Pedunculate Club-rush Bolboschoenus laticarpus (Cyperaceae) ? an overlooked native or a spreading neophyte?

Abstract

Bolboschoenus laticarpus Marhold, Hroudová, Zákravský & Duchá?ek (for which we suggest the common name Pedunculate Club-rush) is reported from the British Isles and the characters which distinguish it from B. maritimus (L.) Palla are given. The known English distribution is presented and placed in its wider geographical context. The ecology and history of this species in Britain are outlined and its likely status is considered. B. laticarpus is locally abundant and widely distributed in a range of natural and artificial habitats, particularly within the Somerset Levels and also in the flood plains of some larger rivers, where it is now known to have been long persistent. B. laticarpus appears to be a successful colonist, having arrived recently in several newly created, artificial habitats. The mode of introduction is unknown but believed to be natural, and indeed elsewhere in Europe it is reportedly increasing within its natural range, perhaps as a consequence of changes in land-use, eutrophication and potentially climate. We therefore regard it as a native taxon.