Japan Flora: Leaves ovate to rhombic-orbicular, sometimes depressed, 6-15 cm. long and as wide, 3- to 5-nerved; sepals broadly lanceolate to ovate-oblong, 2.5-4 cm. long, obtuse, sometimes subacute, herbaceous, green, the petals white, ovate or elliptic, 25-4.5 cm. long, obtuse; anthers linear, (10-)12-15 mm. long, the filaments 3-5 mm. long; ovary conical; stigma rather thick. May-June.
Hokkaido. Kuriles, Sakhalin, Korea, Manchuria, Ussuri, and Kamchatka.