Constant species

Anagallis arvensis, Bilderdykia convolvulus, Polygonum aviculare, Veronica persica.

Rare species

Ajuga chamaepitys, Scandix pecten-veneris.

Physiognomy

The Kickxietum spuriae comprises annual vegetation that is usually dominated by smaller ephemerals like Anagallis arvensis, Veronica persica and Polygonum aviculare with twining trails of Bilderdykia convovlulus. However, by mid- to late summer, the most distinctive feature in many stands is the presence of one or other, often both, of Kickxia elatine and K. spuria, their downy shoots spreading among the cereal stubble that usually forms the habitat of this vegetation. Euphorbia exigua is another summer annual that occurs more or less frequently throughout.

Less distinctive but still common through the community as a whole are Poa annua, Matricaria perforata, Sonchus asper, Myosotis arvensis, Elymus repens and Plantago major, with Veronica polita, Lapsana communis, Papaver rhoeas, Cirsium arvense, Galium aparine and Lolium perenne occasional.

Sub-communities

Stellaria media-Convolvulus arvensis sub-community: Kickxietum spuriae Kruseman & Vlieger 1939; unassigned aufnahmen sensu Silverside 1977. The two Kickxia spp. and E. exigua are frequent here but are accompanied by less distinctive weeds like Stellaria media and tangles of Convolvulus arvensis. The grasses Avena fatua, Alopecurus myosuroides and Agrostis stolonifera are quite common, the inflorescences of the first two often growing up among the cereal crop. Aethusa cynapium, Chenopodium album and Anthemis cotula are occasional.

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.

Constant species

Anchusa arvensis, Bilderdykia convolvulus, Chenopodium album, Descurainia sophia, Elymus repens, Polygonum aviculare, Reseda lutea.

Physiognomy

The Descurainio-Anchusetum is an ephemeral community in which Descurainia sophia, probably a long-established introduction (Rich 1991), Anchusa arvensis and Reseda lutea comprise a distinctive group of constants, along with very frequent Elymus repens, Chenopodium album, Polygonum aviculare and Bilderdykia convolvulus.

Also very common are Veronica persica, V. polita, Chamomilla suaveolens, Matricaria perforata, Stellaria media, Senecio vulgaris, Solanum nigrum, Silene alba and Colvolvulus arvensis. More distinctive occasional include Erodium cicutarium, Conyza canadensis, Urtica urens, Papaver rhoeas and Linaria vulgaris with the grasses Poa annua, Agrostis capillaris, A. stolonifera and Dactylis glomerata.

Habitat

The Descurainio-Anchusetum is characteristic of disturbed, dry, sandy soils among arable crops in the Continental climate of East Anglia.

D. sophia is perhaps not native to Britain (Rich 1991, Stace 1995) but it is long established and was formerly, according to Salisbury (1964), much more common than now as a plant of waste ground. It remains frequent among arable crops in East Anglia from where Silverside (1977) characterised this assemblage on soils derived from superficials over chalk, reasonably calcareous, often sandy, though not always rapidly draining. Even in the very dry climate of Breckland, where the community was especially distinctive, the soils could be moist, particularly where irrigation was frequent. Anchusa arvensis, Reseda lutea and Veronica polita are three other species here which reflect the combination of light soils in a more Continental climate typical of the community.

Synonymy

Dune grassland Pearsall 1934; Dune pasture Gimingham 1964a p.p.; Astragalo-Festucetum arenariae Birse 1980 p.p.

Constant species

Agrostis capillaris, Ammophila arenaria, Carex arenaria, Festuca ovina, Poa pratensis.

Rare species

Astragalus danicus.

Physiognomy

The Carex arenaria-Festuca ovina-Agrostis capillaris community comprises short, generally closed swards dominated by various mixtures of Carex arenaria and a number of grasses, of which Festuca ovina, Agrostis capillaris and Poa pratensis s. l. are the most frequent and abundant. F. rubra also occurs quite commonly, and Anthoxanthum odoratum, Luzula campestris and Holcus lanatus are variously represented in the different sub-communities, with Koeleria macrantha occasional. Ammophila arenaria persists at high frequency, too, though it hardly ever shows any vigour, being usually reduced to sparse and debilitated shoots.

