Appl Veg Sci. 2019;00:1–16. wileyonlinelibrary.com/journal/avsc | 1 Applied Vegetation Science © 2019 International Association for Vegetation Science Received: 25 April 2019 | Revised: 29 July 2019 | Accepted: 12 August 2019 DOI: 10.1111/avsc.12456 RESEARCH ARTICLE A formal classification of the Lygeum spartum vegetation of the Mediterranean Region Corrado Marcenò 1 | Riccardo Guarino 2 | Ladislav Mucina 3,4 | Idoia Biurrun 1 | Ulrich Deil 5 | Kamal Shaltout 6 | Manfred Finckh 7 | Xavier Font 8 | Javier Loidi 1 1 Department of Plant Biology and Ecology, University of the Basque Country UPV/EHU, Bilbao, Spain 2 Department of Biological, Chemical and Pharmaceutical Sciences, and Technologies, University of Palermo, Palermo, Italy 3 Harry Butler Institute, Murdoch University Murdoch, Perth, WA, Australia 4 Department of Geography and Environmental Studies, Stellenbosch University, Stellenbosch, South Africa 5 Department of Geobotany, Faculty of Biology, University of Freiburg, Freiburg im Breisgau, Germany 6 Faculty of Science, Tanta University, Tanta, Egypt 7 Biodiversity, Ecology and Evolution of Plants, Institute for Plant Science and Microbiology, University of Hamburg, Hamburg, Germany 8 Plant Biodiversity Resource Centre, University of Barcelona, Barcelona, Spain Correspondence Corrado Marcenò, Department of Plant Biology and Ecology, University of the Basque Country UPV/EHU, Bilbao, 48080, Spain. Email: marcenocorrado@libero.it Funding information CM, IB and JL were funded by the Basque Government (IT936‐16). Co‐ordinating Editor: Florian Jansen Abstract Aims: We examined all available literature and some unpublished data on the We examined all available literature and some unpublished data on the grasslands domi‐ nated by Lygeum spartum from Southern Europe and North Africa to produce a for‐ malised classification of this vegetation and to identify the main factors determining its plant species composition. Location: Mediterranean Basin and Iberian Peninsula. Methods: We used a dataset of 728 relevés, which were resampled to reduce unbal‐ anced sampling effort, resulting in a dataset of 568 relevés and 846 taxa. We classified the plots by TWINSPAN, interpreted the resulting pools, and used them to develop formal definitions of phytosociological alliances characterised by L. spartum vegetation. The definitions were included in an expert system to assist automatic vegetation classi‐ fication. We related the alliances to climatic factors and described their biogeographical features and ecological preferences. The floristic relationships between these alliances were analysed and visualised using distance‐based redundancy analysis. Results: We defined eleven alliances of L. spartum vegetation, including the newly described Launaeo laniferae–Lygeion sparti from SW Morocco and the Noaeo mucro‐ natae–Lygeion sparti from the Algerian highlands and NE Morocco. Biogeographical, climatic, and edaphic factors were revealed as putatively driving the differentiation between the alliances. Vegetations of clayey slopes and inland salt basins displayed higher variability in comparison with those of coastal salt marshes. Main conclusions: A comprehensive formal classification, accompanied by an ex‐ pert system, of the grasslands from Southern Europe and North Africa dominated by Lygeum spartum vegetation was formulated. Eleven phytosociological alliances were recognised, whose plant species composition is influenced by biogeographic, climatic, and edaphic drivers. The expert system, containing formal definitions of the phytosociological alliances, will assist in identifying the syntaxonomic position of new datasets. KEYWORDS badlands, dry grassland, expert system, Lygeo‐Stipetea, Lygeum spartum, Mediterranean region, Phytosociology, Salicornietea fruticosae, salt marsh, vegetation classification