The impact of Verne Grant's 1981 edition of Plant Speciation reverberates as strongly today as it did 22 yr ago. His insights into the field of plant evolutionary biology continue to inform current and future research programmes. For example, Grant's work pointed the way for those who have argued that the consequences of natural hybridization are of primary importance in the evolution of many plant and animal species complexes. It is thus now widely accepted that numerous, important outcomes are afforded by crosses between divergent lineages. In the present paper we highlight some of the concepts that appear in Grant's seminal work. We address these in the context of their application by Grant to a plant species complex that we have studied for 15 yr, the Louisiana Irises. We consider Grant's inferences in light of new data and our own conclusions. In the main, we find ourselves supporting Grant's conceptual framework.