Aim Species–area relationships ( SAR s) on oceanic archipelagos are shaped at least as much by speciation as by immigration–extinction dynamics. We examine three well‐studied Atlantic archipelagos to quantify the relative contributions of colonization and diversification to individual and whole‐archipelago floras. Location Three Macaronesian archipelagos: the Azores, Madeira and Canary Islands. Methods We assessed the floras o...