I thank the Kew TOBU Fund for financial support of fieldwork in Vietnam, Thailand and the Lao P.D.R. The Keepers and Curators of the following herbaria are thanked for assistance during visits and for the loan of material: AAU, B, BM, BK, BKF, BO, C, CAS, CMU, E, F, GH, HAST, HN, HNU, K, KKU, KUN, KYO, L, LE, MO, NY, P, PSU, SAI, SING, TAI, TCD, UKM, UKMB, UNM, UC, US. The staff of BK, BKF, HN and HNU and KUN is gratefully acknowledged for their invaluable assistance and splendid company during fieldwork. Thanks are due to Linda Gurr for skilfully executing the illustrations, to Dr. Ching-I Peng, Institute of Botany, Academia Sinica, Taiwan, for providing living material of Taiwanese P. chinensis for study, to Alan Radcliffe-Smith for providing the Latin diagnoses and to Dr A. Hay, Dr Dan Nicolson and Dr Simon Mayo for critically reviewing the manuscript. Special thanks are due to Kerry Taylor, University of the West of England, a placement student who worked at Kew during 1996 – 97 compiling an ALICE database of economically useful aroids, for contributing the ethnobotanical data included in this paper.