Key to the Genera 



PHYCOMYCETES 



Order 1. PROTOCOCCALES 



Typically 1-celled yellow-green algae, propagating by fission and frequently also 

 by the formation of zoospores; sexual reproduction usually lacking; three fungous 

 families. 



Key to Families 



A. Mycelium lacking 



1. Cells typically amoeboid Plasmodiophoraceae p. 30 



2. Cells not amoeboid 



a. Sporangia separate or grouped, but without a 



soral membrane Olpidiaceae p. 30 



b. Sporangia typically enclosed in a soral mem- 



brane Synchytriaceae p. 31 



B. Mycelium present, hyphae typically few and deli- 



cate Chytridiaceae p. 32 



PLASMODIOPHORACEAE 



Fitzpatrick 48 



Mycelium none; cells consisting of naked more or less amoeboid protoplasts 

 forming single sporangia which produce 1-8 amoeboid or rarely 1-ciliate spores; 

 parasites in plant tissues, frequently causing hypertrophy of the host; closely related 

 to the Mycetozoa and perhaps best regarded as parasitic slime-molds; included here 

 only for convenience. 



A. Spores separate in the host-cells at maturity 



B. Spores remaining united at maturity 



1. Spores united in twos or fours 



2. Spores united in larger numbers 



a. Spores forming a more or less globose hollow 



body 



b. Spore-masses forming 2-layered plates, some- 



times with a small cavity 



c. Spore-mass sponge-like in structure 



Plasmodiophora 7:464, F 55 

 Tetramyxa 7:464, F 59 



Sorosphaera 7:446, F 60 



Sorodiscus F 63 

 Spongospora F 64 



Family 1. OLPIDIACEAE 



Fitzpatrick 71; Minden 227 



Mycelium lacking; cells endobiotic, globose, elliptic or rarely clavoid, typically 

 forming a simple zoosporangium, or a resting sporangium that produces zoospores 

 after a period of rest, or sometimes fragmenting to yield a number of sporangia; 

 zoospores 1- or 2-ciliate 



30 



