Big angiosperm genera are priorities for conservation

Species in big angiosperm genera (≥500 species) are often considered to be less well-known than those in smaller genera. Consequently, species in big genera are likely underrepresented in conservation at all levels, from analyses to actions. However, emerging evidence indicates that species in larger genera tend to have smaller geographic ranges (a strong correlate of increased extinction risk). Here, we test the generality of this pattern by quantifying the relationships between plant taxon size, extinction risk and climatic zone on a global scale. We find that species in larger genera are more likely to have small ranges, less likely to have a global Red List assessment, and, when assessed, are more likely to be threatened. Persistent obstacles to improving conservation documentation of big genera include taxonomic uncertainty, data shortfalls and number of species involved, requiring continued collaboration between taxonomy and conservation to reduce this bias and enable effective conservation of the quarter of plant species that big genera encompass. Article Impact Statement Species in big angiosperm genera are under-studied, under-assessed, and their extinction risk has been underestimated.