Mycelis muralis (L. ) Dumort. (Lactuca muralis (L. ) Gaertner)

Gerard Clabby; Bruce A. Osborne

Question: Which factors determine diversity of native and alien vascular plant species in semi-natural dry grasslands?Location: Northern limestone Alps to the southern rim of the Bohemian massif in northern Austria.Methods: In 70 randomly chosen dry grassland patches (0.008 ha - 7 ha) we sampled a complete inventory of vascular plant species at each site. We analysed the correlation between species diversity of natives, archaeophytes (pre-1500 aliens) and neophytes (post-1500 aliens). We used GLM to study the relationship of species number (natives, neophytes, archaeophytes) to five explanatory variables (altitude, within habitat diversity, habitat diversity of adjacent areas, within land-use diversity and land-use in adjacent areas). Orthogonal components of these variables were derived with a PCA and used in the models. We also tested the influence of minimum residence time (MRT) and the covariables origin, mode of introduction and life form on the number of grassland sites with neophytes with analogous GLMs.Results: Native species diversity species was positively correlated with the species diversity of new, but not old invaders. GLM explains 70% of the variance in the number of native species. Patch size explained the largest part of the variation in the number of native species. PCA axes 1 and 3 were significantly related to the number of native species. Axis 1was related to on-site habitat and land-use diversity. The GLM of the archaeophyte diversity explains 18% of the variance. Altitude and presence of fields and grassland in the neighbourhood mainly explained archaeophyte species diversity. The GLM of neophyte diversity explains 12% of the variance. The number of neophytes was positively related to that of archaeophytes. Only PCA axis 3, which is mainly influenced by adjacent land-use types, showed a relationship with neophytes. MRT, mode of introduction and region of origin (but not life form) were significantly related to the number of grassland sites invaded by neophytes, explaining 35% of the variance.Conclusion: Most factors governing native species diversity are not significantly related to alien species diversity. Additional determinants of the local scale diversity of alien species exist such as region of origin and historical factors (MRT, mode of introduction).

1. This account presents information on all aspects of the biology of Crataegus laevigata (Poir.) DC (Midland hawthorn) (C. oxyacanthoides Thuill.) that are relevant to understanding its ecological characteristics and behaviour. The main topics are presented within the standard framework of the Biological Flora of the British Isles: distribution, habitat, communities, responses to biotic factors, responses to environment , structure and physiology, phenology, floral and seed characters, herbi-vores and disease, history and conservation. 2. Crataegus laevigata is primarily a shade-tolerant shrub or small tree up to 12-m tall of ancient woodlands (of which it is an indicator plant) and occasionally old hedges, usually on heavy clay soils and avoiding limestone and chalk. It is native to central and northern Europe and in the British Isles is native to southeast England, occurring naturally up to the Midlands, hence the common name. It is largely absent naturally from Scotland, Wales and Ireland. 3. Flowers usually have two styles, varying from (rarely) 1 to 5 with an equal number of pyrenes in the fruit, differentiating it from C. monogyna with usually one style and pyrene. Pollination is by insects and fruit are dispersed primarily by birds. Fruit has traditionally been used for food, and with the leaves and flowers have a long tradition in herbal medicine. 4. Disturbance and fragmentation have allowed C. monogyna to permeate into old woodlands and hybridise with C. laevigata. These two species are inter-fertile and barriers to hybridisation are primarily spatial separation thus allowing extensive introgression such that in many parts of Europe, pure C. laevigata is becoming scarce. K E Y W O R D S conservation, geographical and altitudinal distribution, germination, mycorrhiza, parasites and diseases, pharmaceuticals, reproductive biology, soils

Journal of Ecology 0888\ 76\ 045Ð061 BIOLOGICAL FLORA OF THE BRITISH ISLES NO[ 193 List Br[ Vasc[ Pl[ "0847# no[ 440\ 0 Mycelis muralis "L[# Dumort[ "Lactuca muralis "L[# Gaertner# List[ Br[ Vasc[ Pl[ "0847# 440\ 0 GERARD CLABBY$ and BRUCE A[ OSBORNE Department of Botany\ University College Dublin\ Bel_eld\ Dublin 3\ Ireland A perennial hemicryptophyte with a basal rosette of three to eight overwintering leaves arising from a root! stock[ Erect leafy stem up to c[ 0 m high\ terminating in a much branched panicle with many capitula[ Older rootstocks occasionally producing more than one rosette of leaves and erect stem per plant[ Leaves light green in summer and dark green in winter in shaded locations\ with or without redÐcrimson undersides[ In more open habitats undersides of leaves usually crimson\ but entire leaves and other above!ground parts may also be crimson[ Leaves lobed\ 39Ð119 mm long\ 19Ð024 mm wide\ glabrous[ Rosette leaves and leaves on lower portion of erect stem lyrate!pinnati_d with a ~ange of the leaf blade of variable width con! necting individual lobes[ Capitula 8Ð04 mm across "Mej(as 0883^ Stace 0886#\ usually with _ve ligulate ~orets^ capitula borne in a large open panicle[ Invo! lucre 6Ð09 mm\ narrowly cylindrical\ inner bracts linear\ outer bracts very small and spreading "Fl[ Eur[ 3^ Clapham et al[ 0876#[ Florets yellow and glabrous[ Achene black or sometimes brown\ 2Ð3 mm long including pale short\ slender beak\ 9[8 mm wide\ with pappus of white simple hairs in two unequal rows\ c[ 4[4 mm in length^ achene weight 9[23 mg "Fl[ Eur[ 3^ Clapham et al[ 0876^ Grime et al[ 0877#[ Plants self! fertile "Mej(as 0883#[ Although evidence for population di}erentiation has not been published\ screening of plants from open limestone pavement in the Burren\ Co[ Clare\ Ireland\ and from woodland near Durrow\ Co[ Laois\ Ireland\ using random ampli_ed polymorphic "RAPD# pri! mers "C[ Kavanagh\ T[ Gallagher + B[A[ Osborne\ unpublished data# indicates genetic di}erences between these two populations[ The two populations could also be separated on the basis of leaf antho! cyanin content\ but not when a number of pho! tosynthetic and related traits were used "G[ Lanigan\ B[ A[ Osborne + G[ Clabby\ unpublished data#[ 045 Abbreviated references are used for many standard works\ see Journal of Ecolo`y "0864#\ 52\ 224Ð233[ Nomenclature of vascular plants follows Flora Europaea and\ where di}erent\ Stace "0886#[ $Correspondence] G[ Clabby "fax ¦242 0 6950042^ e!mail gerry[clabbyÝucd[ie#[ Native in Britain but doubtfully native in Ireland[ Generally a plant of shaded places including wood! lands\ wood margins\ scrub\ walls and rock outcrops[ In Ireland reaches its greatest abundance on open limestone pavement in the Burren[ I[ Geographical and altitudinal distribution Mycelis muralis occurs in over 869 09!km squares in Ireland and Britain out of a total of c[ 2799 "Fig[ 0#[ Widespread in England and Wales\ with a more sparse distribution in Ireland and Scotland "Fig[ 0#[ Absent from Shetland\ Orkney\ the Outer Hebrides and the Channel Islands "Clapham et al[ 0876#[ Although geo! graphically widespread\ it is typically uncommon and localized[ In Ireland it has almost certainly been intro! duced in all locations except perhaps the Burren\ Co[ Clare "Clabby + Osborne 0883#[ In the Burren lack of early records has given rise to debate about its status there "Webb 0851^ Webb + Scannell 0872^ Clabby + Osborne 0883#[ The altitudinal range in Britain extends from sea level to 346 m at High Cup Nick "Alt[ range Br[ Pl[#[ In Ireland it has been recorded from sea level to altitudes up to 299 m in the Burren "Clabby + Osborne 0883#[ In Ireland "Clabby + Osborne 0883# and Scotland "J[H[ Dickson\ per! sonal communication# it is increasing[ Its status in England and Wales is uncertain but it is not under threat "Grime et al[ 0877#[ It is present throughout most of temperate con! tinental Europe\ with a distribution centred on central and southern regions "Fig[ 1^ Fl[ Eur[ 3#\ and may be classi_ed phytogeographically as a European tem! perate species "Preston + Hill 0886#[ It is more spar! sely distributed in Scandinavia\ parts of the Russian Federation and western parts of the Iberian peninsula "Fl[ Eur[ 3^ Atl[ Fl[ Eur[^ Fitter 0867^ Ellenberg 0877#[ Its northernmost European location is in Norway at c[ 57[4 >N "Clapham et al[ 0876#[ It is absent from the Azores\ the Balearic Islands\ Crete\ the Faroe Islands\ Iceland\ Portugal\ the Russian Federation approxi! mately north of latitude 59 >N and the islands of Spitsbergen\ Bjornnoya and Jan Mayen "Fl[ Eur[ 3#[ In the Swiss canton of Wallis "Valais# it has been 046 G[ Clabby + B[A[ Osborne Fig[ 0 The distribution of Mycelis muralis in Britain and Ireland[ Each dot represents at least one record in a 09!km square of the National Grids[ Mapped by Mrs J[ M[ Croft\ Environmental Information Centre\ Institute of Terrestrial Ecology\ mainly from records collected by members of the Botanical Society of the British Isles and in Ireland chie~y from records given by Clabby + Osborne "0883#[ "# Pre!0849^ "ž#0849 onwards[ Þ 0888 British Ecological Society\ Journal of Ecology\ 76\ 045Ð061 documented at an altitude of 0799 m "Hegi Fl[ ed[ 0\ 0# and in Turkey up to 0599 m "Davis 0864#[ In the Polish Carpathian Mountains it reaches an altitude of 839 m and is most abundant above 599 m "Zarzycki 0865#[ Mycelis muralis also occurs in North Africa\ includ! ing Algeria "Quezel + Santa 0852# and Morocco where it is found up to 0399 m "Jahandiez + Maire 0823#[ It also occurs in the Caucasus where it reaches an altitude of 1299 m "Fl[ URSS 18#[ Mycelis muralis has been introduced in North America "Gleason + Cronquist 0852# and now occurs in the Atlantic\ Cordilleran and Paci_c phyto! geographic regions "Klinka et al[ 0878#[ It is also pre! sent in New Zealand on Stewart Island\ from Coro! mandel southwards on the North