European plants with C4 photosynthesis: geographical and taxonomic distribution and relations to climate parameters

A survey of C₄ plants in Europe was performed with 216 species based on information in the literature and new studies. C₄ species were found in 10 families: the eudicots Amaranthaceae, Chenopodiaceae, Euphorbiaceae, Molluginaceae, Nyctaginaceae, Polygonaceae, Portulacaceae and Zygophyllaceae and the monocots Cyperaceae and Poaceae. The majority of the C₄ species belong to four families, Amaranthaceae (23), Chenopodiaceae (65), Cyperaceae (27) and Poaceae (88). In central and southern Europe, the abundance of native C₄ plants varied between 44 and 88% of total C₄ plants occurring, the rest being invasive C₄ species. The occurrence of total C₄ species, C₄ monocots and C₄ Chenopodiaceae was assessed for five major phyto‐geographical regions of Europe (north‐west, north‐east, central, south‐west, and south‐east). The abundance of C₄ plants of total C₄ dicots, C₄ Chenopodiaceae, total C₄ monocots, C₄ Poaceae and C₄ Cyperaceae was related to the climatic variables of annual mean daily temperature, annual precipitation and DeMartonne's aridity index. The abundance of total C₄ plants decreases with increasing temperature and expression of aridity (decreasing aridity index) and is not correlated with precipitation. The abundance of total C₄ dicots and C₄ Chenopodiaceae is correlated with precipitation and aridity but not temperature, whereas the abundance of total C₄ monocots, C₄ Poaceae and C₄ Cyperaceae is correlated with temperature and aridity but not precipitation. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 163 , 283–304.