1036 AQUATIC PHYCOMYCETES 



Wall of oogonium smooth 

 Oospore plerotic 



Catenulate spherical asexual reproductive bodies present, 

 terminal or intercalary, single, or three to eight in series, 

 10-20 y. (av. 15 jjl) in diameter, producing one to three 

 germ tubes; sporangium with irregularly swollen budlike 

 outgrowths in simple or complex aggregations; zoo- 

 spores 8-11 by 6 ;jl; oogonium smooth-walled, 18-38 y. in 

 diameter, terminal or intercalary; antheridia monocli- 

 nous or diclinous, one to twelve (usually five to six) to an 

 oogonium, clavate, crooknecked, making narrow apical 

 contact with oogonium; oospore with a smooth, thick 

 wall, 16-32 [i in diameter . . P. catemdatum Matthews, p. 40m 

 Catenulate bodies absent 



Antheridia monoclinous, usually one, arising mostly from 

 the oogonial stalk, borne on a short, rarely branched 

 stalk, antheridial cell allantoid-clavate, the apex con- 

 tacting the oogonial wall; oogonia 12-19 a (mostly 17- 

 18 y) in diameter; oospore with a moderately thin 

 wall; sporangium with a few to numerous, irregularly 

 branched, inflated toruloid elements forming simple or 

 involved complexes; zoospores 7-8 \x in diameter when 

 encysted; in water culture with mosses 



P. torulosum Coker and Patterson, 1 p. 41m 

 Antheridia diclinous, not proximal to oogonium in origin, 

 antheridial cells arising from separate simple branches, 

 one to two on each of the rarely formed 1 8-26 y. in 

 diameter oogonia; oospore with a thick wall; spo- 

 rangium with irregular to spherical toruloid outgrowths 

 8-20 \j. in diameter; zoospores not observed; in vege- 

 table debris in algal culture. . . P. inflation Matthews, p. 46m 

 Oospore aplerotic 



Antheridia borne on branched stalks which often wind around 

 the oogonial stalk, one to six, monoclinous (androgynous) 

 or diclinous; oogonium spherical, 21-35 ;j. in diameter; 

 oospore 18-28 u. in diameter, wall 1.2-3.3 y. thick; lobes 

 of sporangial apparatus moderately broad, not com- 

 plicate; zoospores 10-1 1 by 7.5 y.; on rice bait in water 



P. helicum T. Ito 2 

 Antheridia not on branched or coiled stalks, one or several, 

 monoclinous; oogonia 21.6-27 u in diameter; oospore 



1 P. graminicolum var. stagni Hohnk (1953a) in saline habitats seems to belong here. 



2 J. Jap. Bot., 20: 56, fig. 1. 1944. 