Island and throughout the South Island "Webb et al[ 0877#[ II[ Habitat In continental Europe M[ muralis is a woodland spec! ies most commonly found in open woods\ wood mar! gins and woodland clearings "Ellenberg 0877#\ occur! ring to a lesser extent in scrub\ on walls\ rock outcrops 047 Mycelis muralis "L[# Dumort[ Fig[ 1 The Northern hemisphere distribution of Mycelis muralis[ Hatched areas indicate regions where the species is fairly common to common[ Dots indicate isolated occurrences\ and areas bounded by a line indicate regions for which precise data are not available[ Amended from Hulten "0875#[ and montane habitats "Hegi Fl[ ed[ 0\ 0^ Fl[ URSS 18^ Fl[ Eur[ 3#[ In Britain and Ireland M[ muralis is also found in open woods\ wood margins and scrub but is also locally common on natural rock outcrops and on walls[ "A# CLIMATIC AND TOPOGRAPHICAL LIMITATIONS Þ 0888 British Ecological Society\ Journal of Ecology\ 76\ 045Ð061 The temperate distribution of M[ muralis suggests intolerance of climatic extremes[ Its northern limit in Europe follows approximately the Ð 6 >C mean Jan! uary isotherm\ and its southern limit in Europe and adjacent North Africa follows approximately the 14 >C mean July isotherm "Wallen 0869#[ In addition\ in Europe\ North Africa and the Caucasus\ M[ muralis occurs in areas with an average annual rainfall of 499 mm or above "Wallen 0869# and this may be a factor in setting southern and eastern distribution limits[ In western Europe it does not seem possible to attribute the sparse occurrence of M[ muralis in Ireland\ Scotland and the Iberian peninsula to any simple climatic variables[ The recent and ongoing increase of M[ muralis in Ireland and Scotland sug! gests that it has not yet completed its north!westward migration after the last glaciation\ and this may also explain its absence from Iceland and western parts of the Iberian peninsula[ Alternatively this could re~ect climatic and land!use changes in recent decades[ Typically\ M[ muralis is a plant of shaded or semi! shaded locations\ such as open woodland\ woodland clearings and margins\ throughout its range "Fl[ URSS 18^ Jahandiez + Maire 0823^ Quezel + Santa 0852^ Ellenberg 0877^ Grime et al[ 0877^ Webb et al[ 0877^ Klinka et al[ 0878^ Clabby + Osborne 0883#[ These habitats may often be associated with natural or anthropogenic disturbance such as storms and _res\ clear!felling\ etc[ Mycelis muralis is also found in open habitats such as limestone pavement in the Burren\ Co[ Clare\ Ireland or\ for example\ as part of the weedy ~ora of small\ non!forested islands in Barkley Sound\ Vancouver Island\ British Columbia\ Canada[ In Ireland and Britain it also occurs in _s! sures in limestone pavement "grikes# and is most com! mon in shallow grikes or above a depth of 099 cm in deeper grikes "Silvertown 0871\ 0872^ Clabby 0881#[ In Britain M[ muralis appears to be con_ned to grikes in limestone pavement habitats "Silvertown 0871\ 0872#[ Microclimatically\ grikes may resemble wood! land edge environments where plants are subject to 048 G[ Clabby + B[A[ Osborne comparable changes in light level\ temperature and humidity and this could account\ in part\ for this distribution[ In the She.eld area of Britain\ M[ muralis is most frequent on shaded north!facing slopes "Grime et al[ 0877#[ In Ireland it is most frequent on north!facing walls "Clabby + Osborne 0883#\ although this does not seem to be the case in south!eastern Britain "R[ Payne\ personal communication#[ Mycelis muralis occurs predominantly on north! or south!facing slopes in north!western parts of the Carpathian mountains "Zarzycki 0865#[ Mycelis muralis does not appear to be adversely a}ected by exposure to wind as it is widespread on the windswept limestone pavements of the Burren\ and the Aran Islands\ western Ireland[ "B# SUBSTRATUM Mycelis muralis grows on a range of base!rich sub! strata in Ireland\ Britain and continental Europe\ including mineral soils and a number of skeletal sub! strates such as limestone pavements and walls[ In woodland M[ muralis is typically found over brown earth soils and rendzinas\ which are often base!rich and calcareous throughout "Ellenberg 0877^ Rodwell 0880^ Clabby + Osborne 0883#[ These soils are nor! mally rich in invertebrates and lumbricid worms\ with rapid incorporation of leaf litter which produces a mull humus "Rodwell 0880#[ In some places M[ muralis occurs on more acidic brown earth soils but only where base!rich conditions are maintained "Ellenberg 0877^ Rodwell 0880#[ On limestone pave! ment and walls\ plants are usually rooted in a variable base!rich substrate derived from the parent material\ wind!blown debris and organic matter "Clabby + Osborne 0883#[ Mycelis muralis occurs mainly on free! draining soils that may be seasonally ~ooded "Rodwell 0880^ Clabby 0881#[ Distribution data and Al sensitivity "Rode + Runge 0880# suggest that M[ muralis is a calcicole[ Despite this\ M[ muralis occurs on soils over a wide range of pH values in Ireland and Britain "Table 0^ Grime et al[ 0877# and in Poland on woodland soils with a pH ranging from 2[4 to 6[9 "Czarnecka 0875#[ This may indicate the presence of locally adapted edaphic populations[ Soils from woodland sites\ limestone pavement and walls in Ire! land and Britain had a variable range of mineral nutri! ent contents\ although they were generally base!rich "Table 0#[ Czarnecka "0875# reports M[ muralis from woodland soils in Poland with 9Ð03) humus or organic matter and with variable mineral nutrient contents[ III[ Communities Þ 0888 British Ecological Society\ Journal of Ecology\ 76\ 045Ð061 Mycelis muralis occurs mainly in beech or related woodland types "class QuercoÐFagetea# and in wood! land clearings "class Epilobietea angustifolii# and margins "class Artemisetea vulgaris# in Europe "Ober! dorfer 0867\ 0872^ Ellenberg 0877#[ It also occurs less frequently on basic rocks and on walls "class Asplen! ietea rupestria# "Oberdorfer 0866^ Ellenberg 0877^ Clabby + Osborne 0883^ A[J[C[ Malloch\ personal communication#[ The following account details occurrences in woodland and related vegetation types and then addresses other communities in which M[ muralis is found[ In Ireland M[ muralis occurs in woodland com! munities in the CoryloÐFraxinetum "Clabby + Osborne 0883# in the alliance AlnoÐUlmion and the order Fagetalia "sensu Ellenberg 0877#[ The CoryloÐ Fraxinetum corresponds broadly to the DryopteridoÐ Fraxinetum phyllitidetosum of Klotzli "0869#\ which corresponds in part with the Geranium robertianum subcommunity of the British Fraxinus excelsiorÐAcer campestreÐMercurialis perennis woodlands "NVC code W7# "Rodwell 0880#[ In Britain there are two woodland types on base! rich calcareous soils in which M[ muralis occurs fre! quently] the FraxinusÐAcerÐMercurialis woodlands "NVC W7# and the Fa`us sylvaticaÐMercurialis per! ennis woodlands "NVC W01# "Rodwell 0880#[ In W7 woodlands M[ muralis occurs most commonly with low frequency and with low cover values in the Hedera helix subcommunity "W7d#\ the Geranium rob! ertianum subcommunity "W7e# and the Teucrium sco! rodonia subcommunity "W7g#[ Constant species in W7 woodlands include Acer campestre\ Corylus avel! lana\ Eurhynchium praelon`um\ Fraxinus excelsior\ Mercurialis perennis and Rubus fruticosus agg[ Other species common in the _eld layer include Circaea lut! etiana\ Dryopteris _lix!mas\ Geum urbanum and Hya! cinthoides non!scripta\ and in the ground layer Bra! chythecium rutabulum and Pla`iomnium undulatum[ In the Yorkshire dales the Geranium robertianum sub! community occurs in grikes in the limestone pavement with a greater range of ferns\ including Dryopteris submontana "D[ villarii# and Polystichum lonchitis "Rodwell 0880#[ In W01 woodlands\ M[ muralis occurs in the Mercurialis perennis subcommunity "W01a#\ the Sanicula europaea subcommunity "W01b# and the Taxus baccata subcommunity "W01c#\ all of which occur in southern England[ The constant spec! ies in W01 woodlands are Fa`us sylvatica and Mer! curialis perennis[ The _eld layer is qualitatively similar to the _eld layer of the W7 woodlands and frequently includes species such as Circaea lutetiana\ Geum urbanum and Sanicula europaea[ Bryophytes are infrequent\ with the most common being Bra! chythecium rutabulum and Eurhynchium praelon`um[ In phytosociological terms these woodland com! munities could be included in the alliances Carpinion betuli "W7#\ TilioÐAcerion "W7# or Fagion sylvaticae "W01#\ in the order Fagetalia[ Mycelis muralis also occurs infrequently in the Hedera helixÐUrtica dioica and the Viburnum lantana subcommunities of Cra! tae`us mono`ynaÐHedera helix scrub "NVC W10a 059 Mycelis muralis "L[# Dumort[ Þ 0888 British Ecological Society\ Journal of Ecology\ 76\ 045Ð061 Table 0 Chemical characteristics of soil sampled from Mycelis muralis sites in Ireland and Britain[ Soils were from 9 to 09 cm depth[ Dried soils were extracted for cations using either 1[4) v:v acetic acid "$# or concentrated nitric acid "#\ and Ca\ Mg\ K\ Na determined using ~ame emission or atomic absorption spectrophotometry as appropriate[ N was determined using the method of Hendershot "0874# and P determined using Murphy + Riley|s "0851# reagent following sulphuric acid digestion using a micro! Kjeldahl procedure "Hendershot 0874#[ Data are expressed as mg gÐ0 with the standard deviation in parentheses "n 2# Location Habitat Grid reference Mullach Mor\ Co[ Clare\ Ireland$ Limestone pavement R259874 Mullach Mor\ Co[ Clare\ Ireland$ Woodland R219834 Durrow\ Co[ Laois\ Ireland$ Woodland S281678 Durrow\ Co[ Laois\ Ireland Walls S281678 Narborough\ Norfolk\ UK Woodland TF649007 and W10d\ respectively#\ a community of neutral to base!rich soils common throughout lowland Britain[ It also occurs occasionally in communities that develop over base!poor and often moist brown soils\ such as the typical subcommunity of Fraxinus excel! siorÐSorbus aucupariaÐMercurialis perennis woodland "NVC W8a#\ the Hedera helix subcommunity of Quer! cus roburÐPteridium aquilinumÐRubus fruticosus woodland "NVC W09c#\ and the Blechnum spicant subcommunity of Quercus petraeaÐBetula pubescensÐ Oxalis acetosella woodland "NVC W00b#[ In continental Europe M[ muralis occurs most often in communities in the order Fagetalia and the alliance Fagion sylvaticae\ although it also occurs in the alliances TilioÐAcerion and Carpinion betuli "Ellen! berg 0877#[ In the Fagion\ Ellenberg "0877# dis! tinguishes four suballiances\ all of which contain associations in which M[ muralis occurs[ These include montane to submontane pure beech woods in the LuzuloÐFagion "association LuzuloÐFagetum#\ which are found from Switzerland to southern Sweden and from the Ardennes to the Carpathians[ In the Galio odoratiÐFagion M[ muralis occurs in several associations including the Galio odoratiÐFag! etum "or montane limestone _r beech woods# typical of the Vosges\ the Sudeten mountains\ the Bavarian forest\ the eastern Black forest\ the north!west Swab! ian Jura\ the Alps and the mountains of Croatia and Slovenia\ the Dentario glandulosaeÐFagetum in the Polish Carpathians "Zarzycki 0865^ Czarnecka 0875#\ and the MelicoÐFagetum in central Europe "Ellenberg 0877#[ In the Polish Carpathians M[ muralis also occurs in the CariciÐFagetum "Zarzycki 0865# or dry! slope beech woods in the suballiance CephalantheroÐ Fagion[ Mycelis muralis is also found in silver!