Helwingia japonica is accepted species in  the family Helwingiaceae   
Genus Helwingia 
This species is found in Japan (incl. Ryukyu Islands), Korea, Taiwan, Myanmar, Bhutan, Vietnam, India: Assam, Sikkim, China: Anhui, Fujian, Gansu, Guangdong, Guangxi, Guizhou, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Shaanxi, Shandong, Shanxi, Sichuan, Yunnan, Zhejiang.