The problem of polymorphism in the Calamus javensis complex has been examined by various techniques in several publications. A wide range of morphological variation was identified during these studies. Characters showing high variation were leaf sheath and ocrea morphology, number and arrangement of leaflets, length and arrangement of the rachillas. All names used in the complex are here regarded as synonyms of C. javensis except C. tenompokensis, which is retained as a distinct species. One variety is recognized, C. javensis var. polyphyllus (including C. acuminatus). Using morphological characters, we recognized 11 informal (often not monophyletic) forms within C. javensis var. javensis. Here we present identification keys, descriptions and notes of all recognisable forms, varieties and species included in the Calamus javensis complex. © 2023 Nordic Society Oikos. Published by John Wiley & Sons Ltd.