A checklist of indigenous flora in the Richtersveld National Park confirms high plant diversity in the arid north-western tip of South Africa

As a basis for conservation planning, a first comprehensive vascular plant species checklist for the core Richtersveld National Park was compiled, based on the collection of more than 3000 new herbarium vouchers and in total studying over 8000 specimens and more than 4000 iNaturalist observations. By the end of April 2024, a total of 1077 indigenous taxa were recorded. The documented indigenous flora included 14 pteridophytes, 3 paleodicots, 246 monocotyledons and 815 dicotyledons. A total of 99 indigenous families and 392 genera were recorded. The largest family was the Asteraceae, and the second largest family was the Aizoaceae. In addition, 44 taxa were identified as invasive or alien flora. Seven species were regarded as extinct; of these, four species disappeared in a context of diamond mining, and three species were no longer found after the recent drought 2014 to 2022. The role of the peculiar biogeographical position and the high diversity of unique habitats within extreme environmental gradients were discussed in a review of published evidence. Reference to distribution and habitat was presented for each species in the appendices. Conservation implications: The article offers a complete checklist of vascular plants that forms a baseline for monitoring, and which facilitates the identification of additional taxa. In addition, a total of 125 taxa listed on the SANBI Red List and 15 taxa on the International Union for Conservation of Nature (IUCN) Red List were recorded, as well as a total of 170 taxa of conservation concern. Twenty-nine taxa are listed as endangered, and 21 taxa were listed as critically endangered on the South African red list. A total of 38 taxa were regarded as endemic and 101 taxa as near endemic. The identification of these taxa in combination with the information on their habitat preferences and distribution will allow targeted conservation planning.