Systematics and evolution of inflorescence structure in the Tradescantia alliance (Commelinaceae)

The Tradescantia alliance (subtribes Tradescantiinae and Thyrsantheminae of tribe Tradescantieae, family Commelinaceae) comprises a group of closely related New World genera exhibiting considerable variation in morphological, life history, and genomic traits. Despite ecological and cytogenetic significance, phylogenetic relationships among genera and species remain uncertain. In particular, variation in inflorescence morphology has confounded classification and taxonomy. The presence of self compatible and incompatible species allowed us to test the hypothesis that self compatible species will have condensed inflorescences. We inferred phylogenetic relationships using two plastid loci (rpL16, trnL-trnF) for 85 taxa in Commelinaceae, with sampling focused in the Tradescantia alliance. Constraint tests supported only subtribe Tradescantiinae, Tripogandra and Tinantia as monophyletic, with Tripogandra nested within Callisia. We estimated ancestral states for both breeding system and inflor...