- 

 rangium 



Subfamily Leptomitae 

 A. Hyphae uniformly cylindric, without trunk and 

 branches, regularly constricted 

 1. Sporangia cylindric, resembling the segments; 



Pythiopsis S 97, F 165; 3 



Saprolegnia 7:268; S 97, F 167; 

 3 



Achlya 7:274; S 99, F 167 



Dictyuchus 7:273; S 99, F 162; 3 

 Thraustotheca S 100; F 160 



Plectospira F 167 



Leptolegnia S 100, F 170; 3 



Aphanomyces 7:276; S 100, 

 F 167; 3 



Geolegnia F 164 



Aplanes S 101, F 158; 3 



zoospores escaping singly 



Leptomitus 7:265; S 101, F 173; 

 3 



