Briza media L

Journal of Ecology

2002

90

, 737–752

© 2002 British Ecological Society

Blackwell Science, Ltd

BIOLOGICAL FLORA OF THE BRITISH ISLES

*

No. 224

List Br. Vasc. Pl. (1958) no.

680

, 1

Briza media

L.

J. M. DIXON

Department of Environmental Science, University of Bradford, Bradford BD7 1DP, UK

A loosely tufted perennial with short rhizomes fromwhich arise vegetative shoots. Culms 15–60 (

−

100) cmhigh, slender, erect, 2–3-noded, solitary, smooth.Leaves with dull glaucous to mid-green adaxial andabaxial surfaces, hairless; blades usually 4–20 (

−

28) cmlong, 2–4 (

−

7) mm wide, with minute acroscopic teethon the margins, with a slender boat-shaped tip; ribsnumerous, closely packed, less obvious on the abaxialsurface; sheaths smooth, entire, soon splitting, darkreddish-brown at base; ligules up to 1.5 mm long,membranous, blunt with irregular margins. Culmleaves 3 or 4, uppermost with long sheaths. Panicles 4–10 (

−

18) cm long, lax, roughly pyramidal, with up to 20branches, and up to 60 spikelets, sparsely divided,spreading, with scabrous hair-like pedicels 5–20 (

−

50)mm long and slightly thickened below the spikelets.Spikelets 4–7 mm long and wide, loosely scattered anddrooping, broadly elliptic to broadly ovate, laterallycompressed, generally purplish-brown, usually break-ing up at maturity beneath the lemmas but many spike-lets remaining undispersed on the branches and shedfrom the panicle intact, 4–9 (

−

12)-flowered. Glumesslightly unequal, deeply concave, hooded at the apex,boat-shaped, 2.5–3.5 mm long, with 3–5 veins, firmlymembranous, dull-purple with white and shiny mar-gins. Lemmas 3.7–4.1 mm, strongly cordate at the base,bluntly keeled in the lower half, closely overlapping,rounded on the back, with 7–9 veins, variegated purpleand green, with hyaline margin. Paleas flat, thin,almost as long as the lemma, with two keels, narrowlywinged. Lodicules 2, linear-lanceolate, acute. Grainenclosed within the papery lemma and palea,

c

. 2 mmlong, rounded on the back, flattened on the front; meanoven-dry weight 0.53 mg. The root system is a densemat of whitish fibrous roots. The primary roots are upto 1 mm in diameter and are largely unbranched, butthere is a dense network of branching secondary roots.The root mass is fairly vertical with an average rootlength of

c

. 40 cm. The species produces pale brownrhizomes up to 13 cm long and 1.5 mm in diameter.

Native. Subspecies

media

occurs throughout therange; subspecies

elatior

(Sibth. & Sm.) Rohlenaoccurs in south-east Europe.

Briza media

is a widely distributed common speciesof dry and calcareous, but also moist and acidic grass-land, of little herbage value.

I.

Geographical and altitudinal distribution

The distribution of

B. media

in the British Isles isshown in Fig. 1. The species is widely distributedthroughout the British Isles on Chalk, Carboniferous,Magnesian and Devonian Limestone, and is also foundon circumneutral soils and on some acid soils wherethese are well-drained. The species is only occasional inthe north of Scotland, the Shetland Isles and OrkneyIsles and on some of the Western Isles. It has beenrecorded from the Isle of Man, the Channel Isles andthe Isle of Wight but not from the Isles of Scilly. InWales the species is common on the Lias of SouthDyfed and on the calcareous substrata in the south ofPowys but occurs less frequently on calcareous sub-strata of Gwent, Gwynedd and Clwyd (Hyde & Wade1957). It is widely distributed across central Ireland,but is less common in both the north and the south ofIreland.

Briza media

is recorded throughout western Europebut is absent from the Faeroe Islands and Iceland, andis noted only as a casual in the extreme north of Europein

Flora Europaea

. It is absent from the Mediterraneanislands of the Balearics, Crete, Sicily and Cyprus, anddoes not occur in the Azores. In northern Europe,

B.media

is found in the Baltic, Karelia (southern part),Ladoga-Ilmen, Dvina-Pechora (western and southernparts), Upper and Middle Dniepr, the Upper Volga,Volga-Kama, Volga-Done (northern part), Ural (cen-tral and southern), Carpathians and the Caucasus(Tsvelev 1984). Dahl (1998) refers

B. media

to a south-ern boreal sub-element, and Preston & Hill (1997)assign it to the European temperate floristic element.

Outside Europe,

B. media

has been recorded fromSyria and Turkey, and from Kashmir, Myanmar, Nepaland Tibet. The species is also recorded from SouthAfrica, and from Australia and New Zealand (Vergl.Chor.) as an alien. In North America, the species isintroduced and occurs in Connecticut, Massachusetts,Michigan and Vermont in the United States and in BritishColumbia and Ontario in Canada (Hitchcock 1971).

Briza media

is found to 65

°

N in Europe (Sweden), to

c

. 30

°

N in Asia and to

c

. 50

°

N in North America.

*Abbreviated references are used for standard works, see

Journal of Ecology

(1975),

63

, 335–344. Nomenclature ofvascular plants follows

Flora Europaea.

JEC_684.fm Page 737 Saturday, July 27, 2002 11:23 AM

738

J. M. Dixon

© 2002 British Ecological Society,

Journal of Ecology

,

90

, 737–752

In England,

B. media

has an altitudinal range fromsea-level to 640 m (Cumbria), from sea-level to 515 m inWales (Tal-y-Fan), from sea-level to 655 m in Scotland(Atholl) and from sea-level to 427 m in Ireland (Wick-low) (Alt. Range Br. Pl.). It is found to 1870 m in theAlps (Pfl. Exk.), to 3000 m in the Caucasus, to 1000 min the Carpathians, to 1450 m in the Pyrenees, to 3500m in Nepal and to 4500 m in the north-west Himalayas.

II. Habitat

(

)

Briza media

is exposed to annual precipitation ofaround 1700 mm on the Isle of Mull and to conditionswith less than 1 mm precipitation during July andAugust in southern Spain, where average monthlymaximum temperatures are around 43

°

C (Meteoro-logical Office 1972). It experiences temperatures as lowas

−

35

°

C in January in Estonia; however, the effects ofthese low temperatures are moderated by an insulatingblanket of up to 20 cm of snow, which normally persistsfrom November to the beginning of April (Lippmaa1931).

No evidence in Britain of wind or insolation damagehas been noted, and the species is found on steep dryslopes in the Jura Alps subject to strong insolation, andto Föhn-swept slopes in Germany (Braun-Blanquet1939).

Briza media

is found both on flat ground and onslopes up to about 60

°

, but is most common on slopesbetween 20 and 40

°

(Grime

et al

. 1988). The speciesshows no aspect preference in the British Isles nor inwestern and central Europe.

(

)

Briza media

is a component of semi-natural calcareouspastures, scree slopes, quarry spoil and road verges,and has been recorded from old meadows and enclosedpastures (Grime

et al

. 1988). It is widespread on brownearths, shallow free-draining rendzinas and greyrendzinas overlying chalk and limestone in England,but is less frequent on these in Wales and northernScotland. Grubb

et al

. (1969) recorded

B. media

fromtall chalk heath at Lullington Heath, Sussex, andIvimey-Cook & Proctor (1966) recorded it from lime-stone heath in the Burren, Co. Clare. The species hasalso been recorded from wet heathy roadsides and from

Fig. 1 The distribution of Briza media in the British Islea. (�) Pre-1950; (�) 1950 onwards. Each dot represents at least one record ina 10-km square of the National Grid. Mapped by Henry Arnold, Biological Records Centre, Centre for Ecology and Hydrology,using Alan Morton’s DMAP programme, mainly from records made by members of the Botanical Society of the British Isles.


739

Briza media

L.


Journal of Ecology

,

90

, 737–752

water meadows on rich soils (Edees 1972), from lime-stone swamps (Horwood & Noel 1933), grazed fenflushes (Sinker

et al

. 1985) and from calcareous mires(Grime

et al

. 1988). It is also recorded from calcareouspeats and from clays with impeded drainage (Sinker

et al

. 1985), from Keuper marls and Carboniferousshales (Newton 1971), from Coal Measures (Graham1988), from Liassic clays and marls, from Bunter sand-stone, from incipient podsols (Balme 1953), from neu-tral to acidic grassland and heaths (Grose 1957) andfrom the very acid sands of the Weald, with pH < 4.0(C. Stace, personal communication). It is recordedfrom volcanic rocks and stabilized sand dunes in Wales(Benoit & Richards 1961), from coastal sands in York-shire (Crackles 1990), and from dry dune pasture atBraunton Burrows, north Devon (Willis

et al

. 1959).

Briza media

occurs on brown forest soils, on high basestatus humic gleys, peaty gleys and flushed peat in Scot-land (Gauld & Robertson 1985) and also from raw soilson sandy river shingle (Birse 1980).

Briza media

is recorded as occurring in soils ofbetween pH 4.0 and 8.0 but most frequently in soils ofaround pH 7.0 (Ecol. Atl.).

Soil analyses (methods according to Chem. Anal.)for 15 British sites supporting

B. media

gave a range ofexchangeable calcium and magnesium, extracted withM ammonium acetate (pH 9.0), from 1200 to7500 mg kg

−

1

and from 30 to 500 mg kg

−

1

, respectively,while potassium ranged from 30 to 540 mg kg

−

1

. Phos-phate phosphorus, extracted with 0.5

sodium bicar-bonate (pH 8.5), ranged from 5 to 39 mg kg

−

1

and totalnitrogen from 0.1 to 1.9%.

