Other vegetation of the same general type as the Hyperico-Potametum and characteristic of similar, seasonallyinundated habitats with rather base-poor and only moderately enriched waters, undoubtedly occurs in Britain, but it has been very poorly sampled. Some, lacking Hypericum elodes but otherwise essentially the same as the Hyperico-Potametum, could perhaps be regarded as impoverished stands of that community, though it must be noted that species such as Potamogeton polygonifolius, Eriophorum angustifolium, Juncus bulbosusfkochii and Sphagnum auriculatum also occur with some frequency in bog-pool and poor-fen vegetation.

Then, there are stands in which Eleocharis multicaulis is strongly dominant with little or no H. elodes or P. polygonifolius, and some at least of these look very similar to the Eleocharitetum multicaulis Tüxen 1937 which has been recorded from Eire (Braun-Blanquet & Tüxen 1952, Brock et al. 1978, van Groenendael et al. 1979; see also Ivimey-Cook & Proctor 19666) and from other parts of western Europe (Schoof van Pelt 1973,

Dierssen 1975, 1982). White & Doyle (1982) list Deschampsia setacea as a characteristic species of such vegetation and this national rarity is certainly typical, in Britain, of this general kind of habitat. Scirpus fluitans can also be found dominating in swards which lack some of the most typical Hyperico-Potametum plants and, in the New Forest and Cornwall, Baldellia ranunculoides is a frequent and conspicuous component of low-growing vegetation in seasonally-wet pools. In the Burren, the latter kind of assemblage was designated the Baldellio-Littorelletum by Ivimey-Cook & Proctor 19666, although there the habitat was characterised by baserich and calcareous waters.

In the latest revision of the Littorelletalia by Dierssen (1975), all these vegetation types are grouped together with the Hyperico-Potametum in the Hydrocotylo-Baldellion alliance, a group comprising assemblages of mesotrophic to oligotrophic, and periodically-fluctuating waters. Other Littorelletalia communities, mostly falling in the Isoetion lacustris and Lobelion dortmannae, are dealt with in the chapter on aquatic vegetation.