Constant species

Bilderdykia convolvulus, Elymus repens, Matricaria perforata, Papaver rhoeas, Polygonum aviculare, Silene noctiflora, Stellaria media, Veronica persica.

Rare species

Silene noctiflora.

Physiognomy

The Papaveri-Sileneetum is an annual community in which Stellaria media, Matricaria perforata and Polygonum aviculare usually provide the bulk of the herbage, along with small ephemerals like Veronica persica, V. polita, Anagallis arvensis, twines of Bilderdykia convolvulus and young shoots of Elymus repens. The most striking feature, however, is the constancy of Papaver rhoeas and the nationally scarce Silene noctiflora, a plant whose peak of flowering is in mid-summer when the distinctive blooms, their yellow-backed petals inrolled until the cool of the evening, are seen most prolifically among cereal stubble or autumn-harvested crops.

Other frequent plants of this kind of vegetation are Chenopodium album, Agrostis stolonifera and Galium aparine with many occasionals including Fumaria officinalis ssp. wirtgenii, Viola arvensis, Aethusa cynapium and Linaria vulgaris.

Habitat

The Papaveri-Sileneetum is confined to light, well drained calcareous soils, mostly among cereals, across the warmer and drier south-east of England.

The most distinctive plant of this assemblage, S. noctiflora, has a more or less Continental distribution in Europe, rare in both the Mediterranean and Scandinavia, preferring better-drained soils and reproducing poorly in wet years (Stewart et al. 1994). With us, it has a marked south-easterly range, extending from Dorset to the Scottish border, where the climate is more congenial for its survival and where calcareous bedrocks are especially extensive.