This volume covers the families Apocynaceae, Primulaceae, and Sapindaceae. Apocynaceae consists of about 155 genera and 1700 species primarily in the tropics and subtropics. Forty-two genera (6 introduced) and 125 species (10 introduced) are found in Thailand. Primulaceae consists of 22 genera with about 1000 species mainly in temperate and mountainous regions of the northern hemisphere. Three genera and 18 species are native to Thailand. Lastly, Sapindaceae consists of 140 genera and c. 1350 species, widespread in all tropical and subtropical regions of the world. Twenty-three genera and 41 species are found in Thailand.