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Cuscuta Epithymum (L.) L. (Convolvulaceae), Its Hosts And

Cuscuta Epithymum (L.) L. (Convolvulaceae), Its Hosts And

Cuscuta epithymum (L.) L. (), Its Hosts and Associated Vegetation in a Limestone Pavement in Lowlands in County Clare (H9), Western Author(s): G. J. Doyle Source: Biology and Environment: Proceedings of the Royal Irish Academy, Vol. 93B, No. 2 (Jun., 1993), pp. 61-67 Published by: Royal Irish Academy Stable URL: http://www.jstor.org/stable/20499879 . Accessed: 08/08/2013 20:25

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This content downloaded from 140.203.12.206 on Thu, 8 Aug 2013 20:25:17 PM All use subject to JSTOR Terms and Conditions EPITHYMUM (L.) L. (CONVOLVULACEAE), ITS HOSTS AND ASSOCIATED VEGETATION IN A LIMESTONE PAVEMENT HABITAT IN THE BURREN LOWLANDS IN COUNTY CLARE (H9), WESTERN IRELAND

G. J. Doyle

ABSTRACT

Cuscuta epithymum (L.) L. (common dodder) has been found growing in a limestone pavement habitat in the Burren Lowlands (H9) in County Clare, westem Ireland. The species is relatively rare in Ireland and is confined to sixteen coastal vice-counties. On limestone pavement Cuscuta is found in vegetation belonging to the Asperulo-Seslenietum, an association assigned to the chalk grassland class Festuco-Brometea. The vegetation of the limestone pavement habitat is compared with mature dune grassland at Fanore, also in the Burren region, where extensive populations of Cuscuta occur in vegetation assigned to the Camptothecio-Asperuletum, another association belonging to the same class.While there are species differences between the communities in these contrasting , there is considerable flonistic overlap. Cuscuta epithymum is catholic in its selection of host at these sites. The hosts common to the two sites include Achillea millefolium, Lotus corniculatus,, Asperula cynanchica, Tnfolium pratense and Viola species. There are fourteen additional hosts on the limestone pavement, and fifteen confined to the mature dune grassland site. Despite the catholicity of host selection, the ranrtyof Cuscuta in Ireland suggests that establishment is a critical determinant of the species' distribution, and depends on the initial infection of a primary host in an appropriate habitat with suitable environmental conditions.

G. J.Doyle, Department of INTRODUCTION associated with acid. 'grass-heathlands' of the Botany, University College Nardo-Galion Prsg. 1949, and dry calcareous Dublin,Belfield, Dublin 4, Parasitic Cusctita epithymum (L.) L. (common grasslands of the Festuco-Brometea Br.-Bl. et Tx. Ireland. dodder) is, in Ireland, confined to coastal regions: 1943 (Rothmaler 1976). the is now recorded in sixteen vice-counties Webb (1977) considers C. epithymum a very (Scannell and Synnott 1987). The species was rare plant in Ireland and states that it is distributed previously located inMeath (H22) but there are no on sandy ground near the sea and mainly in the modem records for the plant in that vice-county. southern half of the island. While Scannell and Cuscuta epithymum is widely distributed on the Synnott (1987) consider the species a native of European mainland and in the south-east part of sand-dunes in Ireland, Webb and Scannell (1983) Britain (Fig. 1), but is absent from much of the west and Nelson (1991) suggest that there is no place in and north of Bnrtain and is confined to the southern Ireland where this plant is undoubtedly native. parts of Fennoscandia (Perring and Walters 1976; A relatively well-documented site for C. Meusel et al. 1978; Hulten and Fries 1986). epithymum is at Fanore in the Burren, the karstic In north-west , C. epithymum ismainly region of north-west County Clare on the Inrsh associated with heathland vegetation belonging to west coast (Fig. 2). Cuscuta was first found in that the Calluno-Ulicetea Br.-Bl. et Tx. 1943, par area by Druce (1909) 'in pasture about a mile ticularlv the gorse heaths of the Ulicetalia minonrs [1.6km] south of Black Head'. Specimens lodged in (Duvign. 1944) Gthu 1973 (Ttixen 1970; the at the National Botanic Gardens at Received18 February Gimingham 1972; Westhoff and Den Held 1975; Glasnevin, Dublin, by A. W. Stelfox in 1924 were found near the Caher River at 'Murrough' Read13 May1993. Oberdorfer 1979; Rieley and Page 1990; Rodwell (Murroogh), about 3.4km south of Black Head. Published28 June1993. 1991). On mainland Europe C. epit/symiuin is also