Dicotyledonous herbs are rather few in number, but the assemblage is distinctive, with Galium saxatile, Lotus corniculatus, Galium verum, Cerastium fontanum and Rumex acetosella occasional to frequent throughout. In some stands, Hypochoeris radicata, Thymus praecox and Hieracium pilosella become more common, with Campanula rotundifolia, Viola riviniana and Achillea millefolium occurring more often in others. Compared with more open dune swards, however, ephemeral plants are noticeably scarce. There are very occasionally some scattered bushes of Calluna vulgaris, frequently nibbled down, but any increase in the cover of ericoid sub-shrubs usually marks a transition to heath.

Bryophytes are fairly numerous and sometimes abundant in the sward and, though Dicranum scoparium is very common, it is bigger pleurocarps that are generally more obvious, with frequent records for Rhytidiadelphus squarrosus, Pseudoscleropodium purum, Hylocomium splendens and Pleurozium schreberi and more occasional occurrences of Rhytidiadelphus triquetrus and Hypnum cupressiforme.

Constant species

Parietaria diffusa.

Rare species

Brassica oleracea, Draba aizoides, Silene nutans.

Physiognomy

The Parietarietum judaicae comprises vegetation of crevices and small ledges in which Parietaria diffusa is the only consistent feature throughout, with occasional trails of Hedera helix and Galium aparine. Asplenium ruta-muraria is a scarce associate.

Sub-communities

Homalothedum sericeum-Tortula muralis sub-community. Parietaria tends to be more abundant in this vegetation and the only frequent associates are H. sericeum, T. muralis, Schistidium apocarpum and Barbula spp. Occasionally, there are records for small asplenioid ferns, including A. trichomanes, A. adiantum-nigrum, Poa trivialis and ephemerals such as Bromus hordeaceus hordeaceus, B. sterilis and Arabidopsis thaliana.

Daucus carota sub-community. Parietaria is generally of lower cover here and is often accompanied by clumps of Dactylis glomerata and Festuca rubra, tall herbs such as Daucus carota, Centaurea scabiosa and Euphorbia portlandica with occasional Plantago lanceolata, P. coronopus, Sanguisorba minor, Beta vulgaris ssp. maritima and Sedum acre. This vegetation also provides a locus for the nationally rare Brassica oleracea and, more locally, Draba aizoides and Silene nutans.

Habitat

The Parietarietum is characteristic of sunnier crevices and ledges in walls and on rock faces in quarries and natural cliffs in the warmer and drier southern lowlands of Britain. Parietaria is a somewhat calcicolous plant with a more or less Continental distribution in Britain, being commonest in the south-east of England and extending north and west around the coast (Perring & Walters 1962).

Constant species

Agrostis stolonifera, Ranunculus repens.

Physiognomy

The Agrostio-Ranunculetum comprises open or closed vegetation in which a mat of stolons and runners of A. stolonifera and R. repens is the characteristic consistent feature. Throughout the community as a whole, no other species is frequent but there is occasionally some Poa trivialis and Trifolium repens in the ground carpet and scattered shoots or small clumps of Urtica dioica and Cirsium arvense. Senecio vulgaris, Atriplex prostrata and Taraxacum officinale agg. are scarce companions.

Sub-communities

Polygonum hydropiper-Rorippa sylvestris sub-community. The cover of the two community constants tends to be higher here and there are occasionally quite conspicuous shoots of Phalaris arundinacea and Juncus effusus with scattered plants or little patches of Polygonum hydropiper and Rorippa sylvestris springing up among the perennials. Galium palustre, Mentha aquatica, Myosotis scorpioides and Alopecurus geniculatus are occasionally seen.

Poa annua-Polygonum aviculare sub-community: Ranunculetum repentis Knapp 1946 sensu Silverside 1990. Poa annua is a constant and sometimes abundant contributor to the ground carpet in this sub-community with frequent records too for Plantago major, Stellaria media, Polygonum aviculare, P. persicaria and Chamomilla suaveolens. Lolium perenne, Elymus repens, Potentilla anserina and Anagallis arvensis occur occasionally and there are quite often small patches of mosses on bare areas of damp soil: Bryum rubens, Pottia truncata and Dicranella staphylina are the most consistent contributors to this element of the vegetation.

Synonymy

Teesdalio-Arnoseridetum minimae (Malcuit 1929 R.Tx. (1937) 1950 sensu Silverside 1977

Constant species

Aphanes microcarpa, Poa annua, Rumex acetosella, Viola arvensis.

Rare species

Anthoxanthum aristatum, Briza minor.

Physiognomy

Both Viola arvensis and Aphanes microcarpa are constants in the open annual vegetation of the Viola-Aphanes community, although Poa annua often contributes much of the cover by early summer. The diminutive perennial herb Rumex acetosella is very frequent too, producing its annual tufts of shoots in the gaps among the other plants.