In Continental Europe, in addition to soils overlyingcalcareous rocks,

B. media

occurs on calcareousmoraines (Sterner 1922), on dry shell deposits (Willems1982), on slate (Andersson 1970) in southern Sweden,on porphyr and gypsum (Meusel 1940), on dry acidsoils (Ellenberg 1988) in Germany, and from biotiteand granite gneiss in Switzerland (Marschall 1947).

While

B. media

may be considered as most typicallya plant of fairly dry, well-drained calcareous soils, it hasa very wide edaphic tolerance, growing successfully indistinctly acidic soils, wet and poorly drained sites andon soils of many different textures.

III. Communities

Briza media

is predominantly a species of calcareousgrasslands and occurs with a high constancy in the fol-lowing communities defined by the National Vegeta-tion Classification (Rodwell 1991, 1992).

CG1

Festuca ovina–Carlina vulgaris

grassland isfound on freely (often excessively) draining rendzinasoils with a high base status, on steep and rocky, butstable, slopes on hard limestones, usually with a south-erly to westerly aspect and so with a tendency to sum-mer droughting. Often heavily grazed by sheep andrabbits, this community is confined to Devonian Lime-stone in Devon and to Carboniferous Limestone in

Wales and the Mendips.

Briza media

has an overallconstancy of III in CG1 but attains a constancy of IV inthe subcommunities of

Helianthemum canum

and

Trinia glauca

and a constancy of V in the

Koeleria mac-rantha

subcommunity. Constant species, as defined bythe NVC, for CG1 and the following communities aregiven in Table 1.

CG2

Festuca ovina–Avenula pratensis

grassland con-sists of a rich mixture of grasses and dicotyledons in aclosed sward and is traditionally grazed by sheep andrabbits. It occurs most frequently in relatively dry andwarm, lowland climates on free-draining calcareoussoils derived from calcareous bedrock, often prone tosummer droughting.

Briza media

has a constancy of IVin this community.

CG3

Bromus erectus

grassland achieves maximumextent on lightly grazed or ungrazed grasslands overChalk in the south-eastern areas of Britain, and overthe Oolite of the Cotswolds and Northhamptonshire.

Briza media

has an overall constancy of III in this com-munity, but a constancy of IV in the subcommunities of

Centaurea nigra

and

Knautia arvensis–Bellis perennis

.CG4

Brachypodium pinnatum

grassland is alsomainly associated with lightly or ungrazed calcareousswards in south-eastern Britain, but is more generallyfound on the cooler and damper areas of the Chalk andOolite than is the

Bromus erectus

grassland, which ismore continental in character.

Briza media

has an over-all constancy of III in this community.

CG5

Bromus erectus–Brachypodium pinnatum

grass-land occurs where

B. pinnatum

is favoured by amel-ioration of extreme Continental conditions, but not sogreatly as to exclude

Bromus erectus

. The community ismost characteristic on the calcareous, base-rich soils ofthe Oolite on the north-western fringe of lowland lime-stones of the Cotswolds and Northhamptonshire/Lincolnshire scarps.

Briza media

has an overall constancyof IV and of V in the

Hieracium

spp. subcommunity.CG6

Avenula pubescens

grasslands are found on avariety of gently sloping lowland limestones, mainly inthe south of England. The soils are deep and moist,though mostly free-draining alluvial rendzinas, or cal-careous brown earths, and in some cases more meso-phytic soils occur on flat limestones. This community islightly grazed by cattle; on sloping limestones it isgrazed by rabbits.

Briza media

has an overall constancyof only II in this community, but achieves a cons-tancy of III in the

Dactylis glomerata–Briza media

subcommunity.CG8

Sesleria albicans–Scabiosa columbaria

grass-land is found only on free-draining calcareous, steepslopes of Magnesian Limestone in Durham, prin-cipally on rendzinas rich in calcium and magnesiumcarbonates. The climate is cool and dry, and thecommunity is a plagioclimax vegetation maintained bygrazing of domestic animals and rabbits.

Briza media

has a constancy of IV in CG8.CG9

Sesleria albicans–Galium sterneri

grassland isfound in the northern Pennine submontane or montane


740

J. M. Dixon


Journal of Ecology

,

90

, 737–752

climate, over shallow, freely draining but moist, cal-careous lithomorphic soils on drift-free CarboniferousLimestone exposures. It forms an important part ofupland farm hill-pasture and as such is frequentlygrazed, mainly by sheep. In CG9,

Briza media

reaches anoverall constancy of IV and a constancy of V in the

Carex capillaris–Kobresia simpliciuscula

subcommunity.

Briza media

occurs with a low constancy (I) in thecalcareous grassland community of

Festuca ovina–Hieracium pilosella–Thymus praecox/pulegioides

(CG7)and in the

Festuca ovina–Agrostis capillaris–Thymuspraecox

grassland (CG10).

Briza media

is also a component of the followingmesotrophic grasslands.

MG3

Anthoxanthum odoratum–Geranium sylvaticum

grassland. This is a northern submontane communityalmost entirely restricted to a few valleys in northernEngland where traditional hay-meadow managementoccurs, and comprises a dense community of grassesand herbs.

Briza media

attains an overall frequency ofI but a frequency of III in the

B. media

subcommunity.The constant species for this and the following grass-land community are given in Table 2.

Table 1 Constant species of British calcareous grassland communities (see text) containing Briza media

Species

Calcareous grasslands

CG1 CG2 CG3 CG4 CG5 CG6 CG8 CG9

Avenula pratensis – IV – – – IV IV –Avenula pubescens – – – – – IV – –Brachypodium pinnatum – – – V V – – –Briza media V IV IV III IV III IV IVBromus erectus – – V – V – – –Campanula rotundifolia – – – – – – – IVCarex flacca – V IV IV V – V IVCarlina vulgaris IV – – – – – – –Centaurea nigra – – – – – – IV –Cirsium acaule – – – – IV – – –Ctenidium molluscum – – – – – – – IVDactylis glomerata IV – – – – – – –Festuca ovina V V IV V IV – IV IVFestuca rubra – – – – – V – –Galium sterneri – – – – – – – IVGalium verum – – – – – – IV –Helianthemum nummularium – – – – IV – IV IVHieracium pilosella IV IV – – IV – – –Hypnum cupressiforme – – – IV – – – –Leontodon hispidus – IV – – IV – – –Linum catharticum – IV – – – – V IVLotus corniculatus IV IV IV – IV IV IV –Pimpinella saxifraga – – – – – – IV –Plantago lanceolata IV IV IV – – – IV –Pseudoscleropodium purum – – – – – IV – –Sanguisorba minor V V V – IV – V –Scabiosa columbaria – IV – – – – IV IVSesleria albicans – – – – – – V IVTaraxacum officinale agg. – – – – – IV – –Thymus praecox V IV – IV IV – IV VThymus praecox/pulegioides – – – IV – – – –Viola riviniana – – – – – – – IV

Table 2

Constant species of mesotrophic grassland communities(see text for numbering) containing

Briza media

Species

Mesotrophic grasslands

MG3 MG5

Agrostis capillaris

IV IV

Alchemilla glabra

IV –

Anthoxanthum odoratum

V IV

Centaurea nigra

– IV

Cerastium fontanum

V –

Conopodium majus

V –

Cynosurus cristatus

– V

Dactylis glomerata

IV IV

Festuca rubra

IV V

Geranium sylvaticum

V –Holcus lanatus IV IVLotus corniculatus – VPlantago lanceolata V VPoa trivialis IV –Ranunculus acris V –Rumex acetosa V –Sanguisorba officinalis IV –Trifolium pratense – IVTrifolium repens IV IV


741Briza media L.

© 2002 British Ecological Society, Journal of Ecology, 90, 737–752

MG5 Cynosurus cristatus–Centaurea nigra grass-land occurs throughout the British lowlands. Brizamedia has a constancy of III in the subcommunity ofGalium verum, found mostly over calcareous bedrocks,and a constancy of III in the Danthonia decumbens sub-community, mainly occurring on the upland marginsof northern England and Wales.

The species is also found at a low constancy in themesotrophic grassland communities of Arrhenatherumelatius (MG1), Arrhenatherum elatius–Filipendulaulmaria (MG2), Alopecurus pratensis–Sanguisorbaofficinalis (MG4), Cynosurus cristatus–Caltha palustris(MG8), and Holcus lanatus–Deschampsia cespitosagrassland (MG9), and also in the calcifuge sward ofFestuca ovina–Agrostis capillaris–Galium saxatilegrassland (U4). Briza media is also found as a minorcomponent of the Salix repens–Campylium stellatumdune-slack community (SD14).

Briza media is a component of several mire commu-nities; constant species for these are given in Table 3.

M10 Carex dioica–Pinguicula vulgaris mire is typi-cally a soligenous mire kept very wet by base-rich, cal-careous and oligotrophic waters. This is predominantlya community of north-western Britain, where the cool,wet climate influences the structure and floristics of thevegetation. Most stands are grazed by large herbivores

and trampling by these plays a large part in maintain-ing an open community. Briza media has a constancy ofIV in the Briza media–Primula farinosa subcommunityand an overall constancy of II.