BIOLOGY .AN)ENDVlIRONME-NTPR(CE)INS; OF THE Roy-A IRiSHAC\DLE\Y. VOL. 93B. No.. 61-67 (1993). C ROYAL IRISHACADEMY 61

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Further specimens were collected from Fanore dunes by Dr P. O'Connor in 1934. Some years later,Webb (1947) recorded the plant at Fanore 'on the edge of the sand-dunes that lie immediately to the north of the mouth of the Caher river, 2.5 miles [4kml south of Black Head'. Later Webb (1962) noted that the plant grew in 'great profusion' at Fanore and had obviously extended its range since he first saw it there in 1947. Webb and Scannell (1983) list the plant as 'very abundant on the dunes at Fanore'. Reconnaissance of Fanore in 1990 showed that the plant is abundant over much of the mature dune system, from Murroogh in the north to the recreation area near the old schoolhouse in the south. Survey of pastures between Fanore and Black Head failed to relocate the plant in that area. Until now, C. epithymum has not been recorded in any other mainland Burren station, but was found in 1890 on the (Nowers and Wells 1892), where it is frequent on dunes at Portmurvy and Killeany on Inishmore, and north of the landing-stage on Inishmaan (Webb and Scannell 1983). The Fanore and Aran sites for Cuscuta are located in the Burren Hills (District 2), the western section of the Burren as defined by Webb and Scannell (1983). Ivimey-Cook and Proctor (1966) found that at Fanore C. epithymum occurred in mature dune grasslands, which they assigned to two classes, the 50cm of bare limestone between adjacent host Fig.1- European Koelerio-Corynephoretea Klika in Klika et Novak plants. The area is grazcd by cattlc and a part has distributionof Cuscuta 1941 and the Festuco-Brometea Br.-Bl. Tx. 1943 et been used as a foddering area in winter. epithymum.The Irish em. Tx. 1961. distribution is based on The vegetation inwhich Cusctita grows is typi- thevce-couty There are no detailed descriptions of C. cal of many pavement areas in the eastern part of the distributionlisted in epithymum in heathland vegetation in Ireland, but Burren (Table 1). This vegetation is classified as: Scannelland Synnott materials in the herbarium at the National Botanic Asperulo-Seslerietum (Br.-Bl. et Tx. 1952) 1987. TheBritish Gardens, Dublin, indicate that Cuscuta has been Shimwell 1971 distributionis basedon found on gallii in heathland. Perringand Walters In this paper, nomenclature for higher plants Seslerio-Mesobromenion Oberd. 1957 1976. TheEuropean and nmosses follows Tutin et al. 1964-80 and Smith Mcsobromion (Br.-Bl. et Moor 1938 em. mainlanddistrbution is 1978. Syntaxonomy follows the scheme for Irish Oberd. 1949) Oberd. 1957 basedon theworks of Meusel et al. (1978) inWhite 1982. vegetation presented and Doyle Brometalia (Koch 1926 n.n.) Br.-Bl1. 1936 andHulten and Fries Festuco-Brometea Br.-Bl. et Tx. 1943 cm. Tx. (1986). A NEW LIMESTONE PAVEMENT HABITAT 1961 FOR CUSCUTA IN THE BURREN Vegetation of dry chalk grasslands in Europe is LOWLANDS referred to the Festuco-Brometea. The diagnostic species for the Asperulo-Seslerieturn, as listed by On 15June 1990 Cuscuta epithymum was found White and Doyle (1982), that arc present in the growing among vegetation on limestone pavement vegetation at Cooloorta include Sesleria albicans, south of Cooloorta (Irish grid reference R3496) in Geranium sanguineuim, Carlina vulgaris, Asperula the lowland area to the east of Mullagh More (Fig. cynanchica, Hieracium pilosella, Blackstonia perfoliata, 2), referred to as the Burren Lowlands (District 3) Sanguisorba minor, Filipendula vulgaris and Dryas inWebb and Scannell 1983. The station lies about octopetala. 30m above sea-level and some 17km from the sea The vegetation is grass-dominated, low at its nearest point, to the north at Kinvarra, Co. growing (40cm) and confined to organic-rich soil Galway. This constitutes a new record for the about 10cm deep, among limestone pavements. In species in this part of the Burren. some places, exposed pavement is extensive and At Cooloorta, C. epithymum extends over an vegetation provides sparse cover. In quadrat 1, total area of 50m x 5Gm. In places Cuscuta stems span vegetation cover is 40)%, cover 20%,

