Synonymy

Littorella-Lobelia associes Pearsall 1918; Eleocharitetum acicularis Koch 1926 p.p.; Isoeto-Lobelietum (Koch 1926) Tx. 1937 p.p.; Eleocharitetum multicaulis Tüxen 1937 p.p.; Juncusfluitans-Lobelia dortmanna and Lobelia dortmanna associations Spence 1964; Littorella uniflora-Lobelia dortmanna Association Birks 1973; Eriocaulo-Lobelie turn Br.-Bl. & Tx. 1952 sensu Birse 1984.

Constant species

Littorella uniflora, Lobelia dortmanna.

Rare species

Elatine hexandra, Eleocharis acicularis, Eriocaulon septangulare, Isoetes setacea, Subularia aquatica.

Physiognomy

The Littorella uniflora-Lobelia dortmanna community comprises open or closed swards of submerged or temporarily emergent vegetation, usually less than 10 cm tall, dominated by gregarious rosette plants with linear or subulate leaves. The commonest of these is Littorella uniflora, particularly obvious in younger stands and in shallower, wave-churned waters, sometimes sparsely scattered over stony ground, but often dominant in fine densely-packed lawns. Lobelia dortmanna is the only other constant and it, too, can grow in quite luxuriant profusion here, frequently exceeding Littorella in more sheltered, somewhat deeper waters, and revealing its presence in mid-summer with its emergent racemes of attractive lilac flowers. It is, though, not so widely distributed geographically as Littorella and is altogether absent from those fragmentary stands of the community found in southern England.

Also quite common throughout the range of this vegetation is Juncus bulbosus, often occurring in its freefloating form and sometimes forming thick tangles of slender shoots, but no other associate is frequent overall. Thus, there are occasionally some emergent shoots of Carex rostrata, Equisetum fluviatile and, in shallower waters, Eleocharis palustris and the more local E. multicaulis, but increased frequency and cover of these plants usually marks a shift to swamp vegetation. Likewise, there can be some Myriophyllum alterniflorum but this is strongly associated with stands in deeper and less turbulent waters, where the occasional presence of Isoetes lacustris or, more locally, I. setacea marks a transition to the zone in which these quillworts become dominant.

Other plants which occur sparsely through the community are Scirpusfluitans, which is often difficult to see when floating among masses of J. bulbosus, and Baldellia ranunculoides, the emergent leaves of which often get abraded by wave action.