M13 Schoenus nigricans–Juncus subnodulosus mire isconfined to peat or mineral soils irrigated by base-rich,highly calcareous and oligotrophic waters. This com-munity is often found below springs and seepage lines,or on flushed margins of valley mires, and is restrictedto the warmer southern parts of Britain. Some standshave been affected by mowing, burning and peat-dig-ging; grazing sometimes affects the floristics and struc-ture of the vegetation. Briza media has a constancy of Vin the Briza media–Pinguicula vulgaris subcommunityand an overall constancy of II.

M22 Juncus subnodulosus–Cirsium palustre fen-meadow is predominantly a community of moderatelymesotrophic and moist, base-rich peats and mineralsoils found in lowland southern Britain. It occurs eitheraround well-developed flushes, springs and mires ordelineates the influence of more ill-defined areas of sur-face waters. The identity of the community is main-tained by mowing and/or grazing. Briza media has aconstancy of IV in the Briza media–Trifolium spp. sub-community and an overall constancy of II.

M26 Molinia caerulea–Crepis paludosa mire is a verylocal community of moderately base-rich, moist, cal-careous peats and peaty mineral soils in the submon-tane grasslands of the northern Pennines. It can befound either as a stable component around open watersand mires, but also on flushed slopes in soligenous sit-uations, often subject to grazing. Briza media has aconstancy of V in the Festuca rubra subcommunity andan overall constancy of III.

Briza media is also a minor component in theMolinia caerulea–Cirsium dissectum fen-meadow(M24) and the Cratoneuron commutatum–Carex nigraspring community (M38).

Briza media is recorded from Scotland (Birse 1980)from the Polygono–Helictotrichetum pratensis associa-tion which is a woodland replacement community cre-ated by grazing on rendzinas and shallow brown,calcareous soils. The characteristic species are Avenulapratensis, Carex caryophyllea, Helianthemum nummu-larium, Koeleria macrantha, and Polygonum viviparum.Birse (1980) also describes B. media as a minor com-ponent of the Anthyllido–Rhacomitrietum canescentisassociation, a pioneer community of river flood plains.

In Ireland, B. media is recorded from the meso-trophic grassland Cynosurus cristatus–Centaurea nigra(MG5), which is the typical grassland of well-drainedpastures over limestone, usually grazed by cattle.O’Sullivan (1982) records B. media from the Junco–acutiflori–Molinietum association of wet meadows,together with Cynosurus cristatus, Lotus corniculatus,Phleum pratense, Trifolium pratense and Trifoliumrepens.

Briza media is also recorded by Ní Lamhna (1982)from the Festuco–Galietum maritimi sand dune vegetation

Table 3 Constant species of mire and fen-meadowcommunities (see text) containing Briza media

Species

Mire and fen-meadow community

M10 M13 M22 M26

Aneura pinguis IV – – –Bryum pseudotriquetrum IV – – –Calliergon cuspidatum – V V IVCampylium stellatum IV IV – –Carex dioica IV – – –Carex hostiana IV – – –Carex lepidocarpa IV – – –Carex nigra – – – VCarex panicea IV V – VCarex pulicaris IV – – –Cirsium palustre – – IV –Crepis paludosa – – – VCtenidium molluscum IV – – –Drepanocladus revolvens IV – – –Equisetum palustre – – IV IVEriophorum angustifolium IV – – –Filipendula ulmaria – – IV IVHolcus lanatus – – IV –Juncus articulatus IV – – –Juncus subnodulosus – V V –Lotus uliginosus – – IV –Mentha aquatica – – IV –Molinia caerulea – V – VPinguicula vulgaris V – – –Potentilla erecta – IV – IVRanunculus acris – – – IVSchoenus nigricans – V – –Succisa pratensis – IV – IVValeriana dioica – – – V


742J. M. Dixon


of Malahide Island, north of Dublin, which is foundon middle dunes of grass-dominated, ungrazed orvery lightly grazed, vegetation. Differential speciesare Anthoxanthum odoratum, Briza media, Dicranumscoparium, Euphrasia occidentalis, Koeleria macrantha,Potentilla sterilis, Pteridium aquilinum, Rosa pimpinel-lifolia, Thymus praecox and Trifolium repens.

Ivimey-Cook & Proctor (1966) recorded B. mediafrom the Galium verum–Asperula cynanchica nodum, acalcareous dune community of the Burren, Co. Clare,together with Agrostis stolonifera, Asperula cynan-chica, Carex flacca, Ctenidium molluscum, Euphrasiasalisburgensis, Festuca ovina, F. rubra, Galium verum,Lotus corniculatus, Plantago lanceolata, Prunella vul-garis, Thymus praecox and Viola riviniana, and alsofrom the Hyperico–Dryadetum association. This is ashrub-dominated community found on leachedorganic soil over bare limestone. Characteristic speciesare Calluna vulgaris, Danthonia decumbens, Dryasoctopetala, Empetrum nigrum, Hylocomium splendens,Hypericum pulchrum, Hypnum cupressiforme var. eric-etorum, Neckera crispa, Polygala vulgaris and Rosapimpinellifolia. Ivimey-Cook & Proctor (1966) alsorecorded B. media from a Burren calcareous springcommunity, together with Anagallis tenella, Cardaminepratensis, Carex lepidocarpa, C. panicea, Juncus artic-ulatus, Molinia caerulea, Pinguicula vulgaris and Suc-cisa pratensis.

Briza media has been observed by the author in alightly shaded railway cutting, and on roadsides in the

shade of pines in Sutherland. It has been recorded froma stream-side in a pine plantation in Spain, in oakwoods in the Pindos Mountains of Greece, in sparseoak-wood in southern Sweden, in forest-steppe in cen-tral Europe, in Juniper drifts in Estonia and in a decid-uous coniferous forest in Nepal.

In continental Europe, B. media occurs in a numberof associations of the Brometalia erecti throughoutwestern Europe; these occur on dry steep slopesthroughout the Alpine range, in dry rocky places inFrance and Belgium, the deeper moister soils of theDanube and Rhine valleys and also on more humidslopes of the Alps. Briza media also occurs in someassociations of the class Arrhenatheretalia. A range ofcommunities containing B. media, with a frequency ofIII and above, is given in Tables 4 and 5 to illustrate itsgeographical and ecological range. The latter is, like theedaphic range, very wide, embracing dry and damphabitats, including lowland, montane and alpine sites,so involving a high number of vascular plant speciesassociated with B. media.

IV. Response to biotic factors

It is reported that B. media is a poor competitor whichfails to persist in derelict grassland (Sikula 1978; Grimeet al. 1988), while Watt (1974) described it as showing areduced frequency in ungrazed chalk grasslandenclosed for 34 years. That B. media is not a good com-petitor is supported by the work of McLellan et al.

Table 4 A selection of the communities in which Briza media occurs in Continental Europe

Habitat and community Region Reference

Group 1. Moderately dry to damp pastures and river valleysCarex flacca community Sweden Andersson (1970)Cirsium oleraceum–Polygonum bistorta Germany Hundt (1958)Origano–Brachypodietum agrimonietosum Poland Kota¢ska (1970)Molinietum medioeuropaeum Germany Ellenberg (1988)Sesleria–Filipendula hexapetala Estonia Lippmaa (1931)

Group 2. Montane, subalpine and alpineAndropogonetum grylli insubricum Switzerland & Italy Braun-Blanquet (1939)Antherico–Brometum Switzerland Willems (1982)Carex humilis–Trinia glauca Italy Braun-Blanquet (1939)Centaurea nigrae–Arrhenatheretum Germany Oberdorfer (1978)Mesobrometum collinum France Willems (1973)Trisetum flavescentis Austria Knapp & Knapp (1953)

Group 3. North-facing slopes over gypsumParnassio–Seslerietum variae Germany Schubert (1963)

Group 4. Dry shelly and glacial deposits, rock outcropsHelicto–Caricetum Sweden Willems (1982)Koelerio–Festucetum Poland Korna£ (1949)Solidagini–Helictotrichetum Denmark Willems et al. (1981)

Group 5. Chalk slopesMesobrometum Germany Braun-Blanquet (1939)Seslerio–Polygaletosum France Stott (1971)Phleetum phleoidis–Sedetosum montani France Braun-Blanquet (1939)

Group 6. Forest-steppeSeslerietum rigidae Germany Meusel (1940)


743Briza media L.


Table 5 Species associated with the groups given in Table 4

Species

Group

1 2 3 4 5 6

Abies alba − − − − − +Achillea millefolium + − − − − −Achillea ptarmica + − − − − −Agrimonia eupatoria + − − + − −Agrostis capillaris − + − − − −Agrostis gigantea + − − − − −Agrostis stolonifera + − − − − −Alchemilla vulgaris agg. + + − − − −Alopecurus pratensis + − − − − −Anemone nemorosa + − − − − −Angelica sylvestris + − − − − −Antennaria dioica + − − − − −Anthericum ramosum − + − − − −Anthoxanthum odoratum + + − − + −Anthriscus sylvestris − + − − − −Anthyllis vulneraria + − − + − +Arabis hirsuta − − − + − −Armeria maritima − − − + − −Arrhenatherum elatius − + − − − −Asperula cynanchica − + − − + −Aster linosyris − + − − − −Avenula pratensis + + − + − −Avenula pubescens − + − − − −Bellis perennis + + − − − −Brachypodium pinnatum + + − + + +Bromus erectus − + − − + −Calamagrostis arundinacea − − − − − +Calluna vulgaris − − − − + −Caltha palustris + − − − − −Campanula persicifolia − + − − − −Campanula rotundifolia − − + − + −Campanula scheuchzeri − + − − − −Cardamine pratensis + − − − − −Carex caryophyllea − + − + − −Carex diversicolor + − − − − −Carex flacca + − − − + −Carex hartmanii + − − − − −Carex humilis − + − − + −Carex panicea + + − − − −Carlina acaulis − − − − + −Centaurea jacea + + − + − −Centaurea nigra − + − − − −Centaurea scabiosa + + − + − −Cerastium fontanum ssp. scandicum + + − − − −Chrysopogon gryllus − + − − − −Cirsium acaule − + + − − −Cirsium helenioides + − − − − −Cirsium palustre + − − − − −Cirsium tuberosum + − − − − −Coeloglossum viride − − − − + −Coronilla varia + + − + − −Crepis biennis − + − − − −Crepis paludosa + − − − − −Crocus vernus ssp. albiflorus − + − − − −Cynosurus cristatus − + − − − −Cytisus supinus − − − + − −Dactylis glomerata − + − + − −Danthonia decumbens + − − − − −Daucus carota − − − + − −Deschampsia cespitosa + − − − − −Equisetum arvense + − − − − −Eriophorum angustifolium + − − − − −Euphorbia cyparissias − + + + − −Fagus sylvatica − − − − − +

