The dataset gathers information on the 954 cropland and 5619 grassland plant assemblages studied in the research article Functional biogeography of weeds reveals how anthropogenic management blurs trait-climate relationships by Bourgeois, B., Munoz, F., Gaba, S., Denelle, P., Fried, G., Storkey, J. and Violle, C. published in the Journal of Vegetation Science. A R script for analyzing data is also provided. Data include: SURVEY.ID: unique identifier of the plant survey; HABITAT: type of habitat (2 levels: cropland - grassland); CROP TYPE: type of annual crop cultivated for croplands (4 levels: maize - oilseed - sunflower - winter cereal); HERBICIDE TREATMENT: herbicide treatment for croplands (2 levels: herbicide-free - herbicide-sprayed); CWM SLA: Community-Weighted Mean of Specific Leaf Area (in m2 / kg); CWM LDMC: Community-Weighted Mean of Leaf Dry Matter Content (in mg / kg); CWM LNC: Community-Weighted Mean of Leaf Nitrogen Content (in mg N / kg); CWV SLA: Community-Weighted Variance of Specific Leaf Area (in m2 / kg); CWV LDMC: Community-Weighted Variance of Leaf Dry Matter Content (in mg N / kg); CWV LNC: Community-Weighted Variance of Leaf Nitrogen Content (in mg / kg); GSLtw: Growing Season Length (in days) accounting for both temperature and soil water limitations; Xcoord, Ycoord: coordinates of the plant survey. Please contact the authors for further information.