The yellow-sedges, Carex flava aggregate, are for the most part common species of mire habitats, ranging from mineral-rich, calcareous fens to base-poor, acidic mires, and yet they comprise the most difficult of British sedges to identify. The characters traditionally used to distinguish the taxa are largely quantitative and tend to overlap a great deal, and what qualitative characters there are tend to be difficult to recognise in dried material.