We examined 11 species in four genera of rattans (Calamus Daemonorops. Korlhalsta. Plectocoma) growing in their native rainforest habitat in Singapore Using aqueous safranin dye we found that >95% of all vascular bundles at the base of a mature stem were functioning to transport water. We determined the frequency of vessel lengths in the long stems of these climbing palms by infiltration with dilute latex paint Separate length distribution were made for metaxylem and protoxylem vessels in both. there were many short and a few long vessels. The longest protoxylem vessels ranged from 7.5 to 62 cm in length but one stein had an exceptional protoxylem vessel measuring 3.0 m. Maximum metaxylem vessel diameters were positively correlated to maximum vessel lengths in these species The longest metaxylem vessel was found in K rigida and was 3 96 m in length and was constructed from similar to1200 vessel elements (cells). The widest vessel in that same stein was 532 mum in diameter. Long. wide vessels decrease resistance and increase water transport efficiency In addition we suggest that wide metaxylem vessels may have an important function in water storage.