Table 5 continued

Species

Group

1 2 3 4 5 6

Festuca ovina + − − − − −Festuca pratensis − + − + − −Festuca rubra + + − + + −Festuca rupicola − + − − − −Filipendula ulmaria + − − − − −Filipendula vulgaris + − − − − −Fragaria vesca + − − − − −Fragaria viridis + − − − − −Fraxinus excelsior − − − − − +Galium boreale + − − − − −Galium mollugo − + − − + −Galium uliginosum + − − − − −Galium verum + − − + − −Genista tinctoria − − − + − −Geranium sanguineum − + − + − −Globularia vulgaris − + − − − −Gymnadenia conopsea − + − − − −Helianthemum nummularium − + − + − +Helianthemum ovatum + − − − − −Hieracium pilosella + + + − − −Hieracium vulgatum group − − − − + −Hippocrepis comosa − + − − − −Holcus lanatus + + − − − −Hypericum perforatum + − − + − −Inula hirta − − − + − −Juncus articulatus + − − − − −Juncus conglomeratus + − − − − −Knautia arvensis − + − + − −Koeleria macrantha − − − − + −Koeleria pyramidata − − + − − −Lathyrus pratensis + + − − − −Leontodon hispidus + + − − − −Leucanthemum vulgare + + − − − −Linum catharticum − − + − − −Linum tenuifolium − + − − − −Listera ovata − + − − − −Lotus corniculatus − − − + − −Luzula campestris + − − − − −Luzula multiflora + − − − − −Lychnis flos−cuculi + + − − − −Medicago lupulina − − − + − −Mentha arvensis + − − − − −Molinia caerulea + − − − − −Myosotis scorpioides + − − − − −Nardus stricta + − − − − −Onobrychis arenaria − + − − − −Ophrys apiflora − + − − − −Ophrys insectifera − + − − − −Ophrys sphegodes − + − − − −Origanum vulgare − − − + − −Parnassia palustris − − + − − −Peucedanum cervaria − − − + − −Peucedanum oreoselinum − + − − − −Phleum phleoides − − − + + −Pimpinella major − + − − − −Pimpinella saxifraga + + + + − −Pinus nigra − − − − − +Plantago lanceolata + + − + + −Plantago media − + − − − −Platanthera chlorantha − + − − − −Poa pratensis + + − − − −Polygala amarella − − + − + −Polygala comosa − + − − − −Potentilla erecta + + − − − −


744J. M. Dixon


(1997), who noted in a removal experiment that B.media was more productive with increasing gap sizebetween plants. They concluded that the speciesappears to be negatively affected by a high density ofneighbours and that it is suppressed by diffuse compe-tition at normally observed densities.

Sinker et al. (1985) reported that B. media persistedin grassland mown annually, and Baker (1937) observedit was present in hay meadows which were grazed duringthe period of autumn to early spring and then mown in

mid-July However, Mitchley & Willems (1995) notedthat in Dutch grasslands, subjected to an autumn mowingregime, this was insufficient to prevent taller grasses,such as Brachypodium pinnatum, from suppressing mostother growth, including that of B. media.

Briza media appears able to withstand a reasonablyheavy grazing regime: it is a component of high con-stancy in for example the calcareous grassland commu-nities of Festuca ovina–Carlina vulgaris (CG1) andFestuca ovina–Avenula pratensis (CG2) which arereported as being often heavily grazed by sheep andrabbits, and B. media is also described from a woodlandplagioclimax community in Central Perthshire, Scot-land, which is maintained principally by the grazing ofcattle, red deer, rabbits and hares (Gauld & Robertson1985). Sikula (1978) noted that the species is readilygrazed by cattle and Sinker et al. (1985) reported that itis tolerant of heavy grazing; it is also recorded as fre-quent on sites heavily grazed by rabbits in Hertford-shire (Dony 1967). However, although the speciesmight be tolerant of heavy grazing, a simulated grazingexperiment by the author, with clipping at three heightregimes every two weeks for 10 weeks, resulted in thegreatest production of material in the unclipped con-trol plants.

Sinker et al. (1985) reported that B. media is very tol-erant of trampling. Plants on the edges of paths pro-duce more horizontal rosette-type growth, but noinflorescences have been observed by the author onthese prostrate, trampled plants.

Lloyd (1968) noted that fire significantly stimulatedthe production of inflorescences in B. media in thesummer following a spring burn, but by the followingyear no significant stimulus to flower productionremained.

V. Response to environment

( )

Briza media is usually found as scattered plants inungrazed grassland, with a few groups of tillers joinedby short rhizomes. In grazed grassland and on screes itgrows as small tussocks. Briza media never produceslarge tussocks; even after 2 years in cultivation theaverage tussock diameter was only about 12 cm.

( )

Table 6 illustrates that Briza media is more productivein damp to wet habitats in comparison to dry ones, withlonger leaves, culms and panicles. Leaf width, however,is not significantly different. The number of spikelets isalso significantly greater in damp, ungrazed grasslandcompared with dry, ungrazed grassland. Althoughreported as absent from woodland (Grime et al. 1988),the species has been found in lightly shaded sites by theauthor, where it has flowered and set seed. Leaf andculm measurements and spikelet number in a shaded

Table 5 continued

Species

Group

1 2 3 4 5 6

Potentilla reptans + − − + − −Potentilla tabernaemontani − + − − − −Primula auricula − − − − − +Primula veris − + − − − −Primula vulgaris + − − − − −Prunella grandiflora − + − − − −Pulsatilla vulgaris − + − − − −Ranunculus acris + + − − − −Ranunculus bulbosus − + − − − −Ranunculus repens + − − − − −Rhinanthus minor + − − − − −Rumex acetosa + + − − − −Rumex arifolius − + − − − −Salvia pratensis − + − − − −Sanguisorba minor − + − − − −Sanguisorba officinalis + − − − − −Saxifraga aizoides − − − − − +Scabiosa columbaria − + + − + +Scabiosa ochroleuca + − − + − −Sedum ochroleucum ssp. montanum − − − − + −Serratula tinctoria + − − − − −Sesleria albicans − − + − + −Sesleria caerulea + − − − − −Sesleria rigida − − − − − +Silaum silaus + − − − − −Silene nutans − + − − − −Silene vulgaris − + − − − −Solidago virgaurea − − − + − −Sorbus aria − − − − − +Stachys officinalis + + − − − −Stachys recta − + − − − −Succisa pratensis + − − − − −Syringa sp. − − − − − +Taraxacum officinale agg. + − − − − −Tetragonolobus maritimus − + − − − −Thalictrum minus − + − − − −Thymus serpyllum − + + + + −Tragopogon pratensis ssp. orientalis − + − − − −Trifolium alpestre − − − + − −Trifolium dubium − + − − − −Trifolium montanum + + − − + −Trifolium pratense − + − − − −Trifolium repens + + − − − −Trifolium rubens − − − + − −Trinia glauca − + − − − −Trisetum flavescens − + − − − −Trollius europaeus − + − − − −Valeriana dioica + − − − − −Veronica spicata − − − − + −Vincetoxicum hirundinaria − + − + − −


745Briza media L.


railway cutting were not significantly different fromthose of ungrazed grassland plants (Table 6). However,B. media does not flower where the irradiance is lessthan c. 50% of full sun (see VI (E)).

The species sets seed throughout its range.

( ) ,

As B. media grows almost as far north as the Arctic Cir-cle and to 4550 m in the Himalayan Range, it is pre-sumably frost tolerant, and no evidence of frostdamage has been observed in Britain. Davison (1964),carrying out field experiments, noted that seedlings ofB. media suffered no mortality during the winter, andtolerated snow cover from December to March.

When B. media is subjected to water deficits the innerleaves of a tiller become inrolled and the outer leavesquickly dry and become ‘ridged’ in appearance anddroop. Many of the leaves also become twisted giving aspiralling effect. As the tips of the leaves necrose theyoften develop a purplish coloration before becomingstraw-coloured and dying.

The species appears to be principally a drought avoi-der, as most of its leaves are produced by the end ofApril before the onset of periods of drought. Brizamedia does not seem to develop any rooting strategiesto combat drought as seen for example in Koeleria mac-rantha (Dixon 2000). Reader et al. (1992) observed thatthe rooting depth of B. media in unwatered soil was nodifferent from that in watered soil, and they concludedthat its roots are unable to ‘seek out’ water in unwa-tered soil.