_r "Abies alba# woods\ which occur extensively on the Balkan peninsula and the Swiss Alps and are assigned to the suballiance Galio rotundifoliiÐAbietion "Ellen! berg 0877#[ Typical associations include the QuercoÐ pH N P 6[03 02[16 0[07 "9[11# "0[62# "9[18# 5[09 05[49 0[23 "9[22# "9[07# "9[90# 4[42 2[63 9[70 "9[42# "9[39# "9[97# 6[1 0[39 9[49 "9[99# "9[00# "9[95# 6[72 0[84 9[38 "9[95# "9[08# "9[93# Ca Mg K 079[57 "70[00# 17[49 "4[15# 1[75 "9[53# 06[93 "9[02# 03[90 "9[57# 0[87 "0[12# 9[70 "9[98# 9[13 "9[90# 5[42 "9[96# 9[77 "9[92# 9[02 "9[92# 9[17 "9[91# 9[01 "9[91# 1[31 "9[10# 0[96 "9[91# Na 9[03 "9[91# 9[01 "9[994# 9[00 "9[90# 0[22 "9[22# 0[95 "9[97# Abietetum in the outer Alps and the Abietetum albae\ typical of the transition zone between the northern central Alps and the dry central valleys "Ellenberg 0877#[ A recent account of Austrian plant com! munities "Mucina et al[ 0882# also lists M[ muralis among the dominant and constant companion species in the {diagnostic species combination| for many associations in the alliance Fagion sylvaticae[ In the alliance TilioÐAcerion\ M[ muralis is found in the PhyllitidoÐAceretum in Poland "Zarzycki 0865# and in the ScolopendrioÐFraxinetum\ the AcerÐCar! pinetum and the Asperulo tauriiÐTilietum in Austria "Mucina et al[ 0882#\ and in the association TilioÐ Carpinetum in the alliance Carpinion betuli "Czarnecka 0875#[ In Austria\ Mucina et al[ "0882# distinguish another alliance\ the AremonioÐFagion\ and list M[ muralis in the Lamio orvalaeÐFagetum\ the Anemono trifoliaeÐFagetum and the Polysticho lonchitisÐFagetum[ In the montane spruce woods of the central Swiss Alps\ on more acidic soils\ M[ muralis occurs in the GalioÐAbietetum\ which may be assigned to the order Fagetalia and in the MelicoÐPiceetum\ an association of dry continental valleys in the order VaccinioÐPicee! talia "class VaccinioÐPiceetea# "Ellenberg 0877#[ Sol! datenkova "0871# described M[ muralis from a spruce grove "PiceetumÐHylocomiosum# near Moscow and M[ muralis also occurs in the VaccinioÐPiceetea in the Polish Carpathians in associations such as the Querco roborisÐPinetum and Abietetum polonicum "Zar! zycki 0865^ Czarnecka 0875#[ Mycelis muralis is common in many woodland clearing communities in the class Epilobietea angu! stifolii\ in the alliances Epilobion angustifolii\ Atro! pion and the SambucoÐSalicion capreae "Oberdorfer 0867#[ Mycelis muralis is also frequent in the closely related woodland margin communities in the alliance Alliarion "of which it is a character species# in the class Artemisietea vulgaris\ and is particularly common in 050 G[ Clabby + B[A[ Osborne Þ 0888 British Ecological Society\ Journal of Ecology\ 76\ 045Ð061 the association EpilobioÐGeranietum robertiani that occurs at woodland edges\ around rocks\ walls and at the entrances to caves "Oberdorfer 0872^ Mucina et al[ 0882#[ In coastal British Columbia\ Canada\ M[ muralis often occurs in similar communities in open forest\ forest edges and on cut!over or burnt sites with species such as Achlys triphylla "Sm[# DC[\ Chamerion an`ustifolium\ Kindber`ia ore`ana "Sullivant# Ochyra\ Polystichum munitum and Tiarella trifoliata L[ "Klinka et al[ 0878#[ Similarly\ in the Barkley Sound region of Vancouver Island M[ muralis occurs in open habitats on small non!forested islands and around the periphery of larger forested islands "Cody + Overton 0885#[ Mycelis muralis also occurs in rock crevice and wall communities in the class Asplenietea rupestria[ Oberdorfer "0866# lists M[ muralis in three rock crev! ice communities\ the DraboÐHieracietum humilis in the Schwabische Alb\ the Cardaminopsietum petraea in the Franconian Jura and the Gymnocarpietum rob! ertiani\ a pioneer community of moist calcareous screes in the Jura[ This community also occurs locally in Britain "NVC OV27\ Gymnocarpium robertianumÐ Arrhenatherum elatius community# in patchworks of grassland\ scrub and woodland on screes and rocky limestone slopes "A[J[C[ Malloch\ personal com! munication#[ These communities are often placed in the order Potentilletalia caulescentis and the alliance Potentillion caulescentis\ which contain vegetation of limestone rocks and walls "Oberdorfer 0866^ Ellen! berg 0877#[ A recent treatment places the Gym! nocarpietum robertiani in the alliance Stipion cal! amagrostis\ which includes fern assemblages of base! rich screes in the submontane and montane zones of central Europe and Scandinavia "Jarol(mek et al[ 0886#[ In Britain\ in situations where there is no graz! ing\ OV27 is often quickly replaced by scrub or wood! land\ although M[ muralis and other species such as Geranium robertianum\ Mercurialis perennis and Viola riviniana can persist in abundance under the trees "A[J[C[ Malloch\ personal communication#[ The com! munity is more frequent on rocky limestone slopes and outcrops where woodland development is patchy and it may sometimes be found in the Teucrium sub! community of the FraxinusÐAcerÐMercurialis wood! land "NVC W7g#[ On such rocky limestone slopes OV27 may often be a secondary community following woodland clearance\ and the Asplenium trichomanesÐ A[ ruta!muraria community "NVC OV28# may also occur in the vegetation mosaic[ Mycelis muralis is also found infrequently in this community\ which is characteristic of sunny crevices in lime!rich bedrocks and walls at low to moderate altitudes\ occurring par! ticularly in western Britain "A[J[C[ Malloch\ personal communication#[ OV28 corresponds to the association Asplenietum trichomanoÐrutaeÐmurariae and in Ireland M[ muralis occurs commonly in this community on walls with species such as Asplenium ruta!muraria\ A[ trich! omanes\ Cymbalaria muralis and Homalothecium ser! iceum "Clabby + Osborne 0883#[ On fully exposed limestone pavement in the Burren\ Co[ Clare\ Ireland\ M[ muralis occurs with species such as A[ ruta!mura! ria\ Ceterach of_cinarum\ Geranium robertianum\ Hedera helix\ Prunus spinosa\ Senecio jacobaea\ Ses! leria caerulea\ Teucrium scorodonia and Thymus poly! trichus[ Ivimey!Cook + Proctor "0855# refer to this community as the Ceterach of_cinarumÐAsplenium trichomanes association\ which probably corresponds to the association Asplenietum trichomanoÐrutaeÐ murariae "White + Doyle 0871#[ The Asplenietum has generally been placed in the alliance Potentillion caulescentis\ although some authors follow Segal "0858# and place it in the CymbalarioÐAsplenion "White + Doyle 0871#[ In the Burren\ M[ muralis also occurs in grikes with species such as Asplenium ruta! muraria\ Geranium robertianum and Phyllitis sco! lopendrium "Osborne + Clabby 0880# and in York! shire with a range of species including Allium ursinum\ Asplenium trichomanes\ Epilobium montanum\ Ger! anium robertianum\ Mercurialis perennis\ Oxalis ace! tosella\ Phyllitis scolopendrium\ Stachys sylvatica and Urtica dioica "Silvertown 0872#[ In shaded crevices and on ledges of lime!rich bedrocks in western and northern Britain\ M[ muralis occurs in the Asplenium virideÐCystopteris fra`ilis community "NVC OV39# "A[J[C[ Malloch\ personal communication#[ This community corresponds to the AsplenioÐCys! topteridetum\ which has generally been placed in the alliance Cystopteridion fragilis "Ellenberg 0877#[ Segal "0858# placed similar vegetation from walls in the Austrian and French mountains in a new associ! ation\ the Polysticho lonchitisÐAsplenietum viridis in the alliance CymbalarioÐAsplenion\ which has been followed by White + Doyle "0871# although M[ muralis has not been recorded from this vegetation type in Ireland[ Mycelis muralis is also found on walls dominated by Hedera helix\ Sambucus ni`ra and Sta! chys sylvatica in Ireland and at wall bases\ with species such as Acer pseudoplatanus\ Circaea lutetiana\ Frax! inus excelsior\ Geranium robertianum\ Hedera helix\ Heracleum sphondylium\ Poa annua\ Sambucus ni`ra and Urtica dioica "Clabby + Osborne 0883#[ In Britain\ M[ muralis occurs infrequently in a range of other communities\ most notably the Arrhen! atherum elatius grasslands "NVC MG0# "A[J[C[ Malloch\ personal communication#\ which may re~ect an ability to colonize disturbed\ open sites on base! rich substrates[ IV[ Response to biotic factors "A# GRAZING The exclusion of cattle from a woodland in Durrow\ Co[ Laois\ Ireland\ led to an increase in the population size of M[ muralis\ which suggests that plants may be susceptible to grazing[ There was little or no indi! 051 Mycelis muralis "L[# Dumort[ cation of an e}ect of grazing by large mammals on the depth distribution of M[ muralis in grikes in limestone pavement in Yorkshire "Silvertown 0871\ 0872#[ In the Burren\ Co[ Clare\ Ireland\ there is no evidence of cattle or goat grazing of M[ muralis[ In high!light habitats large concentrations of anthocyanins in leaves and stems may possibly discourage grazing ani! mals[ In wall habitats grazing by large mammals is e}ectively avoided owing to location[ There is no information on the extent of insect herbivory on M[ muralis[ "B# COMPETITIVE ABILITY There is no experimental