I Molecular and morphological data were used to reconstruct the phylogeny of Camphorosmeae (Chenopodiaceae) in Australia, a tribe adapted to and widespread in the temperate arid and semiarid areas of the continent. A total of 71 species, representingnearly half of the species and all 14 currently recognized endemic genera, were sampled. Of seven molecular markers tested (ETS, ITS, the trnl.-trnF spacer, the trnP-psaJ spacer, the rpSí6 intron, the rpLí6 intron, and the trnS-trnG spacer), only the nuclear ETS and ITS provided enough variation for phylogenetic studies in the group. Phylogenetic hypotheses inferred from molecular data do not support the current taxonomy of Camphorosmeae in Australia. Neobassia, Threlkeldia, Osteocarpum, and Enchylaena should be subsumed into the species-rich genera Sclerolaena and Maireana. Of 15 morphological characters, only the fruiting perianth provided some support for the taxonomic implications of the DNA-based phylogeny. Indumentum characters, which were reported to be of taxonomic significance in several groups in Chenopodiaceae, did not provide support for the molecular phylogeny of Camphorosmeae in Australia.

Camphorosmeae (Chenopodiaceae, formerly Sclerolaeneae) are widespread across all states of Australia. Molecular data revealed that the Australian Camphorosmeae represent a monophyletic lineage comprising 147 currently recognised species, 145 of which are endemic to Australia. Like their Eurasian relatives most Australian Camphorosmeae are well-adapted to dry and saline environments, and most species are distributed in semi-arid or arid landscapes of the Eremaean area of central and western Australia. The historical biogeography of the Australian Camphorosmeae is analysed using an ETS phylogeny of the group and DIVA. We found that diversification of the tribe started at the end of the Miocene, and that radiation took place during the Pliocene, probably driven by the aridification of Australia during this time. Southern west Australia probably served as the ancestral area, and we hypothesise that the ancestors of Australian Camphorosmeae were already adapted to dry and saline conditions and might have been distributed in coastal or saline inland habitats. Successful dispersal and establishment of Camphorosmeae in the then newly developed arid regions was probably enhanced by niche pre-emption. Our timing of the radiation of this drought-adapted lineage and the directions of its dispersal support the hypothesis that the aridification of Australia started during the Late Miocene and arid areas expanded during the Pliocene from the west to the east and then north.