Synonymy

Asteretum and Creek Asteretum Chapman 1934; Aster tripolium var. discoideus nodum Adam 1976; descriptions of Great Aster marsh, Scolt Head, Norfolk.

Constant species

Aster tripolium var. discoideus, Puccinellia maritima, Salicornia agg.

Rare species

Arthrocnemum perenne.

Physiognomy

The association is dominated by the rayless Aster tripolium var. discoideus which is especially distinctive in the late summer–early autumn flowering season when its stems may attain a height of about 1 m; at other times the vegetation is 10–20 cm tall. The stands are generally rather species-poor though there is usually some Salicornia agg., Puccinellia maritima and Suaeda maritima. The substrate surface is frequently dissected by small drainage runnels threading between the A. tripolium rootstocks and locally may be carpeted by free-living fucoids, mainly Fucus vesiculosus ecad caespitosus and Pelvetia canaliculata ecad libera.

Although there is a floristic gradation between lowlevel stands with abundant Salicornia agg. and those at higher levels with abundant Puccinellia maritima, no sensible subdivisions can be made within the association. The floristic disinctions catalogued by Chapman (1934) between a low-marsh Asteretum and a Creek Asteretum are not borne out in the samples.

Habitat

The association occurs as an extensive zone in the low marsh or on creek sides at varying levels in the marsh. At its lower limits, the association seems able to tolerate upwards of 500 submergences/year (Chapman 1960a) with a maximum development around 350 submergences/year (Clapham et al. 1942).