1060 AQUATIC PHYCOMYCETES 



Phytophthora oryzae (Ito and Nagai), Waterhouse 



Trans. Brit. Mycol. Soc, 41 : 200. 1958 



(Fig. 90 A-B, p. 1059) 



Pythiomorpha oryzae Ito and Nagai, J. Fac. Agr. Hokkaido Imper. Univ., 

 Sapporo, 32: 51, pi. 8, fig. 9, pi. 9, figs. 1-6. 1931. 



"Mycelia extra- and intra-matrical ; hyphae non-septate, branched 

 monopodially, often swollen in knob-like appearance at irregular inter- 

 vals, 3.5-1 1 \i mostly 6-8 \i in width. Sporangia ovoid, ellipsoidal or 

 somewhat elongated, 41-84 X 26-48 [jl mostly 60-84 x 29-43 jjl in size; 

 later sporangia produced on the hyphae proliferated onwardly through 

 the empty ones, or on the lateral branch from the base of them. Zoo- 

 spores ellipsoidal or kidney-shaped, about 12 x 7 \x, matured in the 

 sporangium, swarming out directly or discharged being wrapped with 

 the vesicle-membrane which is soon broken off by the self-agitation of 

 the zoospores, and then swarming away. Oogonia and antheridia absent. 

 Gemmae globular or somewhat irregular in shape, intercalary. Hyphal 

 clumps produced on cornmeal agar" (Ito and Nagai, be. cit.). 



On rotted rice seeds and on seedlings in rice fields, Japan. 



"Pythiomorpha Sp. I" of Lund (1934: 49, fig. 24 a-b) may possibly be 

 referable to this species. It was found on twigs of Salix in Denmark. 



