Synonymy

Fen carr Pallis 1911, Godwin & Turner 1933, Godwin 1936, Tansley 1939, Lambert 1951; Closed carr Pearsall 1918 p.p.; Rhamnetum, Franguletum, Rhamno-franguletum Godwin & Tansley 1929, Godwin 1936, 1943a, b; Betuletum Godwin & Turner 1933; Semiswamp and pseudo-swamp carrs Lambert 1951 p.p.; Calamagrostis sere Poore 1956bp.p.; Alder woodland type 2c McVean 1956bp.p.; Betulo-Dry opter ide turn cristatae Wheeler 1978; Osmundo-Alnetum (Klötzli 1970) Wheeler 1980c p.p.; Frangula alnus and Rhamnus catharticus sociations Wheeler 1980c p.p.; Betulo-Myricetum gale Wheeler 1980c p.p.; Alnus-Salix-Betula woodland Meres Report 1980 p.p.; Fen Woodland Fitter et al. 1980 p.p.

Constant species

Betula pubescens, Salix cinerea, Phragmites australis.

Rare species

Carex elongata, Dryopteris cristata, D. x uliginosa, Peucedanum palustre, Pyrola rotundifolia, Thelypteris palustris.

Physiognomy

The Salix cinerea-Betula pubescens-Phragmites australis woodland is rather variable in the floristics and physiognomy of its woody component. Salix cinerea and Betula pubescens are the most frequent species throughout and, together with some Alnus glutinosa, they usually form the bulk of the canopy. These major colonists show some differences in their preference for the various habitat conditions characteristic of the community (see below) but the chance availability of seed-parents and vagaries of propagule dispersal clearly play a large part in determining the composition and structure of the canopy, especially in the early stage of development (e.g. Godwin 1936). Moreover, these species show some ability to ‘leapfrog’ over one another in the colonisation process, so that, though S. cinerea is a common early invader (e.g. Pearsall 1918, Lambert 1946), it may be overtaken by waves of Alnus (e.g. Pigott & Wilson 1978) or B. pubescens. Without extensive detailed studies on a large number of sites, it is difficult to say whether there are consistent sequences of invasion which are reflected in the subsequent woodland structure. Young canopies of this community are certainly very heterogeneous internally and very different, one from another, comprising mixtures of these three species in various proportions, with individuals of different ages, forming a cover that varies from low, open scrub or very dense thickets to taller woodland with some stratification (e.g. Pallis 1911, Godwin & Turner 1933, Lambert 1951).