This dataset aimed to assess the joint effect of the environment and plant-plant interactions in the phylogenetic pattern of semiarid plant communities. Data were obtained for 11 30 m x 30 m sites across a rainfall gradient in Spain. We assessed species co-occurrence at two different scales, at the site-level, using 80 1.5 m x 1.5 m quadrats, and at the microsite-scale, using 30 0.5 m x 0.5 m quadrats beneath three different microsites (open areas, stipa tenacissima tussocks and quercus coccifera shrubs). From the data at the site-scale we obtained plant species richness, plant co-occurrence metrics (C-score, Species combination indices) and the phylogenetic pattern of the plant community. See associated article for further details. From the data at the patch-scale we obtained similarity indices and the phylogenetic pattern of those species that were more abundant beneath a nurse than in the open. The dataset was complemented with climatic data available in the literature (Ninyerola M, Pons X y Roure JM. 2005. Atlas Climático Digital de la Península Ibérica. Metodología y aplicaciones en bioclimatología y geobotánica. ISBN 932860-8-7. Universidad Autónoma de Barcelona, Bellaterra). More details in the data can be obtained both in the metadata spreadsheet in the Excel file. Empty data is in blank. There is only one empty space (MPDfac in the Camporreal site). Data was taken by S. Soliveres and F.T. Maestre, both authors of the associated paper. Contact for further information: Dr. Santiago Soliveres (e-mail: