PERONOSPORALES 1041 



or intercalary, 14-30 p (av. 24 a) in diameter exclusive of 

 numerous 2-8 \j. long spines; antheridia monoclinous, 

 typically hypogynal, one to four (usually one); sporangia 

 spherical to cylindrical, terminal or intercalary, often 

 catenulate, three to four in series, 10-30 u. (av. 20 u) in 

 diameter; either zoospores or germ tubes produced; in 



soil (Fig. 87 D-E) P. echinulatum Matthews, p. 1 17m 



Oospore 11.6-21.7 \l, one in an oogonium; oogonium termi- 

 nal, spheroidal, 16.6-28 \x in diameter, exclusive of the 5- 

 26.3 [x long by 2-5 \x in diameter, cylindrical, simple, or 

 bifurcated outgrowths ; antheridium androgynous, dicli- 

 nous, rarely hypogynous, one to four, clavate or oblong; 

 sporangia terminal, globose, ovoid, or pyriform, 25-35 

 by 23-30 \i, internally proliferous; hyphae 2.8-8.5 \l in 



diameter; on rice bait in water P. polypapillatum T. I to l 



Sex organs absent 



Sporangia proliferating 

 Sporangium papillate 



Sporangia on vigorously growing thalli narrowly ellipsoidal 

 130-170 by 35 \x, under less favorable conditions ovoid 

 or obpyriform, 50 by 30 \l, typically borne at the tip of an 

 unbranched, undulating sporangiophore 6-8 \x in diam- 

 eter, which characteristically widens to 12-15 \x imme- 

 diately beneath sporangium, proliferous, the secondary 

 sporangia formed within or more commonly beyond the 

 primary, sometimes by subsporangial branching as well ; 

 zoospores more or less delimited, sometimes even with 

 flagella, within the sporangium, completing maturation 

 outside in a sessile vesicle, encysted zoospores 13-15 \l in 

 diameter; dark, spherical, rough-walled chlamydospores 

 sometimes formed; hyphae 3-6 a in diameter; in water 



and soil (Fig. 87 A) P. imdidatiun Petersen, 2 p. 123m 



Sporangia spherical to elongate, 20-30 \i (av. 25 \j.) in diam- 

 eter, typically terminal, intercalary, with a well-developed 

 apical papilla, proliferous, the secondary sporangia form- 

 ed within or outside the primary; zoospores 8-10 u. long, 

 completely formed in a stalked vesicle; hyphae 1-4 \x in 

 diameter; in Spirogyra. . . P. carolinianum Matthews, p. 124m 

 Sporangium not papillate, spherical, terminal, 30 \i in diameter, 



1 J. Jap. Bot., 20: 58, fig. 2. 1944. 



2 Based chiefly on the description by Goldie-Smith (1952) and the present writer's 

 observations. P. undulatum var. litorale Hohnk (1953a), from saline habitat, seems 

 based on abnormal material. 



