Transverse leaf sections of almost all British Carex species were prepared with a microtome, stained and mounted for subsequent microscopic examination. Forty five characters were then recorded and converted to binary form and analysed using numerical taxonomy methods. Different species of sedge were found to have a distinct leaf anatomy. Comparison with previous work suggests that this anatomy is consistent within most species. Analysis of similarities in leaf anatomy identified five distinct clusters. There was a high degree of agreement between the distribution of sections in this study and those obtained from those phylogenetic relationships based upon DNA sequences. The degree of conformity was higher in the sub-genus Vignea than in the sub-genus Carex. This may be related to the monophyletic nature of sub-genus Vignea compared to the polyphyletic origin of sub-genus Carex.