Question: How do lawn floras compare with those of semi-natural grasslands? Are the compositions of lawn toms determined by local, within-garden factors (e.g. lawn management and size) or by regional factors (e.g. climate and location)? Are lawn floras nested (like semi-natural grasslands) or not (like cultivated parts of gardens)? Are there gradients of species composition within lawns? Location: Sheffield, UK. Methods: We examined the composition of the floras of entire lawns and of two 1-m² lawn quadrats in 52 gardens. Results: A total of 159 species of vascular plants was recorded, 60 of them only once. Most lawn species were forbs, but most lawn cover consisted of grasses. Lawn species were predominantly natives. Bigger lawns had more species, but richness was not closely linked to other environmental or management variables. Composition of lawn floras varied with altitude, with woodland and wetland plants more common in the higher west of the city, and weeds of waste ground in t