Millettia leucantha or sathon is a species of plant in the legume family, Fabaceae. It is a perennial flowering tree native to Indo-China – Cambodia, Laos, Myanmar, Thailand, and Vietnam – as well as Bangladesh and southern Yunnan province in China.
It is the provincial tree and flower of Khorat or Nakhon Ratchasima Province in Isaan (Thailand), where it is known as sathon (สาธร).
Two varieties are recognized:
Sathon sauce is a flavouring sauce used in Isaan cuisine. The leaves of two species of Millettia are used for making sathon sauce: Millettia utilis and Millettia leucantha var. buteoides (aka Imbralyx leucanthus var. buteoides).[1] This sauce used for cooking is the only OTOP product made from the sathon tree.[2]