Additional file 1. Data table of geography, demography, ethnicity, and used medicinal plants by district

Additional file 1. Data table of geography, demography, ethnicity, and used medicinal plants by district

We evaluated the boundaries among Nymphoides (Menyanthaceae) species in Africa, a region where the genus has received relatively little study. We gathered morphological data from seeds using light and scanning electron microscopy, and we conducted molecular phylogenetic analyses using nuclear sequence data from the internal transcribed spacer (ITS) region. Morphological and molecular features distinguished six species and affirmed their respective geographic ranges. No African specimens were attributable to Nymphoides indica, even though this paleotropical species previously had been understood to grow in Africa. We establish the new combination Nymphoides senegalensis (G. Don) Tippery, based on an established African basionym, to accommodate the specimens formerly identified as N. indica. Phylogenetic analyses resolved two distinct clades containing African species. The majority of African species are closely related to neotropical species, with which they share similar petal ornamentation. The morphologically distinct N. ezannoi shares floral and phylogenetic similarity with species from North America and Asia. Results presented here support prior hypotheses that allopolyploid species in the Americas may have originated from one or more parental lineages in Africa. Seed morphological characters remain some of the most reliable features for identifying species, particularly for herbarium specimens lacking observable floral characters.

The floating-leaved aquatic plant genus Nymphoides includes diploid and polyploid species that are distributed worldwide. Prior studies found widespread incongruence between nuclear and plastid phylogenies, and this has prevented the construction of a unified phylogenetic hypothesis for the genus. In order to examine whether phylogenetic incongruence resulted from ancestral polyploidization events, we obtained DNA sequence data from two nuclear loci, phytoene desaturase (PDS) and transmembrane nine (TMN1), as well as the plastid trnT-trnF region. Multiple divergent copies of the nuclear genes were recovered from several species, and species with the most divergent copies were inferred to have originated through allopolyploidization. Our data support a scenario in which three groups of species descended from allopolyploidization events: a clade of North American species (N. aquatica and N. cordata), a clade of neotropical species (N. fallax, N. grayana, and N. humboldtiana), and the Australian species N. montana. Trees constructed using novel nuclear gene data also were incongruent with previously generated nuclear and plastid data, however we were able to combine data from four independently evolving regions (PDS, TMN1, nuclear internal transcribed spacer, and plastid) to generate a single species tree that received strong support at several nodes. Sources of incongruence on the species tree involved a relatively small subset of species. Overall, the increased data from nuclear loci has dramatically improved our understanding of the Nymphoides phylogeny.