Synonymy

Fen Formation Tansley 1911 p.p.-, Scirpo-Phragmitetum Koch 1926 p.p.; Valley fen communities Bellamy & Rose 1961 p.p.; Phragmites valley fen Haslam 1965; Angelico-Phragmitetum australis Wheeler 1980a, not sensu Ratcliffe & Hattey 1982.

Constant species

Eupatorium cannabinum, Galium palustre, Phragmites australis.

Rare species

Thelypteris palustris.

Physiognomy

The most consistent feature of the rather variable vegetation included in this community is the prominence of tall herbaceous dicotyledons among which Eupatorium cannabinum, Angelica sylvestris, Lythrum salicaria, Cirsium palustre, Valeriana officinalis, Iris pseudacorus, Filipendula ulmaria and Epilobium hirsutum are the most frequent throughout. Those other tall herbs so characteristic of the Peucedano-Phragmitetum, Peucedanum palustre and Lysimachia vulgaris, are rare and the patchy dominance of more nutrient-demanding species typical of the Phragmites-Urtica fen is uncommon. Here, a variety of monocotyledons may be dominant. Phragmites australis is constant throughout and is often the most abundant species, but, in some stands, Carex paniculata or Cladium mariscus dominate and, more rarely, Carex elata, C. riparia or C. acuta may attain prominence.

Beneath, there is often some Juncus subnodulosus, although the amount of this is very variable, and a variety of small herbs, among which Mentha aquatica and Caltha palustris are the most frequent. Galium palustre is a constant sprawler with, less commonly, Vicia cracca, Solanum dulcamara and Calystegia sepium. Bryophytes are rarely abundant but there is occasionally a little Calliergon cuspidatum and Brachythecium rutabu-lum. In some sub-communities, saplings of Salix cinerea or Myrica gale bushes are conspicuous.

Sub-communities

Phragmites australis sub-community: Angelico-Phragmitetum typicum and juncetosum subnodulosi Wheeler 1980tz. Here, Phragmites is usually the dominant, forming a canopy 1-2 m tall, although E. cannabinum and E. hirsutum can both be locally abundant. Denser stands of reed are rather species-poor but where the cover is more open there are small amounts of the tall and short herbaceous dicotyledons of the community and frequently a little J. subnodulosus. Here, too, Lychnis floscuculi, Equisetum fluviatile and E. palustre occurs occasionally and sprawlers are sometimes conspicuous with Vicia cracca, Calystegia sepium, Galium uliginosum and Lotus uliginosus. Calliergon cuspidatum and Brachythecium rutabulum may be prominent over litter and damp patches of bare substrate.