Summary. The rattan palm, Calamus inops Becc., and the related taxa C. pedicellatus Becc., C. robinsonianus Becc. and C. orthostachyus Furt., that together form a natural group, are described in detail and their relationship with other species of Calamus discussed. Attention is drawn to the unreliability of local names of rattans and to the need for proper scientific vouchering of rattan research projects. range of species which share similar end-use properties. With the increase in interest in the possibility of growing rattan as a commercial crop there has been much activity in setting up silvicultural trials and in performing tests on the mechanical properties of harvested cane. Unfortunately, some of these studies lack a firm scientific base, because local or trade names have been used uncritically, and the studies are not vouchered with herbarium specimens. One of the most confused areas of rattan trade nomenclature concerns a good quality cane originating in the wild in Sulawesi (Celebes) and known as "rotan tohiti". This cane is regarded as being the premier large-diameter cane from Sulawesi, and in view of this has been the subject of several recent studies. The taxonomy of Sulawesi rattans is still poorly known. There are approxi- mately 45 species that have been recognised in the field and the herbarium, but of these only approximately one half have validly published binomials-in other words, there are many undescribed taxa. A common source of information on the rattans of Sulawesi is Heyne's De Nuttige Planten van Nederlandsch Indie (Heyne 1922). In this work the author listed the useful plants of the Indonesian region; many of the observations are vouchered by herbarium specimens, lodged in Herbarium Bogoriense. Heyne sent material of the palms to Beccari in Florence, shortly before the latter died in 1920. Beccari had provided names for many of the specimens and communicated them to Heyne, but did not have time to describe the new taxa formally. Heyne, however, published the new names,