Frequent associates, usually at low cover, include Matricaria perforata, Stellaria media, Veronica arvensis and Polygonum aviculare with Bilderdykia convolvulus, Trifolium dubium, Spergula arvensis, Ornithopus perpusillus, Viola tricolor, Chrysanthemum segetum, Alopecurus myosuroides, Scleranthus annuus and Anagallis arvensis among the more common occasionals. This community also provides a locus for the introduced grass, Anthoxanthum aristatum, originally from the Mediterranean and spreading widely in southern England in the nineteenth century but now extremely rare (Salisbury 1964, Perring & Farrell (1977). Briza minor, another national rarity, has also been recorded here but it is more usually found now in other communities.

Areas of bare ground can have scattered plants of acrocarpous mosses such as Bryum microerythrocarpum, B. rubens, Dicranella staphylina, Ceratodon purpureus, Phascum cuspidatum and Pleuridium subulatum.

Habitat

The Viola-Aphanes community is typically found among arable crops on impoverished base-poor sandy soils in the more Continental eastern parts of Britain. The local occurrence of suitable soils and the prevalence of intensive cereal production make this a very scarce vegetation type now.

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.

Constant species

Anagallis arvensis, Medicago lupulina, Papaver rhoeas, Poa annua, Polygonum aviculare, Veronica persica, Viola arvensis.

Rare species

Veronica triphyllos.

Physiognomy

The Papaveretum argemones comprises annual weed vegetation in which the most striking feature is the abundance of various species of red poppy. Papaver rhoeas is the most frequent and usually the most abundant of these, its bright scarlet flowers appearing from mid-June and continuing intermittently until October, but also common, particularly in the south and east of Britain and beginning to flower earlier, is P. argemone. A third species, like P. argemone in its smaller and paler scarlet flowers, though more widespread, is P. dubium.

Other frequent contributors to the more or less open cover of this vegetation are Viola arvensis, Veronica persica, V. arvensis, Anagallis arvensis, Poa annua, Medicago lupulina, Polygonum aviculare, Bilderdykia convolvulus, Capsella bursa-pastoris and Trifolium repens. Elymus repens and Agrostis stolonifera are common, too, and can be locally abundant.

Occasional in the Papaveretum include Arenaria serpyllifolia (with some plants distinguished as ssp. leptoclados), Galium aparine, Myosotis arvensis, Chenopodium album, Matricaria perforata, Chamomilla suaveolens, Sonchus asper, S. oleraceus and Senecio vulgaris. The nationally rare Veronica triphyllos has also been recorded in this vegetation.

Habitat

The Papaveretum is characteristic of disturbed, light and friable soils that are not too calcareous, throughout the warmer and drier lowlands of Britain and it is especially frequent in cereal fields that have escaped herbicide treatment.

Constant species

Arrhenatherum elatius, Festuca rubralovina, Geranium robertianum, Gymnocarpium robertianum, Teucrium scorodonia, Ctenidium molluscum.

Physiognomy

The Gymnocarpietum robertiani comprises more or less open stands of fern- and grass-dominated vegetation disposed over the distinctive topography of limestone screes and pavement. Scattered fronds of Gymnocarpium, arising separately from the creeping rhizomes, begin to emerge rapidly in late spring, their rather stately forms attaining up to 40 cm or so in height. Among these, occasionally in some abundance, are loose tussocks of Arrhenatherum and, less commonly, Festuca ovinalrubra (not distinguished in available data) and Brachypodium sylvaticum. In sunnier situations, which the fern seems to tolerate well, perhaps because of its somewhat mealy surface (Page 1982), the Brachypodium often has a rather lurid yellow-green tinge. Sesleria albicans does not appear in the table because samples of the community were not collected within the range of this grass but it can figure prominently in this vegetation in the Yorkshire Dales and southern part of the Lake District.

Other very frequent components are Geranium robertianum, commonly showing a reddish hue to its stems with the typically impoverished nature of the substrate, Teucrium scorodonia, Mycelis muralis and Mercurialis perennis. Where clonal patches of the last plant thicken up, the Gymnocarpium seems to suffer and be gradually eclipsed (Page 1982). Less common vascular associates include Origanum vulgare, Carex flacca, Viola riviniana, Senecio jacobaea, Oxalis acetosella, Arabis hirsuta and, in the northern Pennines, Galium sterneri.

Synonymy

Elymetum repentis maritimum, Elymus repens, Potentilla anserina-Elymus repens-Vicia and Elymus repens-Potentilla anserina soziations? Nordhagen 1940.

