Scanning electron micrographs of leaves of British Carex species, 5. Subgenus Carex: sections Spirostachyae, Digitatae Mitratae Acrocystis Rhychocystis, Rhomboidales and Aulocystis

Abstract This part completes the large subgenus Carex, embracing sections Spirostachyae, Digitatae, Mitratae, Acrocystis, Rhynchocystis, Rhomboidales, Aulocystis. It opens with the section Spirostachyae, a natural group, related to Ceratocystis and to C. sylvatica; like these, they show minor variations on ‘the default caricoid leaf’. These are followed by section Digitatae, of which the core C. digitata and C. ornithopoda are closely related, five dry grassland sedges of varied affinities, C. humilis, C. caryophyllea, C. montana, C. ericetorum and C. pilulifera (the last three traditionally placed in the heterogeneous section Acrocystis). These are derived from at least four different lineages and all have their closest allies outside Europe. All have different upper-surface ornamentation. Finally, three distinctive species are included, which are the sole representatives of their sections in Britain and Ireland, C. pendula, C. depauperata, C. atrofusca. These are either isolated or omitted altogether in the DNA analyses to date.