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Table 1 Releves of limestone pavement vegetation containing Cuscuta epithymum found at Cooloorta in Galwa~? the Burren Lowlands. Cover/ XBren Galway abundance values according to the Braun-Blanquet scale are used (cf. Clarinbridge Muelier-Dombois and Ellenberg ______. Bav __ _ _ _ a GalwYay 1974). The quadrat size is Orm x 1Om. Total vegetation cover Black Aran Islands Head | is 40% in releve 1 and 80% in releve 2. lilshmor;Inishmo>re ~~~~~~FanoreBallyvaughan / v.Knvaram Relevenumber 1 2

A >,=_i Lisdo onararna 'tCooloorta i Asperulo-Seslerietum character species Dryas octopetala 2 1 Kilfenora. I 4 Mullagh More N J 2 Killinaboy4\Connell's Ford Geranium sanguineum 1 1 Corofint Seslenro-Mesobromenion character %.s species Sesleriaalbicans 2 3 0 5 10 km " Ennis Festuco-Brometea character and differential species Carlina vulgaris + + Fig.2-Location maps of cover 30%, and cover 30%. In other Asperula cynanchica + + theBurren region in places, vegetation cover is greater. In quadrat 2, Hieracium pilosella + + Ireland,and the locations total cover is 80%, with contributing 10%, Blackstonia perfoliata + of sites at lnishmore(Aran 60% and 30%. The cover of Cuscuta Sanguisorba minor + Islands),Fanore, is less than 3% in each of the quadrats. Filipendula vulgaris + Cooloorta and Connell's Ford(all three on the The grassy swvard is predominantly Sesleria Companion species Burrenmainland) that albicans, wvithBriza ?tnedia,Festuca nrbra, Carexflacca Ctiscuita epithymum 1 1 supportCuscuta and Anthoxanuthutn odorattint also present but with Rosa 2 1 epithymum(marked with low cover. As is typical for this Burren grassland, pimpinellifolia Prntuts spinosa 2 1 starsymbols). The Burren there are several shrub species present that typically regionincludes the karstic grow in a stunted or prostrate fashion: the more T7hymuspraecox 1 1 Calluna vulgaris + + limestonearea of north- common of these include Rosa piypinellifolia, Dryas west Clareand the Aran and both Teucrium scorodonia 1 1 oct'opetala PnutXs spinosa, while Callunva Islands,which lieoff the Lotus corniculatus 1 1 tMgaris and Thyinus praecox are present but have lowv west coast of Ireland.The - - Poteitilla erecta + + of cover. Herbaceous of this limtcoastlimits of thethelmsTone limestone dicotyledons typical Minuartia vertia + + region,as definedby V-egetation include Geranium satqittnewnt, Teicriint Suiccisapratensis + 1 Webband Scannell scorodonia, Ltfi-s coricumlatus, Potetitilla erecta, Euiphrasia sp. + + are indicated 'ena, and Hieraciim (1983), by .Minuartia Aspenvla c)nanchica Briza mtedia 1 1 means of a singlebroken pilosella. Of the sev-eral mosses present Breutelia + 1 line. The Burren has been chrysvotria is predomiinant. Carexflacca 1 1 dividedby Webb and In September 1990. was found in Cisctuta Pteridiuim aquilinum + 1 Scannellinto the Burren on Callhta Thyntus flowver vtlgaris, Dryas octopetala, 2 Hills (District 2) to the Rosa Achillea Breutelia chrysocoma 1 praecox-, pimzpitellitolia, Pndnts spiniosa, and the Burren I Tortella tortuiosa + + west, .ariipaii rtundofia, Geraniun F . Sfllletux~FllJm ilipantl tfllol eaz Dicralnmt scoparium + + Lowlands (District 3) to -l ' S Pten a ' S .lnein, .a theeast. Thetwo districts sansy,ii1'eum,Lnus ornilai Poteni ila ereaa, Susa areseparaied by the61m prateizsis, Tesint7in scor. doniia and Trifloii1n pratetnse Species confined to a single quadrat: releve 1- (200ft)contour that skirts (specimens are lodged in the herbanrum of the Centtaurea tiigra+, Crataegus monogyna 1, Daucus carota thehill of Mullagh More, National Botanic Gardens. Dublin). In June 1991, +, Mycelis muralis +, Plantago maritima +, Polygala which is indicatedby a the plant wvas again found in vigorous condition, vulgaris +, Senecio jacobaea +, Solidago virgaurea +, triangle.District 2/3 extending over roughly the same area as the Taraxacumn officitnale +, Asplenium ruta-muraria +, boundaryis indicatedby a previous and in September 1991 again ycar. wvas Ctenidium inolluscmn 1, Homalothecium sericeum +, doubledbroken line found producing abundant flowvers. .\eckera crispa 1, Pleurozium schreberi+; releve 2 running roughly in a Atntentaria dioica +, Anthoxanthum odoratum +, nort-sothnorth-south drecionSubsequently,direction Guscuta was fiound In ano)ther throughthe region. Burren Lowlands site in November 1991 by Dr Trifolium pratense +, Homalothecium lutescens 1, Noel Kirby. The plant occurred in grassland Hylocomium splendens +.