Constant species

Agrostis stolonifera, Atriplex prostrata, Elymus repens, Festuca rubra.

Rare species

Allium scorodoprasum, Hordeum marinum.

Physiognomy

The Elymetum repentis has a closed grassy sward up to about 1 m tall, generally dominated by Elymus repens with usually smaller amounts of Festuca rubra and Agrostis stolonifera and, beneath, scattered plants of Atriplex prostrata and an open ground cover of Potentilla anserina. Oenanthe lachenalii, Sonchus arvensis, Rumex crispus and Cirsium arvense are occasional and often give a scruffy appearance to the vegetation and tussocks of Juncus gerardii or Festuca arundinacea may be locally prominent. The community is generally richer and more varied than the Atriplici-Elymetum with a wide range of occasionals of low frequency, some characteristic of other disturbed upper-marsh vegetation of strand-lines and reclamation banks, others more typical of rank inland grasslands. Allium scorodoprasum has been recorded in vegetation of this kind on the north Solway coast and Hordeum marinum from Somerset. Bryophytes occur occasionally with Eurhynchium praelongum, Amblystegium riparium, Funaria hygrometrica, Pottia heimii and Bryum spp.

Habitat

The community is characteristic of similar situations to those occupied by the Atriplici-Elymetum: upper-marsh areas where there is often a combination of disturbance, drift-litter deposition and some freshwater influence. It is, however, less consistently confined to well-drained sites, occasionally growing on heavy waterlogged clays.

Synonymy

Suaedetum fruticosae Tansley 1939 p.p.; Agropyro-Suaedetum fruticosae Adam 1976; Halimiono-Suaedetum fruticosae Adam 1976.

Constant species

Halimione portulacoides, Suaeda vera.

Rare species

Arthrocnemum perenne, Suaeda vera.

Physiognomy

The Elymo pycnanthi-Suaedetum verae is of variable appearance. The two association constants are sometimes co-dominant as a more or less closed shrubby cover; in other cases they occur as scattered bushes in a grassy ground. The S. vera shoots provide a niche for a varied flora of epiphytic lichens (Ellis 1960).

Sub-communities

Elymus pycnanthus sub-community: Elymo pycnanthi-Suaedetum verae typicum Géhu & Delzenne 1975; Agropyro-Suaedetum fruticosae Adam 1976. Here the cover of H. portulacoides is low and the vegetation is dominated by complementary proportions of S. vera bushes and stiff clumps of Elymus pycnanthus with usually a little Festuca rubra. The upper edge of stands may be marked in spring by a narrow band of winter annuals such as Cochlearia danica, Myosotis ramosissima, Sagina maritima and Valerianella locusta germinating on drift debris.

Halimione portulacoides sub-community: Elymo pycnanthi-Suaedetum verae halimionetosum Géhu & Delzenne 1975; Halimiono-Suaedetum fruticosae Adam 1976. S. vera and H. portulacoides are co-dominant as a shrubby canopy of variable height over a ground of scattered Puccinellia maritima and Limonium cf. vulgare, often with a little Aster tripolium, annual Salicornia spp., Spergularia media and Suaeda maritima. The sub-community provides an occasional high-level context for Bostrychia scorpioides and Pelvetia canaliculata.

Synonymy

Spergulo-Chrysanthemetum (Br.-Bl. de Leeuw 1936) R.Tx. 1937 sensu Silverside 1911 p.p.; Medicagi-Ranunculetum parviflori Silverside 1977 p.p.

Constant species

Anagallis arvensis, Cerastium glomeratum, Fumaria muralis ssp. boraei, Juncus bufonius, Poa annua, Senecio vulgaris, Sonchus asper.

Rare species

Allium babingtonii, Briza minor, Fumaria bastardii, Silene gallica.

Physiognomy

The Cerastium glomeratum-Fumaria muralis ssp. boraei community is one of the British weed assemblages in which fumitories figure with some prominence. F. muralis ssp. boraei is the most common taxon here and it can be abundant. Less frequent in the community, though locally prominent, are F. officinalis (a plant with a wider distribution nationally than F. muralis ssp. boraei), and the nationally scarce F. bastardii and F. occidentalis.

Other distinctive constants of this kind of vegetation are Cerastium glomeratum and Juncus bufonius with Anagallis arvensis, Poa annua, Senecio vulgaris and Sonchus asper. P. trivialis and Coronopus didymus are among the frequent associates but more striking is the common occurrence of Chrysanthemum segetum and the nationally rare or scarce Ranunculus parviflorus, Briza minor and Silene gallica. Gladiolus byzantinus is a common escape from the bulb crops among which this assemblage is often found.

