Synonymy

Stachys arvensis community Silverside 1977.

Constant species

Anagallis arvensis, Poa annua, Polygonum aviculare, Stachys arvensis.

Rare species

Fumaria bastardii.

Physiognomy

The constancy of Stachys arvensis is the most striking feature of the Poa annua-Stachys community, along with P. annua, Polygonum aviculare and Anagallis arvensis. Also very common throughout the assemblage are Spergula arvensis, Stellaria media, Plantago major, Matricaria perforata, Chamomilla suaveolens, Ranunculus repens, Elymus repens and Agrostis stolonifera. Occasionals include Capsella bursa-pastoris, Bilderdykia convolvulus, Fumaria muralis ssp. boraei, Senecio vulgaris, Taraxacum officinale agg., Trifolium repens, Holcus lanatus and Lolium perenne. The total cover of vascular plants is usually high and some stands have a distinctly grassy appearance. In one sub-community, acrocarpous mosses can be varied and quite abundant.

Sub-communities

Chenopodium album-Euphorbia helioscopa sub-community. Chamomilla suaveolens, Sonchus asper and Veronica persica show somewhat higher frequency than usual here but more striking preferential are Chenopodium album and Euphorbia helioscopa. Knotweeds are quite often prominent with Polygonum lapathifolium, P. nodosum and P. persicaria occasionally joining P. aviculare, and Viola arvensis, Atriplex patula, Sinapis arvensis, Sonchus arvensis, Sherardia arvensis and Agrostis capillaris are all preferential at low frequency. Among nationally-scarce plants, this sub-community occasionally provides a locus for Kickxia elatine and Misopates orontium.

Cerastium fontanum-Bryum rubens sub-community. Polygonum persicaria increases in frequency in his subcommunity but more exclusive preferentials are Cerastium fontanum and a variety of acrocarpous mosses of which Bryum rubens, Pottia truncata and Dicranella staphylina are the most common with B. klinggraeffii and B. violaceum less frequent.