Abstract: The present paper is an extension of my revision of Chinese species of the genus Lysimachia published in 1979 (Acta Phytotax. Sin. 17: 21-53). The area under consideration comprises Burma, Thailand and Indo-China. They are closely associated with southern China geographically and floristcally. However, since Bonati’s account for Lecomte’s Flore Generale De L’Indo-Chine (1930) recorded 11 species, and Fletcher’s enumeration listed 12 species from Thailand (Florae Siamensis Enumeratio 2: 323-325, 1938), there has been no detailed systematic study on this genus of the whole area, although many new species have been described and published in different journals. During this study, I have had an opportunity of studing all the materials in the herbaria Edinburgh, Kew, British Museum (N. H.) and Paris. Thanks to these institutions, I am able to judge the species known to occur in this region and present an up-to-date account with a key for identification of all taxa (25 species, 1 subspecies and 2 varieties) and a brief enumeration of their synonyms and geographical distribution. L. chenii, L. remotiflora are described as new; L. insignis, L. microcarpa and L. prolifera are for the first time reported from this region, and the disused name L. siamensis Bonati is reinstated. Furthermore, some additional descriptions or notes on species previously very incompetely known are also included.

Key words: Lysimachia, Burma, Thailand, Indo-China