Synonymy

Equisetum limosum reedswamp Rankin 1911; Equisetum fluviatile reedswamp Tansley 1939; Scirpeto-Phragmitetum medioeuropaeum (Koch 1926) R.Tx. & Preising 1942 p.p.

Constant species

Equisetum fluviatile.

Rare species

Calamagrostis stricta, Lysimachia thyrsiflora.

Physiognomy

The Equisetetum fluviatile comprises open or closed vegetation up to about 50 cm high in which Equisetum fluviatile is generally the most abundant species. No other species is frequent throughout, although in each of the sub-communities some of the associates may be locally abundant and their prominence is often emphasised by the thin shoots of the ‘dominant’.

Sub-communities

Equisetum fluviatile sub-community: Open Equisetum fluviatile sociation Spence 1964; Sociatie van Equisetum fluviatile Westhoff & den Held 1969. Here are included pure and very species-poor stands in which E. fluviatile is overwhelmingly the most abundant species. Occasionals include species of periodically inundated finer sediments such as Polygonum hydropiper and Rorippa islandica and, around Scottish lakes, Littorella uniflora has been reported as a common associate of this kind of vegetation (Spence 1964).

Carex rostrata sub-community. In the richer vegetation of this sub-community the shoots of E. fluviatile occur intermixed with tufts of C. rostrata, although the former is always the more abundant. Menyanthes trifoliata and Potentilla palustris are constant as an understorey and, on occasion, may dominate. Within this mat, which sometimes occurs as a swinging semi-submerged vegetation, there may be scattered plants of Galium palustre, Epilobiumpalustre and Eriophorum angustifolium. Calamagrostis stricta and Lysimachia thyrsiflora have been recorded here.

Habitat

Both sub-communities can occur in similar situations to the Caricetum rostratae, being found in shallow to moderately deep, eutrophic to oligotrophic, standing waters in both lowland and upland lakes and pools. Here, the water can be up to more than 1 m deep with a sediment pH of 5.2-6.4. The Equisetetum, however, seems to be as characteristic of silty and sandy substrates as of peaty deposits and the Equisetum sub-community occurs in habitats where the Caricetum rostratae is very rarely found: on fine inorganic material around the draw-down zone of reservoirs and the inundated margins of lowland pools and very slack reaches of highorder streams.

Zonation and succession

In open-water transitions of larger lakes, especially where nutrient-poor waters occur over organic substrates, the community occurs in similar zonations to those involving the Caricetum rostratae and it commonly grades laterally to that community with a switch in dominance to C. rostrata.