Discovering Polycnemoideae - an old, rare, strangely distributed and largely unknown subfamily of the Amaranthaceae/Chenopodiaceae alliance

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Molecular studies have shown that the Amaranthaceae/Chenopodiaceae alliance (A/C alliance) consist of three major lineages, the predominantly tropical Amaranthaceae s.str. (c. 1000 spp.), the largely subtropical and warm-temperate, often halophilous Chenopodiaceae (c. 1230 spp.) and the Polycnemoideae (16 spp.). While the two speciesrich lineages Chenopodiaceae and Amaranthaceae have been or are currently studied in detail, little is known about the species-poor Polycnemoideae. To understand the evolution of the A/C alliance it is essential to learn more about the phylogeny, ecology and biogeography of this small subfamily. Polycnemoideae originated during the early Eocene and consist of three small, disjunctly distributed genera, Polycnemum (6 spp.; Eurasia), Hemichroa (3 spp., Australia) and Nitrophila (7 spp.; amphitropical in America) that are inconspicuous herbs growing in various open habitats including ruderal or saline sites and agricultural land. This project uses dated molecular phylogenies and detailed surveys of the morphology and distribution of all c. 16 species to discover 1. their ancestral range, habitat preferences and morphology and 2. their modes of morphological, ecological and biogeographical diversification. I would like to find out whether Polycnemoideae represent relicts of an old diversification or a young diversification of an old lineage, and trace the sequence of their major inter- and intracontinental dispersal events.