Constant species

Spartina townsendii sensu lato comprises the male sterile F1 hybrid S. × townsendii and the much commoner fertile amphidiploid from the same cross, S. anglica. The latter alone was recorded in our samples and is the sole constant of the community.

Rare species

Arthrocnemum perenne

Physiognomy

S. anglica always dominates as scattered tussocks, coalescing clumps or a continuous sward up to 1 m in height. The community is species-poor though the associates are somewhat varied. Puccinellia maritima and annual Salicornias occur frequently and may account for up to 50% cover and beneath them there is often an algal mat. Free-living fucoids such as Fucus vesiculosus ecad caespitosus and ecad volubilis may be locally abundant. S. × townsendii may be recognised within S. anglica swards by its denser tussocks of shorter shoots. It sometimes forms extensive swards as at Hythe and Poole (Marchant 1967) and may occur as a landward fringe to S. anglica (Hubbard 1965). In such cases the associates of S. × townsendii are the same as in the community as a whole.

Sub-communities

Beeftink & Géhu (1973) and Kortekaas et al. (1976) have characterised a variety of sub-communities within the European Spartinetum townsendii. Some corresponding distinction could be made within the British stands but their general species poverty, their capacity for rapid floristic change and the unchallenged dominance of S. anglica throughout argue for retaining a single community at national level.