evidence on the competitive ability of M[ muralis[ In high!light habitats M[ muralis almost always occurs as a component of a sparse vegetation cover and rarely in a closed sward[ Its occurrence ranges from weedy\ disturbed\ ephemeral habitats "Grime et al[ 0877^ Clabby + Osborne 0883^ Cody + Overton 0885#\ to a presence in long estab! lished\ stable\ open habitats such as old walls or lime! stone pavement with many available microsites for colonization "Clabby + Osborne 0883#[ In many shaded locations M[ muralis is often found in sparse vegetation\ for example on walls or in disturbed mic! rosites in woodland:scrub or along woodland paths and rides[ Mycelis muralis also occurs in closed wood! land ~oor vegetation where it may compete with co! occurring species "Clabby + Osborne 0880#[ "C# RESPONSES TO CULTURAL TREATMENTS Þ 0888 British Ecological Society\ Journal of Ecology\ 76\ 045Ð061 In spruce forest in Waldviertel\ Lower Austria\ the addition of fertilizer and lime\ combined with the removal of litter\ led to the appearance of M[ muralis in the ground layer with other species including Athy! rium _lix!femina\ Poly`onatum verticillatum and Urt! ica dioica "Leitgeb 0883#[ In the Hanoverian Munden\ in an experiment in which beech woodland "LuzuloÐ Fagetum# plots were fertilized with various com! binations of calcium\ potassium and phosphorus\ or {cultivated| prior to the addition of nutrients\ M[ muralis appeared with a range of herbs typical of the more nutrient!rich MelicoÐFagetum "Grabherr 0831 cited by Ellenberg 0877#[ Ellenberg "0877# also describes an experiment in which M[ muralis appeared "with Galeopsis pubescens Besser and Galium odo! ratum# in the ground ~ora of a typical herb!free beech wood "Fagetum nudum in the CephalantheroÐ Fagion# in response to the cutting of beech roots in the upper soil layers[ As these woods are very dry the appearance of M[ muralis may have been due to increased water or nutrient availability as a result of root cutting and subsequent root decomposition "Ellenberg 0877#[ V[ Response to environment "A# GREGARIOUSNESS Mycelis muralis usually occurs as scattered individuals or in small groups "generally two or three plants#[ It does not form patches of appreciable size[ Cover values for M[ muralis in many types of vegetation are low\ often being less than 09) "Zarzycki 0865^ Petrov 0870^ Czarnecka 0875^ Ellenberg 0877^ Rodwell 0880^ Clabby + Osborne 0883#[ In a range of habitats in Britain M[ muralis was most frequently found in ³ 09) of 099!cm1 subsections of a 0!m1 quadrat\ although in woodland it occurred infrequently in up to 39) of 099 cm1 subsections "Grime et al[ 0877#[ In Ireland numbers of plants per 0!m1 quadrat ranged from 0 to 05 in woodland[ Vegetative reproduction does not take place[ "B# PERFORMANCE IN VARIOUS HABITATS Height of ~owering individuals typically ranges from 299 to 599 mm on walls in the open\ or on limestone pavement[ In shaded locations plant height can be up to 0299 mm[ In a woodland site at Durrow\ Co[ Laois\ Ireland\ plant height at maturity averaged 0909 mm 2 79 SD "n 09^ includes ~owering panicle#[ In Ireland plants ~ower and set seed in a variety of habitats including wall tops\ wall faces\ wall bases\ wall embankments\ waste ground\ scrub: woodland\ limestone pavement and grikes in lime! stone pavement[ Non!~owering rosettes are typically less than 399 mm in height "Grime et al[ 0877#[ An examination of seasonal performance of M[ muralis growing on open limestone pavement and in woodland showed that more biomass was produced at the exposed site "Clabby + Osborne 0883#[ Peak biomass of ~owering individuals occurred in July on the open pavement "1[19 g 2 9[50 SE# and in August at the woodland site "9[53 g 2 9[07 SE#[ Similar data were obtained in laboratory experiments "Clabby + Osborne 0886#[ Allocation of plant biomass also varied from habitat to habitat[ Woodland plants typi! cally showed greater root investment than plants from open limestone pavement or grikes "Clabby + Osborne 0883#[ Total ~owering panicle biomass "cap! itula ¦ support structures# accounted for up to 44) of total biomass in plants from open pavement but never more than 19) in woodland plants[ In contrast to the large di}erences in plant biomass and total ~owering panicle biomass between open and shaded sites\ there were much smaller di}erences in the biomass of capitula\ indicating that shading had a relatively small e}ect on reproductive potential "Clabby + Osborne 0883#[ "C# EFFECTS OF FROST\ DROUGHT\ ETC[ Plants do not appear to be vulnerable to frosts in Ireland[ Despite a southerly distribution in Britain 052 G[ Clabby + B[A[ Osborne the continental European distribution of M[ muralis suggests that low winter temperatures do not limit its distribution[ Grime et al[ "0877# suggest that M[ muralis is a drought!avoiding species but there is also evidence for drought resistance[ In a laboratory experiment withholding water until plant pots were reduced to 69) of their initial fully watered weight did not a}ect plant biomass over a 01!week period "Manto 0884#[ Studies in the Burren\ Co[ Clare\ Ireland\ indicate that M[ muralis may be more drought!resistant than some co!occurring species "Osborne + Clabby 0880#[ In open habitats the leaf lobes often curl inwards in periods of dry weather during the summer months[ This may reduce excessive water loss and prevent high!temperature and high! light induced damage[ In open habitats such as wall tops and limestone pavement\ wind can result in damage to the plant when the ~owering panicle has developed[ Plants often respond by producing a second ~owering pan! icle[ woodland site at Babia Gora\ Poland[ There are also several records of vesicularÐarbuscular mycorrhizas occurring on M[ muralis in continental Europe and Britain "Harley + Harley 0876#[ The absence of any mycorrhizal infection has also been reported "Harley + Harley 0876#[ A search of the MYCOLIT database "Trappe + Castellano 0880# revealed no information on mycorrhizal associations of M[ muralis[ "C# PERENNATION] REPRODUCTION Mycelis muralis is a herbaceous perennial hemi! cryptophyte[ The plant is wintergreen\ dying com! pletely back after ~owering in the summer but then producing a small overwintering rosette"s# from a bud"s# on the rootstock[ The plant is generally not monocarpic\ although some literature sources refer to it as a biennial "Cody + Overton 0885# or even annual "Kellman 0863#[ Reproduction is entirely by seed[ "D# CHROMOSOMES VI[ Structure and physiology "A# MORPHOLOGY Leaves have four to _ve variably dissected lobes of unequal size[ The terminal lobes are generally larger\ broadly triangular or hastate "Fig[ 2#[ Lower lobes are hastate or rhombic[ A ~ange connects individual lobes^ ~ange development is greatest in leaves from ~owering plants[ Leaves developed at high light have more indented margins\ with pointed tips and smaller terminal lobes[ The largest lower lobes are found in ~owering plants "Fig[ 2b\d#[ Upper leaves tend to be sessile\ auriculate and less divided\ becoming pro! gressively smaller upwards[ Leaf shapes exist that are intermediate between the examples shown[ The number of stomata on the terminal lobes varies with irradiance[ Upper leaves of plants from a wood! land at Durrow\ Co[ Laois\ Ireland\ had 79[6 2 06[0 SD and 27[7 2 00[1 SD stomata mmÐ1 on their lower "abaxial# and upper "adaxial# surfaces\ respectively\ whereas upper leaves of plants from Mullach Mor\ in the Burren\ Co[ Clare\ Ireland had 097[3 2 03[4 SD and 80[1 2 11[5 SD stomata mmÐ1 on their abaxial and adaxial surfaces "n 2 leaves#[ The leaf surface is smooth\ with the major veins prominent[ The epi! dermal cells are convex\ particularly on the adaxial surface[ Palisade mesophyll tissue is poorly developed and often comprises only one cell layer[ There is little development of sclerenchyma "Osborne et al[ 0883#[ Rooting depth at the Durrow site was 02[64 cm 2 0[60 SD[ Roots comprise two to three major axes with a relatively low density of _ne roots[ Þ 0888 British Ecological Society\ Journal of Ecology\ 76\ 045Ð061 "B# MYCORRHIZA Boullard + Dominik "0859# report an ecto! mycorrhizal infection in M[ muralis collected from a There are numerous European chromosome counts in the literature that give the diploid number 1n 07 "Scrugli 0863^ Dvor²ak 0866^ D|Ovidio 0875^ Grime et al[ 0877#[ In addition\ a report of 1n 07 from near Sheki in Azerbaidzhan has been reported "Love 0868#[ In M[ muralis collected from a forest in the Bites Uplands\ Czech Republic\ the lengths of the pairs of homologous chromosomes ranged from 2[70 to 5[53 mm and the mean chromosome length was 1[42 mm "Dvor²ak 0866#[ Dvor²ak "0866# also reported secondary constrictions in the shorter arms of the _rst pair and on the longer arms of the second pair of homologous chromosomes[ "E# PHYSIOLOGICAL DATA "i# Response to shadin` Although often considered a shade species\ M[ muralis can grow and reproduce across a wide range of irradiances:spectral light qualities both in the _eld and in the laboratory "Osborne + Clabby 0880^ Clabby 0881^ Clabby + Osborne 0883^ Osborne et al[ 0883^ Clabby + Osborne 0886^ G[ Lanigan\ B[ A[ Osborne + G[ Clabby\ unpublished data#[ The reason for its restriction to only a few\ high light and fully exposed habitats in Ireland is not known "Clabby + Osborne 0883#[ Typical responses to irradiance have been observed in both laboratory experiments and _eld studies and include changes in the maximum rate of photosynthesis\ dark respiration rate and light compensation point[ Unlike many species\ there was no evidence of any changes in the bulk light harvesting pigments and relatively small changes in leaf: chloroplast structure and morphology[ At high irradiances the maximum rate and the e.ciency of photosynthesis were depressed "Clabby + Osborne 053 Mycelis muralis "L[# Dumort[ Fig[ 2 Variability in lower leaf shape from mature plants growing in exposed "a\ b# and shaded "c\ d# conditions[ Leaves shown are from vegetative "a\ c# and ~owering "b\ d# plants[ Exposed plants collected from the open limestone pavement of the Burren\ Co[ Clare\ Ireland\ and shaded plants from a woodland in Durrow\ Co[ Laois\ Ireland[ 0880^ Osborne et al[ 0883#[ This indicates that M[ muralis may have a limited capacity to adjust a num! ber of physiological traits to variations in irradiance\ although these features do not exclude it from some high light habitats[ Despite a limited physiological plasticity at the leaf level\ the highest plant and seed productivities are normally found at high "× 49) of ambient# irradiances[ "ii# Response to nutrients Þ 0888 British Ecological Society\ Journal of Ecology\ 76\ 045Ð061 Relatively small responses to nitrate supply were observed[ Plant biomass increased c[ threefold with a 49!fold variation in nitrate supply[ Most of this response also occurred over a relatively small and low "9[14Ð1[9 mol mÐ2# range of nitrate concentrations\ and plants grown at 9[14 mol mÐ2 nitrate achieved biomasses c[ 79) of those found at higher nitrate supplies "Osborne et al[ 0883^ Clabby + Osborne 0886#[ Preliminary experiments also indicate a rela! tively small response to variations in calcium con! centration[ No information is available on the e}ects of other nutrients[ Leaves of plants collected from a woodland site in Britain and a wall site in Ireland contained broadly similar levels of a range of major elements "Table 1#[ Both Ca and K contents were high in comparison with data for a range of other species "Chem[ Anal[^ Hendry + Grime 0882#[ 054 G[ Clabby + B[A[ Osborne Table 1 Chemical characteristics of Mycelis muralis leaves from a wall site in Ireland and a woodland in Britain[ Dried leaves were extracted using concentrated nitric acid and Ca\ Mg\ K\ Na determined using ~ame emission or atomic absorption spectrophotometry as appropriate[ N was determined using the method of Hendershot "0874# and P determined using Murphy + Riley|s "0851# reagent following sulphuric acid digestion using a micro!Kjeldahl procedure "Hendershot 0874#[ Data are expressed as mg gÐ0 with the standard deviation in parentheses "n 2# Location Habitat Grid reference N Durrow\ Co[ Laois\ Ireland Walls S281678 Narborough\ Norfolk\ UK TF649007 11[6 "9[5# 16[2 "9[5# Woodland "iii# Growth and dry matter distribution The highest plant biomasses "0[9Ð1[9 g# and maximum relative growth rates "9[57 mg g−0 week−0# "Osborne + Clabby 0880^ Clabby 0881^ Clabby + Osborne 0886# are low in comparison to many herbaceous plants "Bradshaw et al[ 0853^ Grime + Hunt 0864^ Lambers + Poorter 0881#\ indicating that M[ muralis is a slow!growing species[ Changes in biomass allo! cation in response to variations in irradiance or nitrate supply predominantly involve variations in leaf area ratio "LAR#[ Unlike many studies\ changes in LAR were largely owing to variations in leaf mass ratio\ not speci_c leaf mass "Peace + Grubb 0871^ Corre 0872^ Ackerly + Bazzaz 0884#[ The association of an increased allocation of biomass to plant roots with slow growth may enhance the acquisition of limiting below!ground resources at the expense of light cap! ture and utilization "Tilman 0877^ Poorter + Remkes 0889#[ Alternatively\ a low growth rate could also be a response to environments where there are limiting resources both above! and below!ground "Grime 0868\ 0883#[ "iv# Water relations Leaf water potentials of plants from a variety of habi! tats\ which di}ered in the degree of exposure\ varied from Ð9[3 to Ð9[8 MPa\ with the lowest "more nega! tive# values in material from a fully exposed limestone habitat in the Burren\ Co[ Clare\ Ireland "Osborne + Clabby 0880#[ After an extended dry period at this site the maximum photosynthetic rate was reduced owing to low stomatal conductances[ However\ the magnitude of this e}ect was even greater with the co!occurring species Corylus avellana and Teucrium scorodonia "Osborne + Clabby 0880#[ Generally\ stomatal conductances and transpiration rates are low in M[ muralis and are usually associated with a high water!use e.ciency[ This may be an important characteristic of plants in dry sites\ whether open or shaded[ "F# BIOCHEMICAL DATA Þ 0888 British Ecological Society\ Journal of Ecology\ 76\ 045Ð061 "i# Phenolics The following compounds have been found in the aerial parts of M[ muralis] apigenin!6!glucose\ luteo! P 1[93 "9[92# 0[77 "9[91# Ca Mg 21[53 "2[14# 20[89 "9[54# 3[43 "9[40# 3[23 "9[92# K 21[73 "1[57# 38[23 "0[67# Na 1[74 "9[11# 2[29 "9[13# lin\ luteolin!6!glucose\ quercetin!2!glucose\ ca}eic acid\ chlorogenic acid\ isochlorogenic acid and sco! polin "Man½ez et al[ 0883^ Kisiel + Barszcz 0884#[ A conspicuous feature of plants exposed to high irradiances is an enhanced anthocyanin "a mixture of glycosidic anthocyanidins# pigmentation "Osborne + Clabby 0880^ Osborne et al[ 0883#[ Initially\ antho! cyanin production occurs predominantly on\ or close to\ the lower leaf surface "Wheldale 0805^ Osborne et al[ 0883#[ As the plant matures more anthocyanin is found throughout the leaf\ on stems and on repro! ductive structures[ In the _eld\ anthocyanin pig! mentation is generally associated with plants in exposed situations\ although leaves from woodland understorey plants can have comparable anthocyanin contents during the early spring\ prior to canopy development "G[ Lanigan + B[ A[ Osborne\ unpub! lished data#[ Based on this and investigations which show that anthocyanin production is largely inde! pendent of nutrient supply\ including P concentration "Osborne + Clabby 0880#\ the major environmental factor regulating the production of this pigment is light level "l 399Ð699 nm#[ In the laboratory irradiances as low as 049 mmol mÐ1 s−0 "c[ 09) of full sunlight# can result in signi_cant anthocyanin pro! duction "Osborne et al[ 0883#[ At the same irradiance small increases in anthocyanin were found in response to UV!A "219Ð399 nm# treatments\ although the con! centrations were reduced under UV!B "179Ð219 nm# "G[ Lanigan + B[ A[ Osborne\ unpublished data#[ Although no speci_c information on the cellular location of anthocyanins in M[ muralis is available\ they are usually in the vacuole[ In vivo\ the greatest e}ect of an increase in anthocyanin pigmentation is found in the green\ less strongly absorbed\ wavebands "Osborne et al[ 0883#[ Although often thought to have a photoprotective role\ consistent with an enhanced production at high irradiance\ a vacuolar location would appear to reduce the e}ectiveness of antho! cyanins as photoprotective pigments[ Genetic di}er! ences in populations from an open site "Burren\ Co[ Clare\ Ireland# and a woodland "Durrow\ Co[ Laois\ Ireland# are not related to di}erences in the overall capacity for anthocyanin production by leaf tissue based on mRNA analysis of two key enzymes of the phenylpropanoid pathway\ phenylalanine ammonia 055 Mycelis muralis "L[# Dumort[ lyase "PAL# and chalcone synthase "CHS# "C[ Kavan! agh\ T[ Gallagher + B[ A[ Osborne\ unpublished data#[ There were\ however\ small but signi_cant di}erences in leaf anthocyanin concentration between the two populations\ with higher values for the Burren plants "G[ Lanigan\ B[ A[ Osborne + G[ Clabby\ unpublished data#[ "ii# Terpenoids A number of sesquiterpene lactones have been iso! lated from roots] 7!deoxylactucin\ jacquinelin and its glycoside crepidiaside B\ 8a!hydroxyzaluzanin C\ 8a! hydroxy!00 b\ 02!dihydrozaluzanin and its glycoside ixerin F\ lactuside A\ verno~exuoside "glucozaluzanin C# and its 00 b\ 02!dihydro derivative "Kisiel + Barszcz 0884#[ Minute amounts of crepidiaside B and lactuside A have also been isolated from aerial parts of M[ muralis "Kisiel + Barszcz 0884#[ "iii# Latex production Cut or damaged tissues of all plant parts exude a milky!white\ viscous latex liquid[ Although latex!pro! ducing structures "laticifers of the articulated type# are widespread throughout the Asteraceae "Metcalfe + Chalk 0872#\ there are no speci_c details of the latex!producing structures in M[ muralis[ Latex pro! duction may have a role as an anti!herbivore agent "Harborne 0882#[ "iv# Other compounds Kis + Macalik "0875# found that a mixture of extracts from M[ muralis and Alchemilla vul`aris enhanced epithelization of the skin of white rats that had been subject to experimental burns[ VII[ Phenology Þ 0888 British Ecological Society\ Journal of Ecology\ 76\ 045Ð061 Shoot growth begins early in the season\ although this is likely to depend on local climatic factors[ In Ireland shoot expansion starts in March or April\ although the ~owering spike does not appear until June or July\ depending on whether the plants are in an exposed or shaded location "Clabby + Osborne 0883#[ Mycelis muralis is a long!day plant "Janssen + Lindenmayer 0876# and ~owering commences generally in late June or early July and continues until September or Octo! ber "Grime et al[ 0877^ Clabby + Osborne 0883#[ Seed set and dispersal are from July to September or Octo! ber depending on location "Grime et al[ 0877#[ Flowering is possible after one season providing plants reach an appropriate size[ After ~owering the plant dies back completely\ but in the autumn an overwintering rosette is produced from a bud or buds on the rootstock[ Most seeds germinate in the autumn and overwinter as a small rosette\ although some ger! minate in the following spring[ VIII[ Floral and seed characters "A# FLORAL BIOLOGY Reproduction is amphimictic[ Mej(as "0883# showed that percentage fruit set in capitula bagged before anthesis was almost equal to that of freely pollinated capitula[ This suggests that M[ muralis is largely auto! gamous[ Florets are hermaphrodite and show incom! plete protandry with pollen presentation and stigma exposure taking place within a short time period on the same day "Mej(as 0883#[ Field observations indi! cate that ~orets in a single capitulum are always at the same stage\ typically remaining open for 0 day\ although this is extended if fertilization has not taken place "Mej(as 0883#[ The ~owering panicle is highly branched\ with up to six branching orders "Janssen + Lindenmayer 0876#[ Flowering can take place over a long period "for example more than 1 months under laboratory conditions#\ with roughly equal numbers of capitula open each day "Janssen + Lindenmayer 0876#[ Most capitula occur in the lower half of the ~owering panicle "basi!mesotonic distribution#[ Flowering is basipetal for all branching