A vouchered and georeferenced checklist of the endemic vascular plant species of the Lesser Sunda Islands highlights data deficiencies and threat levels.

A checklist of the 319 endemic vascular plants of the Lesser Sunda Islands is presented, derived from specimen data and expert-verified georeferences. The majority of these endemic plant species are single-island endemics (251 species). Timor is the richest in endemic plant species, with 82 single-island endemics, despite Flores (46 endemics) and Sumbawa (38 endemics) being islands of similar size. Of the 121 species that have been Red Listed, 45 are Data Deficient and 56 are in threatened categories. The persistence of many of these species is uncertain, with 51 not collected since the 19 century. We hope that this baseline data will spur targeted searches for these species, highlight taxonomic gaps, and aid conservation planning decisions.