This book is a field guide to the (primary) lowland forest of East Kalimantan. The manual describes 280 tree species, covering some 66 families, of the Balikpapan-Samarinda area that are economically or ecologically important. Keys are presented for the identification at the family and species level. All species are described by habitus, morphological characteristics (stem, bark, resInside, leaves and fruits) and general ecology. Attention is paid to the distribution of the species in and outside the research area and the products the species provide. Furthermore literature references and vernacular names are given. Accurate drawings of the leaves and the reproductive organs of selected species are presented. The Bahasa Indonesian translation of this manual is available as Tropenbos-Kalimantan Series no. 2.