Phylogenetic implications of pollen morphology and ultrastructure in the Barnadesioideae (Asteraceae) and related taxa

The subfamily Barnadesioideae of Asteraceae consists of nine genera and approximately ninety species. The subfamily is considered to be basal and the sister group to the rest of the family. This relationship has been based not only on molecular evidence, but also on palynological data. I have used Scaning and Transmission Electron Microscopy to study pollen of seventy species of all genera of Barnadesioideae and representatives of related families (Calyceraceae, Goodeniaceae, and Campanulaccae). The results suggest that the genus Chuquiraga may be the basal group of the Barnadesioideae. Within Barnadesioideae, the trends in pollen evolution vary from grains that have intercolpar regions without concavities to strongly concave pollen to psilolophate grains. The tribe Mutisieae is one of the basal lineages in the Asteraceae. It is important to understand the origin and evolution of Barnadesiieae-Mutisieae complex to understand the origin and evolution of the Asteraceae. Pollen grains of 62 genera (Mutisieae comprises 84 genera) were examined. Phylogenetic analyses reach the following conclusions: (1) the evolutionary trend in the Mutisieae is from Gochnatiinae to Mutisiinae and Nassauviinae. (2) Nasauviinae is a monophyletic group, Gochnatiinae and Mutisiinae are not monophyletic. (3) the problematic genera Adenocaulon and Eriachaenium should be placed in Nassauviinae. Calyceraceae (the family contains six genera and approximately 50 species) has gained attention for being a potential sister group to Asteraceae. In particular, the presence of intercolpar concavities in both Calyceraceae and Barnadesioideae has been proposed as a possible synapomorphy. Pollen grains from all six genera of Calycerace were examined And the results suggest that the presence of intercolpar concavities in the Barnadesioideae and Calyceraceae may be a parallelism.