As Briza media occurs in damp to wet meadows andis a component of calcareous mire communities(Wheeler 1980), it appears moderately tolerant ofwaterlogging. In a pot experiment in which plants weresubjected to normal watering, one-third, two-thirdsand total waterlogging conditions for 1 year, the one-third waterlogged plants had the longest leaves and thegreatest shoot and root dry weights: there was no signific-ant difference in shoot weight between those waterednormally and those subjected to two-thirds and totalwaterlogging. Leaf lengths for the normally wateredand the two-thirds waterlogged plants were not signific-

antly different, and that for the totally waterloggedplants was only just significantly less than for the one-third waterlogged. However, plants with two-thirds andtotal waterlogging had significantly lower root dryweights than those of the normally watered plants.

VI. Structure and physiology

( )

Briza media has a dense fibrous rootstock with shortthick rhizomes which terminate in leafy shoots. Itappears to have little plasticity in its rooting depth andReader et al. (1992) observed that species which regen-erate both from seed and vegetatively, as does B. media,show less plasticity in seedling rooting depth than dospecies which regenerate from seed only. Mean rootingdepth of B. media in well-watered loam in West York-shire was c. 40 cm, while Kota¢ska (1970) reported amean rooting depth of 30 cm in a xerothermic grass-land on a shallow brown rendzina.

The leaf sheaths of B. media are brown, fibrous andmoderately persistent, as are the leaves, decomposingslowly, and so adding to the litter layer.

Solitary growth in Briza media results in small tus-socks, which increase mainly by the production ofshort leafy tillers produced at the tips of the short rhi-zomes. In longer vegetation B. media grows as stragglygroups of just a few tillers.

Briza media invests heavily in roots, rather less ininflorescences and much less so in leaves. Twenty youngplants (each of 3 tillers) cultivated in good loam in WestYorkshire for a year gave a mean dry weight (± SE) perplant of 12.7 (± 1.4) g inflorescences (culms and pani-cles), 28.0 (± 3.2) g roots and 8.3 (± 1.3) g shoots (livingand dead). Thus the culms comprised 26%, the roots57% and the tillers 17% of the total dry weight. This isthe same pattern as that shown by Avenula pubescens,which invested 57% in roots, 30% in inflorescences and12% in tillers (Dixon 1991).

At the time of harvesting (mid July) the livingshoots provided about three-quarters of the total shootmaterial.

Stomatal counts from plants in grazed limestonegrassland in North Yorkshire gave a mean of 61.4

Table 6 Mean (± SE) morphological measurements for Briza media from different habitats

Variable

Habitat*

Dry ungrazed grassland

Lightly grazed grassland

Shaded railway cutting

Damp ungrazed grassland

Calcareous mire

Leaf length (cm) 14.4 (1.0) 6.3 (0.5) 15.2 (1.4) 18.1 (1.1) 19.6 (0.6)Leaf width (mm) 4.2 (0.3) 2.5 (0.1) 3.5 (0.2) 3.2 (0.2) 5.3 (0.3)Culm length (cm) 35.9 (0.9) 30.9 (2.3) 38.7 (1.9) 46.1 (2.0) 40.0 (2.2)Panicle length (cm) 7.9 (0.3) 6.3 (0.3) 7.6 (0.5) 10.1 (0.5) 10.0 (0.3)No. of spikelets 26.1 (1.7) 19.6 (1.8) 25.5 (3.2) 30.7 (2.4) N/A

*Dry ungrazed grassland: Skirethorn; Lightly grazed grassland: Littondale; Shaded railway cutting: Halton Gill; Damp ungrazed grassland, Wharfedale; Calcareous mire: Ribblesdale. All in North Yorkshire.


746J. M. Dixon


(± 4.4) mm−2 for the adaxial leaf surface and 46.5(± 3.2) mm−2 for the abaxial surface: the counts weremade at three positions along the length of 20 leaves.The stomata occur in rows between the veins, withrather more stomata around the middle of the leaf andfewer towards the tip.

( )

Briza media is listed as being vesicular-arbuscularmycorrhizal by Harley & Harley (1987) and theyreported a high colonization rate from July to Septem-ber. Read & Haselwandter (1981) noted that B. mediafrom the northern calcareous Alps had a typically60% colonization (Glomus sp.), while Mejstrik (1972),describing a Molinietum caeruleae association fromBohemia, also reported that B. media was stronglycolonized.

Grime et al. (1987) observed that B. media producedits highest yield when ungrazed and with mycorrhizalinfection, and its lowest yield also when ungrazed butwith no mycorrhizal infection, compared with grazed,with and without mycorrhizal infection. They noted,however, that the effects of grazing were not significant;that is the effect of grazing was to nullify the influenceof the mycorrhiza.

( ) :

Briza media is a hemicryptophyte. Its leaves die backgradually once flowering has commenced, but plantsretain a number of green leaves throughout winteruntil early spring when new growth starts. Vegetativegrowth is slow and the species never produces largetussocks, but a clone can extend beyond the extent of theoriginal tussock by rhizome growth of at least 6 cmyear−1. It flowers in the first summer after germinationand can produce a moderate number of inflorescences;in cultivation in a good loam these ranged from 7 to 70(mean 29.4 ± 4.4) after one year’s growth.

McLellan et al. (1997) reported that B. media largelyrecruits vegetatively and they comment that this is ageneral strategy where pre- and post-dispersal seed pre-dation is high and the low soil fertility leads to anopportunistic flowering. Briza media failed to flowerduring the course of their experiment, which coveredthe flowering period, further demonstrating the lowfrequency of flowering in nutrient-poor habitats. Itproduces a transient seed bank during the summer,when the caryopses are shed; these germinate nearlysynchronously in the autumn. There is a completeabsence of germinable seeds during spring and earlysummer (Thompson & Grime 1979).

( )

The basic number is seven. Diploids with 2n = 14 arerecorded from Britain (Fl. Br. Isl.), from Portugal(Férnandes & Queiros 1969), from the Canary Isles

(Bramwell et al. 1971) and from Italy (Tornadore et al.1974). Tetraploids with 2n = 28 have been recordedfrom Poland (Frey et al. 1977) and from Bulgaria(Ko∞uharov et al. 1974). Accessory chromosomes arefound in B. media (Bosemark 1957). Nuclear DNA (2Cvalue) = 16.9 pg nucleus−1 (Grime et al. 1988).

( )

Seedling relative growth rate is given by Grime et al.(1988) as 1.0–1.4 week−1.

Ellenberg (1988) described B. media as light-loving,and not found where the relative light flux is less than40%, and although observed by the author in lightlyshaded places, it has not been recorded from wood-lands. Briza media can tolerate quite deep shading in anon-competitive situation, but cannot flower and setseed. Plants grown under neutral artificial shading withreduction in light flux of 43, 33 and 26% producedmuch longer leaves (means of 46.4 ± 2.6, 48.1 ± 2.4 and36.3 ± 3.8 cm, respectively, compared with a meanunshaded leaf length of 18.3 ± 0.9 cm). Leaf width nar-rowed progressively with decrease in light flux from6.6 ± 0.3 mm for unshaded plants to 6.4 ± 0.3, 4.9 ± 0.1and 3.9 ± 0.2 mm, respectively. The same pattern ofelongated, narrow leaves is also shown by the tussockgrasses Deschampsia cespitosa (Davy 1980), Sesleriaalbicans (Dixon 1982) and Avenula pratensis (Dixon1991). However, the non-tussock producing grassesAvenula pubescens and Trisetum flavescens, while pro-ducing longer leaves, do not differ significantly in leafwidth from plants from unshaded habitats (Dixon1991, 1995).

Both tiller and root dry weights declined signifi-cantly with increase in shading: unshaded plants gave amean total tiller weight of 6.5 ± 0.4 g and the shadedplants 4.0 ± 0.6, 2.8 ± 0.3 and 1.8 ± 0.3 g, while meanroot dry weights for the unshaded plants was 7.8 ± 1.2g and for the shaded plants 3.2 ± 0.5, 1.0 ± 0.3 and0.6 ± 0.1 g, respectively. The SLA increased from 2.1 inunshaded plants to 2.4, 2.7 and 3.4 for the percentagelight flux reductions stated above. Briza media did notflower under any of the shading regimes.

When compared with Koeleria macrantha, a speciesalso generally found in well-lit places, under the sameshading regime, B. media showed a much lower produc-tion of both shoots and roots (Dixon 2000).

Although B. media is listed as having a wide ampli-tude in relation to soil moisture (Ellenberg 1988) it doesnot appear to be very drought resistant. Milnes et al.(1998) compared the response of B. media and Koeleriamacrantha to drought and noted that, while both spe-cies showed a similar sensitivity to drought with respectto soil drying and water content, B. media died after20 days of drought while K. macrantha responded withrenewed growth to re-watering at that point.

However, a similar experiment by the author with B.media found that after 28 days of droughting, in plantsre-watered and then harvested 7 days later, 6% of the


747Briza media L.


total shoot material was still living and none of theplants had died completely. In an experiment with avariable watering regime, in which plants were grown inJohn Innes compost with a 14-h day and 18 °C day and14 °C night temperatures, and were watered for 2, 4, 6,8, and 10 days out of every 14 days, two-thirds of theplants subjected to the most severe regime (2 dayswatering) had died by the time the experiment was ter-minated after 10 weeks. No plants died in any of theother regimes, but the 4-day regime had between 40%and 80% dead shoot material at the end. Total shootand root dry weights, however, declined significantlywith increasing severity of water stress.

Two hours after excision, detached leaves of B. mediagrown under ‘dry’ conditions (watered very sparinglytwice a week) exhibited a water deficit of only 35% ofthat shown by excised leaves of plants which had beenwatered freely and kept in a humid environment.