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vegetation on a slope of an old excavation in glacial Table 2 Sand-dune vegetation in which Cuscuta epithymum is drift to the west of the roadway between Killinaboy found at Fanore, Co. Clare (columns 1-4 and column 6), and Mullagh More near the bridge at Connell's and at Mullaghmore, Co. Sligo (column 5). Ford (R2993), about 5km south-west of the Cover/abundance values according to the Braun Cooloorta site and at about 30m above sea-level. At Blanquet scale are used for releves 1-5. Roman numerals that time Cuscuta was still in and grew on in column 6 are presence class values based on nine Thymus praecox and Lotus corniculatus. releves taken from Ivimey-Cook and Proctor 1966: V = presence in 81-100% of the releves, IV = 61-80%, III = COMPARISON OF THE LIMESTONE 41-60%, II = 21-40% and I = 1-20%; the associated PAVEMENT AND MATURE DUNE superscripts indicate the range of Braun-Blanquet values HABITATS OF CUSCUTA IN THE for each species in the releve set. Quadrat size for releves BURREN REGION 1-5 was 5m x 5m.

The limestone pavement habitat and vegeta Releves tion described from Cooloorta are markedly 1 2 3 4 5 6 different to those at Fanore dunes and other Irish dune systems where Cuscuta has been recorded. Slope 10 250 00 00 50 0-30o Vegetation descriptions from sand-dune habitats at Cover (%) 80 100 60 100 100 - Fanore, Co. Clare (MI 308), and Mullaghmore, Co. Sligo (G7157), made by the author in 1991, together with a summary of the descriptions from Camptothecio-Asperuletum Fanore listed in Ivimey-Cook and Proctor 1966, character species are presented in Table 2. Asperula cynanchica + I 1 V+-2 The vegetation inwhich Cuscuta occurs in these areas is typical of stable landward dunes in the west Festuco-Brometea character of Ireland, and is classified as: and differential species Camptothecio-Asperuletum Br.-Bl. et Tx. Ranunculus bulbosus 1 + 1 + . P 1952 Homalothecium lutescens 2 + 1 V+-3 Eu-Mesobromenion Oberd. 1957 Koeleria macrantha. + + + 111-2 Mesobromion (Br.-Bl. et Moor 1938 em. Hieracium pilosella 2 1 . III+ Oberd. 1949) Oberd. 1957 Blackstonia perfoliata + + III+-1 Brometalia (Koch 1926 n.n.) Br.-Bl. 1936 Gentianella amarella 1 I+ Festuco-Brometea Br.-Bl. et Tx. 1943 em. Tx. Pleurochaete squarrosa 1111-2 1961 Arenaria serpyllifolia . 1+ The character species of the Camptothecio Carlina vulgaris 1+ Asperuletum is Asperuila cynaichlica. Character and differential species of the alliance, order and class include Koeleria macrantlia, Hieraciuim pilosella, Companion species V+-3 Ranunculus bulbosus, Blackstonia perfoliata, Gentianiella Cuscuta epithymum 2 2 1 2 1 amarella, Arenaria serpyllffolia, Carlina vulgaris, Festuca rubra 3 4 2 5 3 Vl-4 Homalothecium (Camptothecium) lutescens and Pleuro 3 3 2 1 IV+ chaete squarrosa. The assignment by Ivimey-Cook Hypochoeris radicata 1 1 1 1 IV+-' and Proctor (1966) of several of their releves to the Trffolium pratense 2 1 . 1 2 Koelerio-Corynephoretea does not appear to be Galium verum 2 2 1 2 IVI-2 as have the of the justified, all diagnostic species Plantago lanceolata 1 1 1 + III+1 Festuco-Brometea. Lotus corniculatus 1 2 . 2 2 V+-2 On the majority of the stable sand-dunes Tortula ruralformis 2 2 1 1111-2 examined, the vegetation cover is complete and Thymus praecox 1 1 2 2 V3-4 grass-dominated, with Festuca rubra forming the Agrostis stolonifera + + + V+-2 sward in most places. Scattered tussocks of Anagallis arvensis + 1 . . IV+ Ammophila arenaria are a feature in some areas. 1 1 + Other notable higher plants include Hypochoeris + radicata, Trifolium pratense, Galium verum, Plantago Carex arenaria I 1 1+ lanceolata, Lotuis corniculatus and Thymus praecox. The 1 + . IV+1 prominent is Tortula ruiralf/ormis. Rhytidiadelphus squarrosus + . 1 1 III At Fanore, C. epithymum forms extensive mats, Pseudoscleropodium purum + . IIt with cover of up to 50% in places, so that the plant Holcus lanatus + + is visible from a distance. It is found on level ground Cynosurus cristatus . + .

