Counting counts: revised estimates of numbers of accepted species of flowering plants, seed plants, vascular plants and land plants with a review of other recent estimates

We present revised estimates of the numbers of accepted species of flowering plants (369,434), seed plants (370,492), vascular plants (383,671) and land plants (403,911) based on a recently de-duplicated version of the International Plant Names Index and rates of synonymy calculated from the seed plant families published in the World checklist of selected plant families. Alternative approaches to estimating or calculating the number of accepted plant species are discussed and differences between results are highlighted and interpreted.