The vascular plant flora of Batu Caves, a tower karst limestone formation, includes 269 species; 51 species (19%) are Peninsular Malaysian endemics and 80 species (30%) are calciphiles of which 56 (21%) are obligate calciphiles and 26 species are obligate calciphiles endemic to Peninsular Malaysia. Four taxa are endemic to Batu Caves itself. That Batu Caves harbours a sizeable fraction (21.4%) of Peninsular Malaysia's limestone flora underlines the need for detailed checklists of each and every limestone hill to enable adequate planning of conservation programmes to support biodiversity. Because botanical collecting began in the 1890s, Batu Caves is important as the type locality of 24 plant species. Land-use pressures have over time eliminated the surrounding native vegetation, leaving the flora vulnerable to aggressive weedy and alien species. Although designated as a Public Recreation Area, its protection status needs to be enforced and the boundaries clearly marked.