orders star! ting at the apex of the main axis\ and on the highest _rst order branches "Janssen + Lindenmayer 0876#[ Total numbers of capitula per plant ranged from 87 2 27 SD in a shaded woodland site to 654 2 143 SD "n 4Ð09# in a more open site[ The mean number of pollen grains per capitulum was 3214 "_ve ~orets per capitulum# "Mej(as 0883#[ Pollen grains are 13Ð 25 mm "polar axis# × 15Ð39 mm "equatorial axis# in size "Moreno!Soc(as et al[ 0883#[ An account of pollen development in Lactuca serriola with some reference to M[ muralis is given by Gates + Rees "0810# and further details of pollen morphology are given by Moreno!Soc(as et al[ "0883#[ With its high incidence of self!fertilization M[ muralis may have few insect pollinators[ However\ a beetle "Meli`ethes sp[#\ a muscid "Tachina `rossa "L[## and two species of bee "Halictus sp[\ Panur`us sp[# have been recorded as ~ower visitors "Knuth\ Poll[ 1#[ "B# HYBRIDS There are no records of M[ muralis forming viable hybrids "Hyb[ Br[ Isl[#[ In the USA attempts to cross! pollinate M[ muralis with Lactuca tatarica and L[ canadensis L[ failed[ Lactuca `raminifolia Michx[ ×M[ muralis crosses produced viable seed when L[ `raminifolia Michx[ was the pollen donor\ although plants were abnormal and unable to survive past the seedling stage "Thompson et al[ 0830#[ "C# SEED PRODUCTION AND DISPERSAL Each capitulum bears a maximum of _ve ripe achenes "cypselae# after fertilization\ each with a pappus of hairs that aids dispersal[ The number of seeds per 056 G[ Clabby + B[A[ Osborne plant is di.cult to assess because of the protracted ~owering period[ Assuming that _ve seeds are pro! duced per capitulum\ a plant may produce up to 499 seeds in shaded sites and up to 00 499 in more open sites[ Seeds from a population at Mullach Mor in the Burren\ Co[ Clare\ Ireland had a mean length "includ! ing the beak# of 1[85 mm 2 9[04 SD and a mean width of 9[66 mm 2 9[94 SD "n 09#[ umbia seed bank characteristics of M[ muralis have been studied in clear!cut cedar "Thuja plicata#\ hem! lock "Tsu`a heterophylla# and Douglas _r "Pseudo! tsu`a menziesii# forest "Kellman 0863#[ Six seedlings mÐ1 were obtained in experiments where soil was removed and seeds germinated[ In seed trapping experiments in the _eld up to 096 seedlings mÐ1 were obtained[ These limited data suggest that seeds of M[ muralis persist in the seed bank only for short periods "Thompson et al[ 0885#[ "D# VIABILITY OF SEEDS] GERMINATION Þ 0888 British Ecological Society\ Journal of Ecology\ 76\ 045Ð061 Newly shed achenes germinate readily\ giving rise in nature to seedling populations immediately after the ~owering period[ Seeds may also germinate\ after overwintering\ in the following spring[ In the labora! tory\ dry seeds stored in a refrigerator remained viable for at least 2 years\ but seeds stored at room tem! perature lost viability after 1 years[ Germination typi! cally begins after 05 days and was increased by pre! treatment with a sodium hypochlorite solution "Clabby + Osborne 0886#[ Mej(as "0883# reported that 49) germination occurred within 16 days\ with 89) germination within 21 days[ In contrast\ Grime et al[ "0877# reported 49) germination over the tem! perature range 09Ð13 >C in a 04!day period and in as little as 3 days over the temperature range 04Ð19 >C "J[ G[ Hodgson\ personal communication#[ Cristi + Duran "0873# reported germination rates of 9)\ 09) and 24) at 04 >C\ 19 >C and 24 >C\ respectively\ for seeds from beech woodland near Madrid[ These data suggest the existence of population di}erentiation with regard to germination characteristics[ Grime et al[ "0877# also reported that germination was inhibited by darkness[ Germination rates ranged from 39) to 34) and 01) to 36) in red and green light\ respectively\ whereas only 9Ð3) germinated in far red light and 9Ð8) in blue light "J[ G[ Hodgson\ personal communication#[ In a laboratory experiment leaf!litter leachate from stressed beech trees "Fa`us sylvatica# decreased germination and seedling growth of M[ muralis to a greater extent than leachate from leaves of healthy beech trees "Von Lioba + Schutt 0876#[ Piroznikow "0872# studied seed bank characteristics of M[ muralis in the TilioÐCarpinetum in Poland[ By use of a direct seed!counting method\ the mean number of seeds was 23[5 mÐ1 2 10[04 SD[ In experi! ments where soil was removed to the laboratory and seeds germinated\ the number of seedlings was ³ 0 mÐ1[ Petrov "0866# examined the emergence of M[ muralis seedlings in 0!m1 plots that had been cleared of veg! etation in spruce!pine woodland near Moscow[ A total of four seedlings was recorded\ after a 8!month period\ in two of the 09 0!m1 plots studied[ Only one seedling was obtained in the upper litter layer "0[4Ð 1 cm# from 19 25!cm1 samples taken from similar woodland where soil was removed to the laboratory and seeds germinated "Petrov 0870#[ In British Col! "E# SEEDLING MORPHOLOGY Germination is epigeal^ the _rst true leaf arises in the axis between the two cotyledons after 03 days "Fig[ 3#[ The second true leaf appears after c[ 17 days[ After 31 days the cotyledons are brown and shrivelled[ Roots are characterized by the development of two to three primary axes "Fig[ 3e#[ The leaves are almost reniform "kidney!shaped# with 4Ð5 very shallow lobes\ each of which is subtended by a pointed tip and is somewhat auriculate at the base[ Dependent on the conditions\ the leaves can have a green "low light\ adequate nutri! ents and water# or somewhat reddish "high light\ inad! equate water and nutrients# undersurface\ com! parable to that of the mature plant[ Some narrow ~ange!like leaf development\ with pointed tip!like projections\ can be observed along the petiole[ The petiole is broadly semicircular in cross!section[ The morphology of these juvenile leaves di}ers markedly from those on the mature plant[ IX[ Herbivory and disease "A# ANIMAL FEEDERS AND PARASITES "i# Mammalia Plants appear to be subject to some grazing by cattle in shaded woodland situations\ although not in more open sites[ Some protection may be a}orded by enhanced anthocyanin and latex production when growing in the open[ "ii# Insecta Hemiptera Aleyrodidae] the white~y Aleyrodes proletella "L[# occurs on M[ muralis\ one of its many host plant species "Mound + Halsey 0867#[ Aphididae] Uroleucon muralis "Buckton# occurs only on the upper parts of stems and between the capitula of M[ muralis "Heie 0884#[ Triozidae] Trioza proxima Flor has been recorded from only a single station in Britain "Penshaw Hill\ Durham#\ although it is more widely distributed throughout Europe "Hodkinson + White 0868#[ Coleoptera Curculionidae] the uncommon polyphagous weevil Fig[ 3 Stages in the germination of Mycelis muralis\ c[ 03 "a#\ 10 "b#\ 17 "c#\ 24 "d# and 31 "e# days after sowing[ Germination on moist sand supplemented with one feeding of full strength Long Ashton nutrient solution "Hewitt 0855# at 24 days[ Orthochaetes seti`er "Beck# forms mines on M[ muralis^ adults are normally found at the base of plants "D[ Roy\ personal communication^ Hyman 0881#[ Lepidoptera Pterophoridae] larvae of Pselnophorus hetero! dactyla "Muller# have been recorded in Glou! cestershire "Davis 0812# and in Scotland in the gorge of the River Tilt\ near the old Falls of Fender "v[c[ 78^ Grid Reference NN7655#\ where it was found win! dowing the leaves "Bland 0880#[ Cochylidae] Phalonidia `ilvicomana "Zeller# ova occur on the capitula or stems of M[ muralis and Lapsana communis with the larvae occurring on the achenes\ concealed within the pappus "Emmet 0868#[ Diptera Agromyzidae] Ophiomyia cunctata "Hendel# larvae form white blotch mines along the leaf midrib\ extend! ing irregularly into the leaf blade and pupating at the base of the midrib "Spencer 0861\ 0865#[ Tephritidae] Trypeta immaculata "Macquart# lar! vae form leaf mines but have not been recorded on M[ muralis in Ireland or Britain "Stubbs + Chandler 0867^ White 0877#[ "iii# Other animals There are no records of birds\ Acari\ or nematodes[ "B# PLANT PARASITES Þ 0888 British Ecological Society\ Journal of Ecology\ 76\ 045Ð061 Basidiomycetes Puccinia maculosa "Str[# Rohl has been recorded on M[ muralis but is generally uncommon in Britain "Ellis + Ellis 0874#[ Aecia are found in May\ uredinia from May to June and telia from July "Br[ Rust Fungi#[ Spermogonia have not been seen in Britain but have been recorded in Norway "Br[ Rust Fungi#[ Mayor "0819# showed experimentally that aecia of Puccinia opizii Bubak can form on M[ muralis[ In Britain spermogonia and aecia have been recorded only on Lactuca sativa and L[ virosa^ uredinia and telia on Carex paniculata\ C[ appropinquata and C[ muricata "Br[ Rust Fungi#[ Deuteromycetes Septoria lactucae Pass[ and Septoria prenanthis Eil[ et Ev[ occur on leaves of M[ muralis "Oudemans\ Enum[ 3#[ A Coleosporium "Lev[# sp[ has been recorded by Jo rstad "Br[ Rust Fungi#[ Ascomycetes The cosmopolitan powdery mildew Erysiphe cicho! racearum DC[ has been recorded on M[ muralis "Lebeda 0874^ Braun 0876#\ although Lebeda "0883# details resistance in seven accessions[ Erysiphe poly! `oni DC[ has also been recorded on M[ muralis "Hegi Fl[ ed[ 0\ 0#[ Bremia lactucae Regel occurs on leaves "Oudemans\ Enum[ 3#[ Lebeda + Boukema "0880# studied inter! actions between seven Bremia lactucae Regel isolates from Lactuca serriola and eight accessions of M[ muralis[ Two M[ muralis accessions showed resistance to all iso! lates of B[ lactucae[ Five M[ muralis accessions showed incomplete resistance characterized by limited sporu! lation and one accession showed a range of responses from resistant to susceptible[ Ramularia mul`edii "Bubak# Bubak occurs on leaves "Braun 0887#[ Leptosphaeria quadriseptata J[W[H[ Trail occurs on old stems "Crane + Shearer 0880#[ Leptosphaeria dolioloides "Auersw[# has also been recorded "Hegi Fl[ ed[ 0\ 0#[ 058 G[ Clabby + B[A[ Osborne "C# PLANT DISEASES Extreme resistance or possible immunity to beet west! ern yellows virus "BWYV#\ a disease of many crops including lettuce\ has been reported for M[ muralis "Walkey + Pink 0889#[ In _eld trials to test resistance to BWYV M[ muralis plants showed almost no disease symptoms and no virus was detected in