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Table 2 continued and on the flanks of dunes on slopes of up to 250. Evidence of heavy grazing by rabbits and domestic . 1 . 1Vl-2 Medicago lupulina animals is apparent in most places. The northern sp. . + . 1 + part of Fanore atMurroogh and the stable dunes at Ditrichumflexicaule . 2 . . IV+-3 Mullaghmore in County Sligo are major rabbit + + + + V1-2 warrens. Poa pratensis 1 . While there aremarked differences between the Cerastiumfontanum . . + . IV+ sand-dune vegetation at Fanore and the limestone Carexflacca . . + . 111-2 pavement vegetation described from Cooloorta, there Linum catharticum . . - + 1 IV' are species common to the two habitats. These include Luzula campestris . . . 1 + IV+1 Asperula cynanchica, Blackstonia peyfoliata, Carlina Leontodon taraxacoides . . 2 IV1-2 vulgaris, Euphrasia species, Hieracium pilosella, Lotus Prunella vulgaris . . . + IIP corniculatus, Polygala vulgaris, Senecio jacobaea, pratense, Centaurium erythraea . . . + III+1 Taraxacum officinale, Thymus praecox, Tafolium Briza media, Carex flacca, Festuca rubra, Ctenidium Peltigera canina . . . + Ivi molluscum, Homalothecium lutescens, Hylocomium splendens and Pleurozium schreberi. Additional species: releve 1- Lapsana communis+; releve 2- Bniza media 1,Ctenidium molluscum 1; releve 4- Poa annua +; releve 5 Carex panicea FOR IN I, Climacium dendroides 1, Hylocomium splendens2, Pleurozium schreberi1, Sagina HOST PLANTS CUSCUTA ITS wodosa+, Senecio jacobaea +, Thuidium tamariscinum2, Veronica chamaedrys+; BURREN HABITATS colunm 6 - Campanula rotundffolia 111,Desmezeria rigida II+-I, Cerastium hifusum 1+-1, Euphrasia salisburgensis 11%Festuca ovina II1-3, Plantago coronopus Several authors have identified host plants for [II, Polygala vulgaris II+, Tnfolium repens IV'-2, Viola riviniana IV+-', Entodon Cuscuta in Ireland. More (1892) listed Thymus xncinnus III 1-2,Hypnum cupressjformnevar. lacuinosumIV+-2, Lophocolea bidentata praecox, Lotus corniculatus, Trffolium repens and 11+-1( confined to just one or two releves in Ivimey-Cook and Galium verum as hosts of Cuscuta on dunes at Proctor's data have been omltted for brevity). Tramore, Co. Waterford. Webb (1962) listed Thymus praecox, Lotus corniculatus and Euphrasia species as hosts at Fanore dunes, while Webb and Scannell (1983) identified Thymus praecox and Lotus Table 3- Host species for Cuscuta epithymum at Cooloorta and corniculatus as the major hosts at Fanore, and Galium Fanore in County Clare and on