Ontogeny of Inflorescences and Flowers in the Brownea Clade (Fabaceae: Detarioideae): A morphologically diverse lineage of legumes

The subfamily Detarioideae stands out among legumes as a clade with remarkable diversity in floral morphology. Within this subfamily, the Brownea clade, characterized by its Neotropical distribution, exhibits significant meristic variability in the perianth, androecium, and gynoecium. These structures vary in size, shape, color, and pubescence. This floral diversity is associated with different pollination syndromes, including entomophily, ornithophily, and chiropterophily. Despite the monophyly of the Brownea clade, the phylogenetic and taxonomic relationships among its seven genera remain inadequately resolved. In such groups, studies on floral ontogeny are crucial to understanding the processes driving variations in floral morphology. These studies also aim to identify potential autapomorphies, synapomorphies, plesiomorphies, and homoplasies that could aid in the systematics of the group. This study aims to expand the understanding of the morphology and development of inflorescences and flowers in six species from five morphologically diverse genera within the Brownea clade. The study provides ontogenetic descriptions of Brownea longipedicellata, Browneopsis macrofoliolata, Heterostemon mimosoides, Macrolobium suaveolens, Paloue paraensis, and Paloue speciosa, comparing these findings with existing studies on Detarioideae. In doing so, it contributes to the broader understanding of floral evolution in the Leguminosae family. In addition to supporting the systematics of the group, the study explores how floral morphological adaptations relate to their respective pollination syndromes. Given the lack of studies addressing the nectariferous nature of flowers in this clade, we also conduct anatomical analyses of the hypanthium in these species to enhance knowledge of their systematics at an anatomical level