The results of these experiments suggest that, whileB. media cannot withstand severe droughts, it neverthe-less shows adaptability to some degree of droughting.

Calcium, nitrogen and phosphorus requirements wereinvestigated in sand-culture experiments in a growthcabinet with a light flux density of 1500 µmol m−2 s−1

over a 14-h day at 22 °C and a night temperature of18 °C. Calcium was supplied from 5 to 200 mg L−1 asCa(NO3)2 with NaNO3 added to maintain a constantlevel of nitrogen (see Bradshaw et al. 1958). Briza mediaresponded with increased yield to the increasing levelsof calcium, although the yields of both shoots androots were not significantly different between 50 and200 mg L−1. This is in contrast to calcicolous speciessuch as Avenula pratensis and A. pubescens (Dixon 1991),Trisetum flavescens (Dixon 1995) and Koeleria macrantha(Dixon 2000) (which showed significant increases inyields with 200 mg L−1) reflecting perhaps its distribu-tion on neutral to acidic soils as well as calcareous soils,and a reduced ability to exploit high levels of calcium.

With nitrogen levels of 3, 9, 27, 81 and 243 mg L−1,supplied as Ca(NO3)2 and NaNO3 for the highest level(see Bradshaw et al. 1964), an optimum yield wasobtained at 81 mg L−1, which was significantly differentfrom those of the other treatments: this pattern reflectsthose of Avenula pratensis, A. pubescens and Koeleriamacrantha (Dixon 1991, 2000). Root growth in B.media was affected more detrimentally than shootgrowth at the highest concentration of 243 mg L−1.Briza media is considered to be a species more commonon nitrogen-poor soils than nitrogen-rich soils and itmight be thought that such species would show adap-tations for efficiency in utilization of nitrogen. How-ever, van der Werf et al. (1993) compared B. media,characteristic of nitrogen-poor soils, with Dactylisglomerata, characteristic of nitrogen-rich soils, at arange of nitrogen availabilities. They found that with alow nitrogen supply there was no difference in eitherthe rate of photosynthesis or the photosynthetic nitro-gen use efficiency, but with a high nitrogen supply theefficiency with respect to leaf nitrogen was significantly

higher for D. glomerata than for B. media. The authorssuggested that efficiency in utilization of availablenitrogen is no more a characteristic of non-nutrientdemanding species, such as B. media, than for nutrient-demanding species, such as D. glomerata.

The response of B. media to phosphorus, supplied asNaH2PO4 at 4, 8, 16 and 32 mg L−1 gave the highestyield at the lowest level of 4 mg L−1. There was a ( just)significant decrease at 8 and a very big decrease at 16and 32 mg L−1, these last two concentrations not givingsignificant differences from one another. This responseis different from those of Avenula pratensis and A.pubescens (Dixon 1991) and of K. macrantha (Dixon2000), which all showed optimum yields at 8 mg L−1.

Willems (1980) and Ryser et al. (1997) found that B.media was completely suppressed (by competition pre-sumably) in grasslands where nutrient additions ofnitrogen or phosphorus, or a combination of the two,were added to chalk grassland. However, Grime &Curtis (1976) found that adding phosphate fertilizer toweeded limestone grassland plots, containing seedlingsof four species including B. media, produced a signifi-cant increase in the yield of B. media after growth for5 weeks, and Jeffrey & Pigott (1973) also found thatadding phosphate fertilizer to sugar limestone grass-land in Teesdale led to a positive response by B. media,with a 5-fold increase in cover. The findings of Grime &Curtis and of Jeffrey & Pigott may seem a little surpris-ing when the low requirement in sand culture for4 mg L−1 is considered. However, phosphorus is usuallylimiting in limestone grasslands and the sugar lime-stone in Teesdale was reported by Jeffrey & Pigott asbeing severely deficient (added phosphate is alsolikely to be partly immobilized at high pH in limestonesites as hydroxyapatites). Sesleria albicans did notrespond markedly either to these phosphate additions(Jeffrey & Pigott 1973) and in sand culture this specieshad a very low optimum requirement of 2 mg L−1

(Dixon 1982).Ryser et al. (1997) examined phosphorus allocation

in three grassland species (Brachypodium pinnatum,Dactylis glomerata and B. media). They observed thatphosphorus was allocated to roots and shoots differ-ently depending on how much was added, and thatwith decreasing phosphorus supply the concentrationof the element in the roots of B. media decreased lessthan in the leaves. Tissue concentration of organicnitrogen decreased with decreasing phosphorus supplyand the N : P ratio was lower for B. media than for theother two species, which had similar ratios. Phospho-rus concentration increased in all plant parts withincreasing supply and at the highest rate both D. glom-erata and B. media had very high values. This mightindicate luxury uptake, at least in B. media with a lowrequirement for this element.

Cooper (1976) reported that an ecotype of B. mediacollected from dolomitic limestone was more tolerantto high concentrations of magnesium than ecotypescollected from Carboniferous Limestone. The dolomitic


748J. M. Dixon


population showed a more efficient calcium uptake,and more efficient exclusion and greater tolerance ofhigh tissue magnesium concentration than did the Car-boniferous Limestone population.

Grime & Hodgson (1969) examined the susceptibil-ity of various species to aluminium toxicity and foundB. media to be very susceptible to aluminium; only0.05 m aluminium was required to inhibit rootgrowth in one-week-old seedlings. They commented thatthere is a very close correlation between the relativefrequency of calcicolous plants on soils of pH < 4.5 andsusceptibility to aluminium toxicity: Grime et al. (1988)list the occurrence of B. media in only c. 1% of quadratssampled with soil pH between 4.0 and 5.0.

( )

Phytoecdysteroid compounds, generally accepted asbeing a deterrent to insect predators, are reported asbeing found associated predominantly with the Euro-pean species of the genus Briza. The following com-pounds were reported to be present in the leaves of B.media (greatest amounts) and also in the roots andseeds: ecdysone, 20-hydroxyecdysone, polypodine B,abutasterone, pterosterone and sidisterone (Savchenkoet al. 1998).

VII. Phenology

Grime et al. (1985) commented that initial growth of B.media in spring appeared to rely on expansion of over-wintering leaves. However, new tillers appear in north-ern England around the end of March and by the end ofMay all overwintering leaves are dead and most of theseasons new tillers have been produced. Al-Mufti et al.(1977) noted that the weight of shoot material in B.media remained fairly constant throughout the yearbut showed a temporary increase at the time of flowerproduction in spring, and Mitchley (1988) found verylittle variation in leaf number per tiller, but that theperiod of maximum leaf mortality was June to August,which coincides with flowering.

In northern England, culms start to elongate by theend of April and by the end of May panicles are emerg-ing. Anthesis takes place during mid- to late June andseed is shed during July, August and sometimes Sep-tember The panicles are a purplish-brown duringanthesis, becoming straw-coloured as the caryopsesripen. Germination in the field occurs mainly in Sep-tember and October.

VIII. Floral and seed characters

( )

Reproduction is amphimictic: cleistogamous flowersare not produced. Beddows (1931) reported that B.media set fewer seeds on selfing than any other speciesexamined, while Murray (1974) classed B. media as

completely self-incompatible and noted that the spe-cies has large anthers (2.2–2.5 mm long), producescopious pollen and has the large feathery stigma typi-cal of outbreeders. Knuth (Poll. 3) observed that theanthers of B. media dehisce for the first time early in themorning and for a second time between 6 and 7 pm.

( )

None recorded.

( )

The unit of dispersal is the caryopsis firmly enclosedwithin the lemma and palea; these form a propagulewhich is about 2 mm long and is subrotund, convex onthe outside and concave within. Propagules either dis-articulate individually at maturity (the majority) or ingroups of several florets (usually those at the top of thespikelet) but sometimes an entire panicle branch isshed, with 2–5 spikelets. Many of the spikelets remainintact on the panicle and will probably be freed onlywhen the panicle disintegrates.

A potted tussock of B. media with 53 inflorescenceswas placed on a 1.5-m2 greased polythene sheet at theend of July and left until the end of October 2000. Thenumber of propagules which fell onto this wererecorded and removed. At the end of October, an esti-mated 75% of the propagules were still attached to theparent plant. Of the estimated 25% shed, 15% of thesewere collected between 50 cm and 1 m from the parentplant and only 3% were collected beyond 1 m. This verylow dispersal may reflect the weather conditions duringmost of the period, when it was exceptionally wet andall the inflorescences were waterlogged.

The number of florets for B. media ranges from 4 to9 and occasionally to 12, but most commonly there areseven florets per spikelet. The mean number of inflo-rescences on cultivated plants was 29 and the meanspikelet number 36. Thus taking an average number ofseven florets per spikelet one tussock could theoreti-cally produce in one year 7308 seeds. However, thenumber of inflorescences observed in field specimens ismuch lower.

Ridley (Pl. Disp.) records B. media as being dis-persed in whirlwinds (these normally occur duringJuly–August) either as cut material from hay fields or aswhole plants torn up by the wind.

As the propagule does not possess an awn, and thuslacks a mechanism for drilling it into the soil, germina-tion occurs on the surface.

( ) :

Germination tests on samples of 200 seeds, from abulk gathering in North Yorkshire, after 4 months’ drystorage at room temperature, were carried out in agrowth cabinet with a light flux of 1500 µmol m−2 s−1

over a 12-h day at 20 °C when temperature was not being


749Briza media L.


investigated. Seed freshly harvested in July and placedimmediately on moist filter paper gave 23% ger-mination. After dry storage at room temperature in thelaboratory for 1 month, germination was 30% and after3 months’ storage 86% germination was obtained,showing that a period of after-ripening is beneficial.