any plant using ELISA serology "Walkey + Pink 0889#[ X[ History Þ 0888 British Ecological Society\ Journal of Ecology\ 76\ 045Ð061 Mycelis muralis is native in Britain "Clapham et al[ 0876#\ although no information is available about its late or postglacial history[ Among the earliest accounts in England is the 06th century record of the herbalist Gerard for Sonchus laevis muralis "a pre! Linnean name for M[ muralis# {upon walls and in wooddy mountainous places| "Druce 0821#[ Other early accounts of the British ~ora indicate its wide! spread occurrence over a large area "Watson 0736\ 0762\ 0772#[ The earliest record of M[ muralis in Ireland is an account by Threlkeld "in Synopsis Stirpium Hib! ernicarum 0615# of Sonchus laevis muralis from the Dublin area "Nelson 0877#[ Most other early Irish records are also from eastern Ireland\ although there were also early occurrences in the south "Clabby + Osborne 0883#[ In Irish topographical botany "Pra! eger 0890# M[ muralis is listed for seven vice!counties[ When the _rst census lists for Irish vice!counties were produced M[ muralis was recorded from 02 vice!coun! ties with additional records from northern\ southern\ western and midland locations "Bot[ Irl[#[ The earliest record for M[ muralis in the Burren\ between Bal! lyvaughan and Black Head\ was sometime between 0823 and 0827 "Praeger 0828#[ Mycelis muralis is now widespread in the Burren[ Outside the Burren there has been a steady if less striking increase in records in eastern\ northern and western areas and M[ muralis has now been recorded from 14 vice!counties[ In Ireland\ outside the Burren region\ the associ! ation of M[ muralis with human activity and its dis! junct distribution suggests that it has been introduced[ The earliest record of M[ muralis in Ireland\ from early 07th century Dublin\ indicates that the plant was boiled to make an infusion which was taken for fevers by poor people "Nelson 0877#[ It may also have been used as a culinary herb "Bot[ Irl[^ Phillips 0866#[ Mycelis muralis is also often associated with the demesnes and estates that became a feature of the Irish landscape\ particularly during the 07th century "Mitchell 0875#[ Planting of non!native species such as beech "Fa`us sylvatica# or lime "Tilia spp[# may have led to the accidental introduction of M[ muralis[ In the Burren\ M[ muralis is not obviously associ! ated with a source of introduction and occurs in a range of semi!natural habitats\ which has given rise to speculation as to its status there "Webb 0851^ Webb + Scannell 0872^ Nelson 0880^ Clabby + Osborne 0883#[ Although it is likely that M[ muralis is not native in the Burren "Clabby + Osborne 0883# its status remains enigmatic and\ in the absence of pre! 0829s records\ may never be satisfactorily resolved[ Acknowledgements We thank Mr Hubert Fuller\ Dr Derek Mitchell\ Dr Rory O Hanlon and Dr James White\ University Col! lege Dublin\ for valuable assistance^ Dr John Hodg! son and sta} of the Comparative Plant Ecology Group\ University of She.eld\ for useful infor! mation^ Dr David Roy\ Institute of Terrestrial Ecol! ogy\ for providing information from the Phyto! phagous Insect Database^ Dr James O Connor\ Natu! ral History Museum\ Dublin\ Dr J[ Parnell\ Trinity College\ Dublin\ the sta} of the National Botanic Gardens\ Dublin\ and the Library sta}\ University College\ Dublin\ for assistance with information retrieval^ Dr Uwe Braun\ Martin!Luther!Universitat\ Halle\ Germany\ and Dr R[A[ Shoemaker\ Agric! ulture Canada Research Branch\ Ottawa\ for myco! logical information^ Mrs Jane M[ Croft\ Environ! mental Information Centre\ ITE\ for producing the British Isles distribution map^ Professor A[J[ Willis and the Associate Editors for helpful comments on earlier drafts of the manuscript[ We also thank Ms Ann Cullen for performing chemical analyses and Mr Hubert Hamilton for ongoing access to Durrow wood[ References Ackerly\ D[D[ + Bazzaz\ F[A[ "0884# Leaf dynamics\ self! shading and carbon!gain in seedlings of a tropical pion! eer tree[ Oecolo`ia\ 090\ 178Ð187[ Bland\ K[P[ "0880# Discovery of the larvae of Pselnophorus heterodactyla "Muller\ 0653# "Lepidoptera] Pter! ophoridae# on a new food plant in Scotland[ Ento! molo`ist|s Gazette\ 31\ 64Ð65[ Boullard\ B[ + Dominik\ T[ "0859# Recherches comparatives entre le mycotrophisme du Fa`etum carpaticum de Babia Gora celui d|autres Fageta precedemment etudies[ Zesz! yty naukowe Wyzszej szkoly rolniczej w Szczecinie\ 2\ 2Ð 19[ Bradshaw\ A[D[\ Chadwick\ M[J[\ Jowett\ D[ + Snaydon\ R[W[ "0853# Experimental investigations into the min! eral nutrition of several grass species[ IV[ Nitrogen level[ Journal of Ecolo`y\ 41\ 554Ð565[ Braun\ U[ "0876# A Mono`raph of the Erysiphales "Powdery Mildews#[ J[ Cramer\ Berlin\ Germany[ Braun\ U[ "0887# A Mono`raph of Cercosporella\ Ramularia and Allied Genera "Phytopatho`enic Hyphomycetes#\ Vol[ 1[ IHW!Verlag\ Eching\ Germany[ Clabby\ G[ "0881# Ecophysiolo`y of Mycelis muralis "L[# Dumort[ in hi`h! and low!li`ht environments[ PhD thesis[ University College Dublin\ Dublin\ Ireland[ Clabby\ G[ + Osborne\ B[A[ "0880# The occurrence of Myce! lis muralis "L[# Dumort[ in woodland in Ireland[ Irish Naturalists| Journal\ 12\ 270Ð272[ Clabby\ G[ + Osborne\ B[A[ "0883# History\ distribution and ecology of Mycelis muralis "L[# Dumort[ "Asteraceae# in Ireland[ Biolo`y and Environment] Proceedin`s of the Royal Irish Academy\ 83B\ 46Ð62[ 069 Mycelis muralis "L[# Dumort[ Þ 0888 British Ecological Society\ Journal of Ecology\ 76\ 045Ð061 Clabby\ G[ + Osborne\ B[A[ "0886# Irradiance and nitrate! dependent variation in growth and biomass allocation of Mycelis muralis[ An analysis of its signi_cance for a functional categorization of {sun| and {shade| plants[ New Phytolo`ist\ 024\ 428Ð436[ Clapham\ A[R[\ Tutin\ T[G[ + Moore\ D[M[ "0876# Flora of the British Isles\ 2rd edn[ Cambridge University Press\ Cambridge\ UK[ Cody\ M[L[ + Overton\ J[McC[ "0885# Short!term evolution of reduced dispersal in island plant populations[ Journal of Ecolo`y\ 73\ 42Ð50[ Corre\ W[J[ "0872# Growth and morphogenesis of sun and shade plants[ I[ The in~uence of light intensity[ Acta Botanica Neerlandica\ 21\ 38Ð51[ Crane\ J[L[ + Shearer\ C[A[ "0880# A nomenclator of Lep! tosphaeria V[ Cesati + G[ de Notaris "Mycota!Asco! mycotina!Loculoascomycetes#[ Illinois Natural History Survey Bulletin\ 23\ 084Ð244[ Cristi\ L[A[ + Duran\ J[M[ "0873# Las semillas de la _to! cenosis {Hayedo de Montejo de la Sierra "Madrid#| y su germinacion en condiciones controladas[ Phyton\ 33\ 06Ð 13[ Czarnecka\ B[ "0875# Ecodiagrams of common species of the forest herb layer in the Roztocze National Park[ Acta Societatis Botanicorum Poloniae\ 44\ 318Ð355[ Davis\ W[B[ "0812# Lactuca muralis\ a food!plant of Psel! nophorus brachydactylus[ Entomolo`ist\ 45\ 126[ Davis\ P[H[ "0864# Flora of Turkey\ Vol[ 4[ University of Edinburgh Press\ Edinburgh\ UK[ D|Ovidio\ R[ "0875# Numeri cromosomici per la ~ora Ita! liana] 0971Ð0982[ Informatore Botanico Italiano\ 07\ 057Ð064[ Druce\ G[C[ "0821# Comital Flora of the British Isles[ Buncle\ Arbroath\ UK[ Dvor²ak\ F[ "0866# Study of chromosomes of angiosperms 4[ Scripta Facultatis Scientiarum Naturalium Universitatis Purkynianae Brunensis Biolo`ia\ 6\ 8Ð29[ Ellenberg\ H[ "0877# Ve`etation Ecolo`y of Central Europe\ 3th edn[ Cambridge University Press\ Cambridge\ UK[ Ellis\ M[B[ + Ellis\ J[P[ "0874# Microfun`i on Land Plants\ An Identi_cation Handbook[ Croom Helm\ London\ UK[ Emmet\ A[M[ "0868# A Field Guide to the Smaller British Lepidoptera[ The British Entomological and Natural History Society\ London\ UK[ Fitter\ A[ "0867# An Atlas of the Wild Flowers of Britain and Northern Europe[ Collins\ London\ UK[ Gates\ R[R[ + Rees\ E[M[ "0810# A cytological study of pollen development in Lactuca[ Annals of Botany\ 24\ 254Ð287[ Gleason\ H[ + Cronquist\ A[ "0852# Manual of Vascular Plants of the Northeastern United States and Adjacent Canada[ Van Nostrand\ Princeton\ New Jersey[ Grime\ J[P[ "0868# Plant Strate`ies and Ve`etation Processes[ Wiley\ Chichester\ UK[ Grime\ J[P[ "0883# The role of plasticity in exploiting environmental heterogeneity[ Exploitation of Environ! mental Hetero`eneity by Plants "eds M[M[ Caldwell + R[W[ Pearcy#\ pp[ 0Ð08[ Academic Press\ London\ UK[ Grime\ J[P[ + Hunt\ R[ "0864# Relative growth!rate] its range and adaptive signi_cance in a local ~ora[ Journal of Ecolo`y\ 52\ 282Ð311[ Grime\ J[P[\ Hodgson\ J[G[ + Hunt\ R[ "0877# Comparative Plant Ecolo`y] A Functional Approach to Common Brit! ish Species[ Unwin Hyman\ London\ UK[ Harborne\ J[B[ "0882# Introduction to Ecolo`ical Biochem! istry\ 3th edn[ Academic Press\ London\ UK[ Harley\ J[L[ + Harley\ E[L[ "0876# A checklist of mycorrhiza in the British Flora[ New Phytolo`ist\ 094 "Supplement#\ 0Ð091[ Heie\ O[E[ "0884# Fauna Entomolo`ica Scandinavica[ Vol[ 20[ The Aphidoidea "Hemiptera# of Fennoscandia and Denmark\ VI[ Brill\ Leiden\ the Netherlands[ Hendershot\ W[H[ "0874# An inexpensive block digester for nitrogen determinations in soil samples[ Com! munications in Soil Science and Plant Analysis\ 05\ 0160Ð 0167[ Hendry\ G[A[F[ + Grime\ J[P[ "0882# Methods in Com! parative Plant Ecolo`y[ Chapman + Hall\ London\ UK[ Hewitt\ E[J[ "0855# Sand and Water Culture Methods Used in the Study of Plant Nutrition\ 1nd edn[ Commonwealth Agricultural Bureau\ Farnham Royal\ UK[ Hodkinson\ I[D[ + White\ I[M[ "0868# Handbooks for the Identi_cation of British Insects[ Vol[ II\ Part 4 "a#[ Homo! ptera] Psylloidea[ Royal Entomological Society\ London\ UK[ Hulten\ E[ "0875# Atlas of North European Vascular Plants\ North of the Tropic of Cancer[ Koeltz Scienti_c Books\ Konigstein[ Hyman\ P[S[ "0881# A Review of the Scarce and Threatened Coleoptera of Great Britain "UK Nature Conservation\ No[ 2#[ UK Joint Nature Conservation Committee\ Peterborough\ UK[ Ivimey!Cook\ R[B[ + Proctor\ M[C[F[ "0855# The plant communities of the Burren\ County Clare[ Proceedin`s of the Royal Irish Academy\ 53B\ 100Ð290[ Jahandiez\ E[ + Maire\ R[ "0823# Catalo`ue des Plantes du Maroc\ Vol[ 2[ Minerva\ Paris\ France[ Janssen\ J[M[ + Lindenmayer\ A[ "0876# Models for the control of branch positions and ~owering sequences of capitula in Mycelis muralis "L[# Dumort[ "Compositae#[ New Phytolo`ist\ 094\ 080Ð119[ Jarol(mek\ I[\ Zaliberova\ M[\ Mucina\ L[ + Mochnacky\ S[ "0886# Ve`etacia Slovenska[ Rastlinne Spoloenstva Slo! venska 1] Synantropna Ve`etacia[ Veda Vydavatelstvo Slovenskej Academie Vied\ Bratislava\ the Slovak Republic[ Kellman\ M[ "0863# Preliminary seed budgets for two plant communities in coastal British Columbia[ Journal of Bio`eo`raphy\ 0\ 012Ð022[ Kis\ Z[ + Macalik\ E[ "0875# Efectul epitelizant al unor extracte vegetale in tratamentul arsurii provocate la sobolani albi "The epithelizing e}ect of some plant extracts in the treatment of burns provoked on white rats#[ Studia Universitatis Babes!Bolyai Biolo`ia\ 20\ 41Ð 43[ Kisiel\ W[ + Barszcz\ B[ "0884# Sesquiterpenes and phenolics from Mycelis muralis[ Polish Journal of Chemistry\ 58\ 0187Ð0299[ Klinka\ K[\ Krajina\ V[J[\ Ceska\ A[ + Scagel\ A[M[ "0878# Indicator Plants of Coastal British Columbia[ University of British Columbia Press\ Vancouver\ Canada[ Klotzli\ F[ "0869# Eichen!