British Plant Communities

Constant species

Poa annua, Senecio vulgaris.

Physiognomy

The Poa annua-Senecio vulgaris community brings together a variety of weed assemblages which are distinctive in their combinations of common species rather than by the presence of striking differentials. Poa annua and Senecio vulgaris are the only constants throughout but Lolium perenne is very frequent and Capsella bursa pastoris and Cerastium fontanum occur commonly in various sub-communities. Occasionals include Cirsium arvense, Plantago major, Poa trivialis, Veronica persica and Urtica dioica. The assemblages vary in their total cover and, though most of the more frequent species here are emphemeral, a perennial grassy element can be seen establishing in some sub-communities.

Sub-communities

Polygonum persicaria-Ranunculus repens sub-community. The abundance of knotweeds and spurges is often the most striking feature here, with Polygonum aviculare and, more strongly preferential, P. persicaria both constant, Euphorbia helioscopa and E. exigua frequent. Stellaria media is also more common in this sub-community than elsewhere with Ranunculus repens, Anagallis arvensis, Viola arvensis, Bilderdykia convolvulus, Anthemis cotula, Trifolium repens and Lapsana communis. Preferential occasionals include Sinapis arvensis, Raphanus raphanistrum, Spergularia arvensis and Fumaria officinalis.

Polygonum aviculare-Matricaria perforata sub-community. P. aviculare remains constant here with P. persicaria and P. arenastrum occasional, but more striking is the high frequency and often abundance of mayweeds: Chamomilla suaveolens, C. recutita and M. perforata are all common in this sub-community. Chenopodium album and Coronopus squarratus are also weakly preferential.