How many species of seed plants are there?

Abstract

Abstract Recent estimates of the number of described species of seed plant have varied by as much as 62%. The underlying methodology of these estimates is characterised and discussed. We present a revised figure for the number of seed plants based on estimating rates of synonymy in a sample of recently monographed taxa. We conclude that some recent figures overestimate the number of described seed plant species by more than 200,000. This discrepancy is explained by an over­reliance on checklists and floristic studies that underestimate synonymy rates.