\ Edellaub! und Bruchwalder der Britischen Inseln[ Schweizerischen Zeitschrift fur For! stwesen\ 010\ 218Ð255[ Lambers\ H[ + Poorter\ H[ "0881# Inherent variation in growth rate between higher plants] a search for physio! logical causes and ecological consequences[ Advances in Ecolo`ical Research\ 12\ 076Ð150[ Lebeda\ A[ "0874# Auftreten der naturlichen Infektion durch den Echten Mehltau "Erysiphe cichoracearum# bei der Gattung Lactuca in der Tschechoslowakei[ Acta Phy! topatholo`ica Academiae Scientiarum Hun`aricae\ 19\ 038Ð051[ Lebeda\ A[ "0883# Evaluation of wild Lactuca species for resistance of natural infection of powdery mildew "Ery! siphe cichoracearum#[ Genetic Resources and Crop Evol! ution\ 30\ 44Ð46[ Lebeda\ A[ + Boukema\ I[W[ "0880# Further investigations of the speci_city of interactions between wild Lactuca spp[ and Bremia lactucae isolates from Lactuca serriola[ Journal of Phytopatholo`y\ 022\ 46Ð53[ 060 G[ Clabby + B[A[ Osborne Þ 0888 British Ecological Society\ Journal of Ecology\ 76\ 045Ð061 Leitgeb\ E[ "0883# Reaktion der Bodenvegetation auf Dun! gung und Kalkung in einem Fichtenbestand[ Cen! tralblatt fur Das Gesamte Forstwesen\ 000\ 118Ð130[ Love\ A[ "0868# IOPB chromosome number reports LXIV[ Taxon\ 17\ 280Ð397[ Man½ez\ S[\ Recio\ M[C[\ Giner\ R[M[\ Sanz\ M[J[\ Terencio\ M[C[\ Peris\ J[B[\ Stubing\ G[ + Rios\ J[L[ "0883# A chemotaxonomic review of the subtribe Crepidinae based on its phenolic constituents[ Biochemical Sys! tematics and Ecolo`y\ 11\ 186Ð294[ Manto\ M[P[ "0884# Drou`ht Responses of the Wall Lettuce\ Mycelis muralis "L[# Dumort[ "Asteraceae#[ BSc thesis[ Department of Botany\ University College Dublin\ Dublin\ Ireland[ Mayor\ E[ "0819# Etude experimentale du Puccinia opizii Bubak[ Bulletin\ Societe Mycolo`ique de France\ 25\ 86Ð 099[ Mej(as\ J[A[ "0883# Self!fertility and associated ~ower head traits in the Iberian taxa of Lactuca and related genera "Asteraceae] Lactuceae#[ Plant Systematics and Evol! ution\ 080\ 036Ð059[ Metcalfe\ C[R[ + Chalk\ L[ "0872# Anatomy of the Dicoty! ledons\ Vol[ 1\ 1nd edn[ Clarendon Press\ Oxford\ UK[ Mitchell\ F[ "0875# The Shell Guide to Readin` the Irish Landscape[ Country House\ Dublin\ Ireland[ Moreno!Soc(as\ E[\ Mej(as\ J[A[ + D(ez\ M[J[ "0883# Mor! folog(a pol(nica de Lactuceae "Asteraceae# en la pen! (nsula Iberica[ I[ Lactuca L[ y generos relacionados[ Acta Botanica Malacitana\ 08\ 092Ð002[ Mound\ L[A[ + Halsey\ S[H[ "0867# White~y of the World[ British Museum "Natural History# and John Wiley\ Chichester\ UK[ Mucina\ L[\ Grabherr\ G[\ Ellmauer\ T[ + Wallnofer\ S[ Ý sterreichs[ Teil IÐIII[ "0882# Die P~anzen`esellschaften O G[ Fischer\ Stuttgart\ Germany[ Murphy\ J[ + Riley\ J[P[ "0851# A modi_ed single solution method for the determination of phosphate in natural waters[ Analytica Chemica Acta\ 16\ 20Ð25[ Nelson\ E[C[ "0877# The First Irish Flora] Synopsis Stirpium Hibernicarum by Caleb Threlkeld[ Boethius Press\ Kilk! enny\ Ireland[ Nelson\ E[C[ "0880# The Burren] A Companion to the Wild! ~owers of an Irish Limestone Wilderness[ Boethius Press\ Kilkenny\ Ireland[ Oberdorfer\ E[ "0866# Suddeutsche P~anzen`esellschaften[ Teil 0[ G[ Fischer\ Stuttgart\ Germany[ Oberdorfer\ E[ "0867# Suddeutsche P~anzen`esellschaften[ Teil 1[ G[ Fischer\ Stuttgart\ Germany[ Oberdorfer\ E[ "0872# Suddeutsche P~anzen`esellschaften[ Teil 2[ G[ Fischer\ Stuttgart\ Germany[ Osborne\ B[A[ + Clabby\ G[ "0880# Ecophysiology of Myce! lis muralis "L[# Dumort[ in the Burren\ Co[ Clare\ Ireland[ Botanical Journal of Scotland\ 35\ 16Ð35[ Osborne\ B[A[\ Clabby\ G[\ Horsley\ D[ + Nolan\ P[F[ "0883# Is acclimation required for success in high light environ! ments< A case study using Mycelis muralis "L[# Dumort[ "Asteraceae#[ New Phytolo`ist\ 016\ 252Ð264[ Peace\ W[J[H[ + Grubb\ P[J[ "0871# Interaction of light and mineral nutrient supply in the growth of Impatiens parvi~ora[ New Phytolo`ist\ 89\ 016Ð049[ Petrov\ V[V[ "0866# Reserve of viable plant seeds in the uppermost soil layer beneath the canopies of coniferous and small!leaved forests[ Moscow University Biolo`ical Science Bulletin\ 21\ 22Ð39[ Petrov\ V[V[ "0870# Content of viable dormant seeds in the soil of certain types of conifer forests[ Moscow University Biolo`ical Science Bulletin\ 25\ 2Ð7[ Phillips\ R[ "0866# Wild Flowers of Britain[ Pan Books\ London\ UK[ Piroznikow\ E[ "0872# Seed bank in the soil of stabilized ecosystem of a deciduous forest "TilioÐCarpinetum# in the Bialowieza National Park[ Ekolo`ia Polska\ 20\ 034Ð 061[ Poorter\ H[ + Remkes\ C[ "0889# Leaf area ratio and net assimilation rate of 13 wild species di}ering in relative growth rate[ Oecolo`ia\ 72\ 442Ð448[ Praeger\ R[L[ "0890# Irish topographical botany[ Pro! ceedin`s of the Royal Irish Academy\ 6B\ 0Ð309[ Praeger\ R[L[ "0828# A further contribution to the ~ora of Ireland[ Proceedin`s of the Royal Irish Academy\ 34B\ 120Ð143[ Preston\ C[D[ + Hill\ M[O[ "0886# The geographical relation! ships of British and Irish vascular plants[ Botanical Jour! nal of the Linnean Society\ 013\ 0Ð019[ Quezel\ P[ + Santa\ S[ "0852# Nouvelle Flore de l|Al`erie\ Vol[ 1[ Centre National de la Recherche Scienti_que\ Paris\ France[ Rode\ M[M[ + Runge\ M[ "0880# Combined e}ects of alu! minium and nitrogen forms on root growth of ten eco! logically distinct plant species[ Plant Roots and their Environment "eds B[L[ McMichael + H[ Persson#\ pp[ 152Ð161[ Elsevier\ Amsterdam\ the Netherlands[ Rodwell\ J[S[ "0880# British Plant Communities[ Vol[ 0[ Woodland and Scrub[ Cambridge University Press\ Cam! bridge\ UK[ Scrugli\ A[ "0863# Numeri cromosomici per la ~ora Italiana] 056Ð060[ Informatore Botanico Italiano\ 5\ 26Ð43[ Segal\ S[ "0858# Ecolo`ical Notes on Wall Ve`etation[ Junk\ The Hague\ the Netherlands[ Silvertown\ J[W[ "0871# Measuring plant distribution in limestone pavement[ Field Studies\ 4\ 540Ð551[ Silvertown\ J[W[ "0872# The distribution of plants in lime! stone pavement] tests of species interaction and niche separation against null hypotheses[ Journal of Ecolo`y\ 60\ 708Ð717[ Soldatenkova\ Y[P[ "0871# The ~uctuations of cen! opopulations of certain plant species in the grassÐshrub cover in parcels of PiceetumÐHylocomiosum[ Vestnik Moskovsko`o Universiteta Biolo`iya\ 26\ 07Ð13[ Spencer\ K[A[ "0861# Handbooks for the Identi_cation of British Insects[ Vol[ X\ Part 4 "`#[ Diptera] A`romyzidae[ Royal Entomological Society\ London\ UK[ Spencer\ K[A[ "0865# Fauna Entomolo`ica Scandinavica[ Vol[ 4[ The A`romyzidae "Diptera# of Fennoscandia and Denmark[ Scandinavian Science Press\ Klambenborg\ Denmark[ Stace\ C[ "0886# New Flora of the British Isles\ 1nd edn[ Cambridge University Press\ Cambridge\ UK[ Stubbs\ A[ + Chandler\ P[ "0867# A Dipterist|s Handbook[ The Amateur Entomologists| Society\ London\ UK[ Thompson\ K[\ Bakker\ J[ + Bekker\ R[ "0885# The Soil Seed Banks of North West Europe] Methodolo`y\ Density and Lon`evity[ Cambridge University Press\ Cambridge\ UK[ Thompson\ R[C[\ Whitaker\ T[W[ + Kosar\ W[F[ "0830# Interspeci_c genetic relationships in Lactuca[ Journal of A`ricultural Research\ 52\ 80Ð096[ Tilman\ D[ "0877# Plant Strate`ies and the Structure and Dynamics of Plant Communities[ Princeton University Press\ New York\ NY[ Trappe\ J[M[ + Castellano\ M[A[ "0880# MYCOLIT] A Mycorrhiza Biblio`raphy\ 0647Ð0880[ Mycologue Pub! lications\ Waterloo\ UK[ Von Lioba\ P[ + Schutt\ P[ "0876# Auswaschung phy! totoxischer Substanzen aus Blattern kranker und gesun! der Buchen Ð Schaden an der Boden~ora[ European Journal of Forest Patholo`y\ 06\ 245Ð251[ Walkey\ D[G[A[ + Pink\ D[A[C[ "0889# Studies on resistance to beet western yellows virus in lettuce "Lactuca sativa# and the occurrence of _eld sources of the virus[ Plant Patholo`y\ 28\ 030Ð044[ 061 Mycelis muralis "L[# Dumort[ Þ 0888 British Ecological Society\ Journal of Ecology\ 76\ 045Ð061 Wallen\ C[C[ "0869# Climates of Northern and Western Europe[ Elsevier\ Amsterdam\ the Netherlands[ Watson\ H[C[ "0736# Cybele Britannica[ Longman\ London\ UK[ Watson\ H[C[ "0762# Topo`raphical Botany[ Thames Ditton\ London\ UK[ Watson\ H[C[ "0772# Topo`raphical Botany\ 1nd edn[ Quar! itch\ London\ UK[ Webb\ C[J[\ Sykes\ W[R[ + Garnock!Jones\ P[J[ "0877# Flora of New Zealand\ Vol[ 3[ Botany Division\ Department of Scienti_c and Industrial Research\ Christchurch\ New Zealand[ Webb\ D[A[ "0851# Noteworthy plants of the Burren] a cata! logue raisonne[ Proceedin`s of the Royal Irish Academy\ 51B\ 006Ð023[ Webb\ D[A[ + Scannell\ M[J[P[ "0872# Flora of Connemara and the Burren[ Royal Dublin Society\ Dublin\ Ireland[ Wheldale\ M[ "0805# The Anthocyanin Pi`ments of Plants[ Cambridge University Press\ Cambridge\ UK[ White\ I[M[ "0877# Handbooks for the Identi_cation of British Insects[ Vol[ X\ Part 4 "a#[ Tephritid Flies\ Diptera] Tephritidae[ Royal Entomological Society\ London\ UK[ White\ J[ + Doyle\ G[ "0871# The vegetation of Ireland] a catalogue raisonne[ Journal of Life Sciences\ Royal Dub! lin Society\ 2\ 178Ð257[ Zarzycki\ K[ "0865# Ecodiagrams of common vascular plants in the Pieniny Mountains "the Polish West Carpathians#[ I[ Ecodiagrams of selected woodland species[ Fra`menta Floristica et Geobotanica\ 11\ 368Ð386[

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