Stoneworts, or charophytes as they are frequently known, have an unusual place in British botany. Although they are algae, their complex structure and superficial resemblance to some aquatic plants mean that they have frequently been studied by botanists, who normally restrict their study to higher plants. Indeed, they are included within the remit of the Botanical Society of the British Isles, which has published an identification guide for the group (Moore 1986).