Occasionals include Veronica persica, Medicago arabica and Rumex acetosella with the South African introduction Oxalis pes-caprae naturalised here, though with varying frequency in the different sub-communities, and another introduced sorrel O. corniculata occurring much more rarely.

Synonymy

Lythrum hyssopifolia stands Preston & Whitehouse 1986.

Constant species

Anagallis arvensis, Juncus bufonius, Lythrum hyssopifolia, Matricaria perforata, Plantago major, Polygonum aviculare, Polygonum persicaria, Bryum klinggraeffii, Pottia starkeana ssp. minutula, Riccia glauca.

Rare species

Lythrum hyssopifolia.

Physiognomy

The Lythrum hyssopifolia-Juncus bufonis community comprises ephemeral vegetation which, by mid-summer, is typically dominated by mixtures of the nationally rare Lythrum hyssopifolia, together with Juncus bufonius, Plantago major (diagnosed as ssp. intermedia by Preston & Whitehouse 1986), Polygonum persicaria and P. aviculare. Also frequent throughout among the vascular associates are Mentha arvensis, Rumex crispus and seedlings of Salix spp. Elymus repens is occasional and, in sites which have been undisturbed by recent ploughing, Polygonum amphibium tends to increase. Bryophytes are an important element in the vegetation with Bryum kling graeffii and Riccia glauca common throughout, the former with modest abundance.

Preston & Whitehouse (1986) noted a consistent, but overlapping, contrast between the stands they sampled but not sufficiently sharp to characterise sub-communities. To one extreme, species such as Anagallis arvensis, Alopecurus myosuroides, Kickxia elatine, K. spuria and more obviously Anthemis cotula and Aethusa cynapium ssp. agrestis, tended to be associated with Pottia starkeana ssp. minutula, Barbula unguiculata, B. argenteum, Dicranella staphylina and D. varia. To the other, Matricaria perforata and Equisetum arvense were found with Physcomitrella patens, Riccia cavernosa, R. subbifurca and Pohlia carnea.

Constant species

Several distinct taxa can be recognised among the British annual Salicornias but diagnosis below the level of the three groups S. europaea, S. procumbens and S. pusilla is difficult for non-specialists. Here, all annual taxa encountered are described under Salicornia agg. and this is the sole constant of the community.

Rare species

Arthrocnemum perenne.

Physiognomy

The community comprises ephemeral stands of annual Salicornias sometimes with no other species. The vegetation is invariably somewhat open and though Salicornia agg. is always conspicuous, the density of plants is variable: around The Wash, for example, Salicornia agg. cover is high whereas at sites with sandier substrates the density can be very low. There is often an algal mat over the substrate surface but vascular companions are usually very few. Scattered plants of Puccinellia maritima, Suaeda maritima and Spartina anglica occur frequently with occasional records for a variety of other lower marsh species. At a few sites (Blakeney Point, for example), Fucus vesiculosus ecad caespitosus is abundant.

Sub-communities

With careful identification of distinct taxa, it may be possible to define a range of communities within this broad general unit as a number of Continental authors have done (see, for example, Géhu & Delzenne 1975). Ball & Tutin (1959) recommend collecting a dozen specimens from populations in September/October when the characteristic colours have developed.

The sampling of weed vegetation and other assemblages of open habitats

In the days before political correctness was an issue, the editors of a renowned book on weeds made the memorable observation that, as a class, weeds had ‘much in common with criminals’: that is, when not engaged in nefarious activities, they were often admirable. Certainly, that book (Salisbury 1964), then and still the most accessible account of these plants, did much to inform and engage, and it grouped weeds into broad ecological categories according to habitat – cornfield and arable weeds, grassland weeds, weeds of sandy soils, of chalk, of roadsides and wastes, and of gardens. This was scarcely a classification, of course, but it was a considerable advance on Tansley (1939) which, like its predecessor (Tansley 1911), made only fleeting references to weed vegetation of any kind, and then usually within the context of successions to other plant communities. In fact, Salisbury himself (1964) was building on previous work, like the survey of Buckman (1856), who described arable weeds of different soil types, and the studies of Brenchley (1911, 1912, 1913), who made more comprehensive field lists in various localities, noting the geology, soils and crops with which the plants were associated.

Synonymy

Dune grassland Gimingham 1964a.

