Hallier ²) subdivided the Convolvulaceae into two groups, viz. the Psiloconiae, with smooth pollen grains, and the Echinoconiae with spinose ones. The genera of the Psiloconiae occurring in Malaysia have been dealt with in parts I and II of the present paper, with exception of the genus Erycibe, which shall be treated in a special monograph. The group of Echinoconiae contains two tribes, viz. 1. Ipomoeeae and 2. Argyreieae, both represented in Malaysia. The genus Ipomoea belongs to the Ipomoeeae.