"Oka-sumire" (Viola phalacrocarpa f. glaberrima) belongs to the family Violaceae (the Viola family). It is a perennial herb that is native to Japan, the Korean Peninsula, China and Siberia. This herb grows in sunny wood edges and roadsides, and can reach 5-10 cm in height. The leaves are spatulate, long-deltoid or long-ovate. The bright magenta flowers bloom from April to May. It is devided that the spurs are elongate and the bases of lateral petals are covered thickly hairs. It is not pubescent on its peducle and leaves, different from "Akane-sumire" (Viola phalacrocarpa).