This account presents 62 vascular plant genera, comprising 162 species, currently known only from Borneo, with photographs and maps of their known and potential distributions. Borneo’s exceptionally high plant diversity is threatened by rapid land-use change, hence, assessing threats to species uniquely found there, and identifying areas where a significant proportion are harboured, are urgent tasks. Centres of endemism especially found in northwest Borneo are considered against remaining forest cover and protected areas to highlight plant conservation exigencies. The book is updated from the author’s research which was awarded the International Society for Plant Molecular Biology 2021–2022 Gold Medal for most outstanding doctoral thesis in plant science research at the National University of Singapore.