菌落在CMA上呈放射状。菌丝无隔，老后有隔，不规则分枝，粗3.1-5.1μm。Pythium gracile sensu auct.， non Schenk: Hsieh， Studies on genera Pythium and Pythiogeton. MS Thesis， Nat. Taiwan Univ. p. 37. 1976; Matthews， Studles on the Genus Pythium p. 27. 1931; Middleton， Mem. Torrey Bot. Club 20(1): 31. 1943.