Phylogenetic analysis of Macromeria based on 35 morphological characters produced a single most parsimonious tree that supports the monophyly of the genus. The phylogeny supports previous evaluations of relationships among species, and the resulting clades often connect sister taxa that are geographically proximate. Mapping of corolla size onto the phylogeny indicates that floral size has changed many times within the genus, and that the very large corolla size in southern populations of Macromeria viridiflora has been derived from a smaller-flowered ancestor.

Key words: Boraginaceae, Macromeria, morphology, phylogenetics