kingdom Plantae - plants »  divisio Magnoliophyta - flowering plants »  class Rosopsida - eudicots » order Malpighiales »  family Violaceae »  tribus Violeae > genus Viola > Viola sect. Plagiostigma Godr.  > Viola subsect. Adnatae W. Becker 

Viola vaginata Maxim. 

• (=)  Viola pachyrrhiza Franch.

• スミレサイシン - 菫細辛 - すみれさいしん  Sumiresaishin 

| Bio Lib | Wild plnts in Hokkaido |Wild plants in and around Shimane  | GRIN |

Distributional Range: Native Asia-Temperate EASTERN ASIA: Japan [Hokkaidô, Honshu]

Habitat: Viola vaginata (Sumiresaishin) is a perennial plant distributed in southwestern Hokkaido and mainly in the Sea of Japan side of Honshu. One of the biggest leaves of Japanese violets. It is found beneath deciduous forests in the mountains, and blooms with early spring plants. In the Chugoku region, it is common at the foot of the Chugoku Mountains. 

References:

1. Igari, M. 1996. Wild violets of Japan Note: book almost entirely in Japanese

2. Iwatsuki, K. et al. 1993-. Flora of Japan.

3. Ohwi, J. 1965. Flora of Japan (Engl. ed.).