Constant species

Achillea millefolium, Ammophila arenaria, Arrhenatherum elatius, Festuca rubra, Poa pratensis.

Rare species

Acaena novae-zelandiae, Astragalus danicus.

Physiognomy

The Ammophila arenaria-Arrhenatherum elatius grassland includes rank, tussocky swards in which both Festuca rubra and Ammophila remain very common, the former especially being often abundant, indeed the most frequent dominant overall, the latter rather more patchily represented, but plentiful and vigorous in some stands. Compared with other dune grasslands, however, a noticeable difference here is the common occurrence of Arrhenatherum elatius, often growing in some abundance and quite frequently co-dominant. Other grasses figure, too, though their contribution to the cover is generally small. Poa pratensis agg. (probably P. subcaerulea in many cases) is constant in small amounts, for example, and Dactylis glomerata is often found, though only exceptionally with any abundance. More occasionally, there can be some Holcus lanatus, Trisetum flavescens, Elymus pycnanthus, E. farctus and E. repens, but smaller species like Koeleria macrantha, Agrostis capillaris and Anthoxanthum odoratum tend to be very scarce. Carex arenaria is only moderately common, and Luzula campestris rather infrequent.

Quite a variety of dicotyledonous herbs occur in the community, the commonest able to grow up tall through the grasses or form a loose, bushy understorey in more open parts of the sward.

Stands dominated by rayed Aster tripolium have been encountered in situations with some freshwater influence such as brackish ditches behind sea walls where Spartina anglica and Puccinellia maritima are frequent associates. Beeftink (1962, 1965) has described similar vegetation from sites with local freshwater flushing as a distinct Aster tripolium sociatie. Rayed A. tripolium is also abundant on periodically-flooded saline muds in inland salt-marshes with Spergularia marina and Puccinellia distans (see the Puccinellietum distantis asteretosum of Lee 1977; also Edees 1972).

Although some floras note a certain habitat distinction between rayed forms of A. tripolium and the var. discoideus (e.g. Petch & Swann 1968, Jermyn 1974, Gibbons 1975), the situation is far from simple. The var. discoideus can also occur in brackish habitats and Jermy & Crabbe (1978) have recorded vegetation rich in dwarf rayed A. tripolium and Suaeda maritima from Salen Marsh, Mull, where there is little freshwater influence (cf. the intertidal Suaedeto maritimae-Asteretum tripolii Hocquette & Géhu 1965 in Ghestem 1972). Furthermore, even within the rayed form there appears to be a complex of genetically determined variation adapted to different environmental conditions (Gray 1971, 1974; Gray et al. 1979). Further sampling is needed to establish the ecological implications of this variation and to check the validity of erecting separate communities for the different forms.

Constant species

Epilobium angustifolium.

Physiognomy

The Epilobium angustifolium community is overwhelmingly dominated by E. angustifolium, the tall shoots of which can reach well over 1 m by summer. No other species is frequent throughout but the commonest associates overall are Rubus fruticosus agg., Holcus lanatus, Pteridium aquilinum and Urtica dioica with various other species reflecting the different situations in which this kind of vegetation can develop.

Sub-communities

Holcus lanatus-Festuca ovina sub-community. In this grassy or heathy vegetation, E. angustifolium is accompanied by frequent Holcus lanatus and Festuca ovina, occasional Anthoxanthum odoratum, Agrostis capillaris, Potentilla ereeta, Galium saxatile and Teucrium scorodonia, and sometimes by scattered Calluna vulgaris, Erica cinerea, Ulex europaeus and U. gallii and sparse or patchy Pteridium.

Urtica dioica-drsium arvense sub-community. U. dioica is a frequent associate here, though not rivalling E. angustifolium in cover, and there are often scattered individuals of Cirsium arvense and C. vulgare. Holcus lanatus remains common but is occasionally accompanied here by Arrhenatherum elatius, Dactylis glomerata, Holcus mollis, Deschampsia cespitosa and Poa trivialis, with Heracleum sphondylium and Galium aparine. Patches of Rubus fruticosus agg. can sometimes be seen.

Rubus fruticosus agg.-Dryopteris dilatata sub-community. Rubus fruticosus agg. is constant here, along with Dryopteris dilatata, and occasional Pteridium aquilinum and saplings of Betula pendula, B. pubescens, Pinus sylvestris, P. nigra, Quercus robur and Q. petraea. Bryophytes Such as Mnium hornum, Aulacomnium androgynum and Lophocolea bidentata s. l. are sometimes prominent on decaying wood.