Abstract
A synopsis of Heliotropiaceae in Thailand is presented and, as part of this, the taxonomic history, identification keys, distribution maps, herbarium specimen citations and diagnostic characters are provided. Two genera and 12 species are recognised and four new combinations are proposed of Tournefortia under the genus Heliotropium, namely H.hookeri, H.intonsum, H.montanum and H.ovatum. Two species are newly recorded in Thailand: Euplocaovalifolia and H.hookeri. The neotype and lectotype are designated here for Tournefortiamontana and T.boniana, respectively.