Briza media will germinate between 5 °C and 30 °C,with an optimum around 20 °C (86% germination).Germination at 20 °C commenced after 7 days andwas completed in 12. This was not significantlydifferent from germination at 15 °C (79%) where ger-mination commenced after 8 days and was completedin 16. Germination at 25 and 30 °C was significantlylower with only 38 and 35% germination, which com-menced after 6 days at both temperatures and wascompleted in 14 and 20 days, respectively. Germinationat 5 °C was very slow, with germination not startinguntil 2 months after moistening and then occurringvery sporadically over the next 5 months, to give a totalof 55%.

Pre-chilling and freezing for 8 weeks gave 88 and87% germination, respectively, which was not signifi-

cantly different from the untreated control with 86%.Germination with seeds submerged in distilled watergave 81%, while preheating seeds to 40, 60 and 80 °Cgave 90, 81 and 81% germination, respectively. Germi-nation in total darkness was 82% and there was noeffect on the rate of germination.

( )

Hydration of the propagule results in a separation ofthe lemma and palea. The radicle emerges from theproximal end of the grain. Simultaneously the coleop-tile emerges from between the lemma and the palea; itextends to about 8 mm and then splits to reveal the firsttrue leaf. Seedling development is shown in Fig. 2.

IX. Herbivory and disease

( )

Briza media is readily grazed by mammals, particularlycattle, but there are very few records of invertebrate

Fig. 2 Dispersal units and seedlings of Briza media: (a) dry caryopsis – upper left adaxial surface, upper right and lower leftabaxial surface; (b) after imbibition – as for (a); (c) 8 days after germination; (d) after 15 days; (e) after 20 days; (f ) after 30 days.Germination was on moist filter paper, with 14-h days, a day temperature of 20 °C and a night temperature of 16 °C. (a)–(d) tosame scale, and (e) and (f) to same scale.


750J. M. Dixon


grazing. Grime et al. (1968) found that it was unpalat-able to snails and the author has not seen any slug dam-age on plants in cultivation. Briza media is, however,grazed by the following insects: Leptopterna ferrugata(Fallén) (Hemiptera: Miridae) – larval stages; Apameascolopacina (Esper) (Lepidoptera: Noctuidae) – larvaemine stems; Phytomyza nigra Meigen (Diptera:Agromyzidae) – larvae mine stems. Larvae and adultsof the mite Eriophyes tenuis Nalepa (Acari: Eriophyidae)also feed on leaves and flowers of B. media, causing leafrolling and sterility.

( )

The leaves of B. media may be infected by the rustsPuccinia coronata CDA, Puccinia glumarum (Schm.)Erikss. and Henn., and Puccinia graminis Pers., by therust Uromyces brizae GM., E. Mull. and Terr. and bythe smut Ustilago striiformis (West.) Niessel (Vad. para.Pilze). The Ascomycete Pyrenophora trichostoma (Fr.)Fuckel is also recorded from dead stems and sheaths ofBriza media (Ellis & Ellis 1985).

X. History

There is no record of the early postglacial history ofBriza media (Godw. Hist.). The species was firstrecorded by Pena & Lobel (1570) as ‘Phalaris pratensisminor … herbidis pratensis busque. Angliae oritur’(First Rec.).

Acknowledgements

My thanks are due to Dr D. J. Hambler for helpfuladvice and criticism, to Dr L. K. Ward for informationfrom the Phytophagous Insect Data Bank, to S. Davidsonfor drawing Fig. 2 and to Henry Arnold, BiologicalRecords Centre, for preparing Fig. 1. I also thank theEditors and Prof. C. Stace for their valuable commentson the manuscript.

References

Al-Mufti, M.M., Sydes, C.L., Furness, S.B., Grime, J.P. &Band, S.R. (1977) A quantitative analysis of shoot phenologyand dominance in herbaceous vegetation. Journal of Ecology,65, 759–791.

Andersson, F. (1970) Ecological studies in a Scanian wood-land and meadow area, southern Sweden. Opera Botanica,27, 1–190.

Baker, H. (1937) Alluvial meadows: a comparative studyof grazed and mown meadows. Journal of Ecology, 25,408–420.

Balme, O.E. (1953) Edaphic and vegetational zoning on theCarboniferous limestone of the Derbyshire Dales. Journalof Ecology, 41, 331–344.

Beddows, A.R. (1931) Seed setting and flowering in variousgrasses. Welsh Plant Breeding Station, Bulletin H 12.

Benoit, P. & Richards, M. (1961) A contribution to a flora ofMerioneth. Nature in Wales, 7, 147–170.

Birse, E.L. (1980) Scottish plant communities – revised andadditional tables. Bulletin of the Soil Survey, 4. MacaulayInstitute for Soil Research, Aberdeen, UK.

Bosemark, N.O. (1957) Further studies on accessory chromo-somes in grasses. Hereditas, 43, 236–298.

Bradshaw, A.D., Chadwick, M.J., Jowett, D. & Snaydon, R.W.(1964) Experimental investigations into the mineral nutri-tion of several grass species. IV. Nitrogen level. Journal ofEcology, 52, 665–676.

Bradshaw, A.D., Lodge, R.W., Jowett, D. & Chadwick, M.J.(1958) Experimental investigations into the mineral nutritionof several grass species. I. Calcium level. Journal of Ecology,46, 749–757.

Bramwell, D., Humphries, C.J., Murray, B.G. & Owens, S.J.(1971) Chromosome numbers in plants from the CanaryIslands. Botaniska Notiser, 124, 376–382.

Braun-Blanquet, J. (1939) Prodromus der Pflanzengesellschaften.SIGMA, Montpellier, France.

Cooper, A. (1976) The vegetation of Carboniferous limestonesoils in South Wales. II. Ecotypic adaptation in response tocalcium and magnesium. Journal of Ecology, 64, 147–155.

Crackles, F.E. (1990) Flora of the East Riding of Yorkshire.Hull University Press and Humberside County Council,Hull, UK.

Dahl, E. (1998) The Phytogeography of Northern Europe.Cambridge University Press, Cambridge, UK.

Davison, A.W. (1964) Some factors affecting seedling estab-lishment in calcareous soils. PhD Thesis, University of Shef-field, Sheffield, UK.

Davy, A.J. (1980) Biological Flora of the British Isles: Des-champsia cespitosa (L.) P. Beauv. Journal of Ecology, 68,1075–1096.

Dixon, J.M. (1982) Biological Flora of the British Isles:Sesleria albicans Kit. ex Schultes. Journal of Ecology, 70,667–684.

Dixon, J.M. (1991) Biological Flora of the British Isles: Ave-nula (Dumort.) Dumort. Journal of Ecology, 79, 829–865.

Dixon, J.M. (1995) Biological Flora of the British Isles:Trisetum flavescens (L.) Beauv. Journal of Ecology, 83, 895–909.

Dixon, J.M. (2000) Biological Flora of the British Isles:Koeleria macrantha (Ledeb.) Schultes. Journal of Ecology,88, 709–726.

Dony, J.G. (1967) Flora of Hertfordshire. Hitchen UrbanDistrict Council, Hitchen, UK.

Edees, E.S. (1972) Flora of Staffordshire. David & Charles,Newton Abbot, UK.

Ellenberg, H. (1988) Vegetation Ecology of Central Europe,4th edn. Cambridge University Press, Cambridge, UK.

Ellis, M.B. & Ellis, J.P. (1985) Microfungi on Land Plants: AnIdentification Handbook. Croom-Helm, London, UK.

Férnandes, A. & Queiros, M. (1969) Contribution à connais-sance cytotaxonomique des Spermatophyta du Portugal. I.Gramineae. Boletim da Sociedade Broteriana, 43, 20–140.

Frey, L., Mirek, Z. & Mizianty, M. (1977) Contribution to thechromosome numbers of Polish vascular plants. FragmentaFloristica et Geobotanica, 23, 317–326.

Gauld, J.H. & Robertson, J.S. (1985) Soils and their relatedplant communities on the Dalradian limestone of somesites in central Perthshire, Scotland. Journal of Ecology, 73,91–112.

Graham, G.G. (1988) The Flora and Vegetation of CountyDurham. The Durham Flora Committee and DurhamCounty Conservation Trust, Durham, UK.

Grime, J.P. & Curtis, A.V. (1976) The interaction of droughtand mineral nutrient stress in calcareous grassland. Journalof Ecology, 64, 976–998.

Grime, J.P. & Hodgson, J.G. (1969) An investigation of theecological significance of lime-chlorosis by means of large-scale comparative experiments. Ecological Aspects of theMineral Nutrition of Plants (ed. I.H. Rorison), pp. 67–99.Blackwell Scientific Publications, Oxford, UK.

Grime, J.P., Hodgson, J.G. & Hunt, R. (1988) ComparativePlant Ecology. Unwin-Hyman, London, UK.


751Briza media L.


Grime, J.P., Mackey, J.M.L., Hillier, S.H. & Read, D.J. (1987)Floristic diversity in a model system using experimentalmicrocosms. Nature, 328, 420–422.

Grime, J.P., McPherson-Stewart, S.F. & Dearman, R.S.(1968) An investigation of leaf palatability using the snailCepea nemoralis L. Journal of Ecology, 56, 405–420.

Grime, J.P., Shacklock, J.M.L. & Band, S.R. (1985) NuclearDNA contents, shoot phenology and species co-existencein a limestone grassland community. New Phytologist, 100,435–445.

Grose, D. (1957) Flora of Wiltshire. The Natural HistorySection of Wiltshire Archaeological and Natural HistorySociety, Devizes, UK.

Grubb, P.J., Green, H.E. & Merrifield, R.C.J. (1969) Theecology of chalk heath: its relevance to the calcicole-calcifuge and soil acidification problems. Journal of Ecology,57, 175–212.

Harley, J.L. & Harley, E.L. (1987) A check-list of mycorrhizain the British flora. New Phytologist Suppl., 105, 1–102.

Hitchcock, A.S. (1971) Manual of the Grasses of the UnitedStates, Vol. I, 2nd edn. Dover Publications, New York,USA.

Horwood, A.R. & Noel, C.W.F. (1933) Flora of Leicestershireand Rutland. Oxford University Press, London, UK.

Hundt, R. (1958) Beiträge zur Wiesenvegetation Mitteleuropas.I. Die Avenwiesen an der Elbe, Saale und Mulde. Nova ActaLeopoldina, 20, 3–206.

Hyde, H.E. & Wade, A.E. (1957) Welsh Flowering Plants.National Museum of Wales, Cardiff, UK.

Ivimey-Cook, R.B. & Proctor, M.C.F. (1966) The plant com-munities of the Burren, Co. Clare. Proceedings of the RoyalIrish Academy, 64B, 211–301.

Jeffrey, D.W. & Pigott, C.D. (1973) The response of grass-lands on sugar-limestone in Teesdale to applications ofphosphorus and nitrogen. Journal of Ecology, 61, 85–92.

Knapp, G. & Knapp, R. (1953) Über anthropogene Pflan-zengesellschaften im mittleren Tirol. Berichte DeutschenBotanischen Gesellschaften, 66, 393–408.

Korna£, M.J. (1949) Revue systématique et spectres de la bio-logie florale des associations végétales rocheuses du JuraCracovien. Bulletin de l’Academie Polonaise de Sciences,Series B, I, 85–97.

Kota¢ska, M. (1970) Morphology and biomass of the under-ground organs of plants in grassland communities of theOjców National Park. Zaklad Ochrony Przyrody PolskiejAkademii Nauk, 4, 1–107.

Ko∞uharov, S.I., Petrova, A.V. & Stoeva, M. (1974) Cytotax-onomic study on Poaceae V.g. Briza L. Doklady BolgarskoiAkademii Nauk, 27, 383–386.

Lippmaa, T. (1931) Beiträge zur Kenntnis der Flora und Vegeta-tion Süd-west-Estlands. Acta Instituti et Horti BotaniciUniversitatia Tartuensia (Dorpatensia), 2, 1–253.

Lloyd, P.S. (1968) The ecological significance of fire in lime-stone grassland communities of the Derbyshire Dales.Journal of Ecology, 56, 811–826.

Marschall, F. (1947) Die Goldhaferwiese der Schweiz.Beiträge zur Geobotanischen Landesaufnahme der Schweiz,26, 1–168.

McLellan, A.J., Law, R. & Fitter, A.H. (1997) Response ofcalcareous grassland plant species to diffuse competition.Journal of Ecology, 85, 479–490.

Mejstrik, V.K. (1972) Vesicular-arbuscular mycorrhizas ofthe species of a Molinietum coeruleae L.I. Association: theecology. New Phytologist, 71, 883–890.

Meteorological Office (1972) Tables of temperature, relativehumidity, precipitation and sunshine for the world. Part III.Europe and the Azores. Her Majesty’s Stationery Office,London, UK.

Meusel, H. (1940) Die Grasheiden Mitteleuropas Versucheiner vergleichend – pflanzengeographischen Gliederung.Botanisches Archiv, 41, 357–519.

Milnes, K.J., Davies, W.J., Rodwell, J.S. & Francis, B.J. (1998)The responses of Briza media and Koeleria macrantha todrought and re-watering. Functional Ecology, 12, 665–672.

Mitchley, J. (1988) Control of relative abundance of perennialsin chalk grassland in southern England. Journal of Ecology, 76,607–616.

Mitchley, J. & Willems, J.H. (1995) Vertical canopy structureof Dutch chalk grasslands in relation to their management.Vegetatio, 117, 17–27.

Murray, B.M. (1974) Breeding systems and floral biology inthe genus Briza. Heredity, 33, 285–292.

Newton, A. (1971) Flora of Cheshire. Cheshire CommunityCouncil, Chester, UK.

Ní Lamhna, E. (1982) The vegetation of saltmarshes andsand-dunes at Malahide Island, County Dublin. Studies onIrish Vegetation (ed. J. White), pp. 111–129. Royal DublinSociety, Dublin, Ireland.

O’Sullivan, A.M. (1982) The lowland grasses of Ireland. Stud-ies on Irish Vegetation (ed. J. White), pp. 131–142. RoyalDublin Society, Dublin, Ireland.

Oberdorfer, E. (1978) Süddeutsche Pflanzengesellschaften, II.Fischer, Stuttgart, Germany.

Preston, C.D. & Hill, M.O. (1997) The geographical relation-ships of British and Irish vascular plants. Botanical Journalof the Linnean Society, 124, 1–120.

Read, D. & Haselwandter, K. (1981) Observations on themycorrhizal status of some alpine plant communities. NewPhytologist, 88, 341–352.

Reader, R.J., Jalili, A., Grime, J.P., Spencer, R.E. &Matthews, N. (1992) A comparative study of plasticity inseedling rooting depths in drying soil. Journal of Ecology,81, 543–550.

Rodwell, J.S., ed. (1991) British Plant Communities, Vol. 2.Mires and Heaths. Cambridge University Press, Cambridge,UK.

Rodwell, J.S., ed. (1992) British Plant Communities, Vol. 3.Grasslands and Montane Communities. Cambridge Uni-versity Press, Cambridge, UK.

Ryser, P., Verduyn, B. & Lambers, H. (1997) Phosphorusallocation and utilization in three grass species with con-trasting response to N and P supply. New Phytologist, 137,293–302.

Savchenko, T., Whiting, P., Sik, V., Underwood, E., Sarker, S.D.& Dinan, L. (1998) Distribution and identities of phyto-ecdysteroids in the genus Briza (Gramineae). BiochemicalSystematics and Ecology, 26, 781–791.

Schubert, W. (1963) Die Sesleria-varia reichen Pflanzenges-ellschaften in Mitteldeutschland. Feddes Repertorium, 140,71–199.

Sikula, J. (1978) Grasses. Hamlyn, London, UK.Sinker, C.A., Packham, J.R., Trueman, I.C., Oswald, P.H.,

Perring, F.H. & Prestwood, W.V. (1985) Ecological Flora ofthe Shropshire Region. Shropshire Trust for Nature Conserva-tion, Shrewsbury, UK.

Sterner, R. (1922) Flora of South Sweden. GeografiskaAnnaler, 4, 221–444.

Stott, P.A. (1971) A Mesobrometum referable to the sub-association Mesobrometum Seslerio-Polygaletosum Tüxendescribed for the Somme Valley. Vegetatio, 23, 61–70.

Thompson, K. & Grime, J.P. (1979) Seasonal variation in theseed banks of herbaceous species in ten contrasting habitats.Journal of Ecology, 67, 893–921.

Tornadore, N., Popova, M. & Gabari, F. (1974) Numericromosomici per la Flora Italiana. Informatore BotanicoItaliano, 6, 43–54.

Tsvelev, N.N. (1984) Grasses of the Soviet Union. RussianTranslation Series. A.A. Balkema, Rotterdam, Netherlands.

Watt, A.S. (1974) Senescence and rejuvenation in ungrazedchalk grassland (Grassland B) in Breckland: the signific-ance of litter and of moles. Journal of Applied Ecology, 11,1157–1171.


752J. M. Dixon


van der Werf, A., van Nuenen, M., Visser, A.J. & Lambers, L.(1993) Effects of N-supply on the rates of photosynthesisand shoot and root respiration of inherently fast- andslow-growing monocotyledonous species. PhysiologiaPlantarum, 89, 563–569.

Wheeler, B.D. (1980) Plant communities of rich-fen systemsin England and Wales. II. Communities of calcareous mires.Journal of Ecology, 68, 405–420.

Willems, J.H. (1973) Observations on north-west Europeanlimestone grassland vegetation. I. Limestone vegetation inthe central part of the French Jura, south of Champagnôle(Department Jura). Koninklijke Nederlandse Akademie vanWetenschappen, Amsterdam, Proceedings, Series C, 76, 231–244.

Willems, J.H. (1980) Observations on north-west Europeanlimestone grassland communities. V,a An experimental

approach to the study of species diversity and above-groundbiomass in chalk grassland. Koninklijke Nederlandse Akad-emie van Wetenschappen, Amsterdam, Proceedings, SeriesC, 83, 279–306.

Willems, J.H. (1982) Phytosociological and geographicalsurvey of Mesobromion communities in western Europe.Vegetatio, 48, 227–240.

Willems, J.H., van Delft, J.M.E. & de Rijke, M.K. (1981)Observations on north-west European limestone grasslandcommunities. IV. Phytosociological notes on chalk grass-lands in Denmark. Folia Geobotanica et PhytotaxonomicaBohemoslovaca, 16, 391–406.

Willis, A.J., Folkes, B.F., Hope-Simpson, J.F. & Yemm, E.W.(1959) Braunton Burrows: the dune system and its vegeta-tion. Part II. Journal of Ecology, 47, 249–288.


Documents

Briza media L