plant specimens at the verum and Asperula cynanchica as minor hosts there. herbarium, National Botanic Gardens, Dublin. While these statements appear to restnrct the number of hosts, the parasite is known to have a Major host species, found at Cooloorta, at Fanore and on wide variety of host species in Britain (Stace 1991) herbarium materials and continental Europe (cf. Frolisek 1981). .4chilleamillefolium, LotIus corticulfatuis,Tziymus praecox. In examining the vegetation containing Cuscuta at Fanore and Cooloorta in the Burren, it Hosts common to Cooloorta and Fanore became apparent that the parasite was also dis Asperula cynanichfica,Tnfioliun pratense, Viola species. trbuted on awide vanrety of species, so a systematic Hosts at one field site (C = Cooloorta; F = Fanore) and in survey of Cuscuta hosts was undertaken at these herbarium material Clare sites (Table 3). Hosts identified in the field Festuca nebra (C), Potentilla erecta (C). Galium :'enuz (F). were those to which Cuscuta was attached by suckers that left distinct holes in the plant on Hosts confined to Cooloorta removal. A list of host species in preserved plant Antennaria dioica, Blackstonia Calluaza Aspleninum nuat-murana, perfioliata, materials at the herbanrum of the National Botanic vulgaris, oct(petala, Ca:npatlula Geratium sangitneiu:::, DLyas rotundfiolia, Gardens, Dublin, is also included. Minuartia 'eta, Pnmttusspinosa, Rosa piJpinielliflia, Succ&sapratensis, Teucrium A total of 48 host species for Cuscuta were scorodotia identified. The major hosts are Achillea millefolium, Hosts confined to Fanore Lotuis cornictulartusand Thymus praecox, species that Bellis peretnniis, Briza media. Cerasium fitaamm. Euphrasia salisburgensis, were located at both of the field sites and found on Hieracium pilosella, Hypclwnis radicara,Koeleria tacranth/a, LuZula canmpestris, several herbarium specimens. Three hosts, Asperula Plantago lanteol?ata,Polveala rlgaris, Ranuuadlus bulbosus.,Rhinanduls minor, cyniancdica,Trifolium pratense and Viola species, were Rhytidiadelphus- squarrosus. Taraxiacmljticina2le. found at the two Burren stations investigated, while Festuica ntbra, Galiumralvernm and Potentilla erectawere Hosts on herbarium material hosts at one or other of the Burren sites and found Anthyllis ulnneranua.&n:aurea mr Daucs carota, Enica mackaiana (planted). on herbanrum material. Of the other 26 host species Erica teeralix (planted). man'tinuems. praeteuis, Leucanthentium EryvZeiwin La;:hynL5 located in the field, 12 were confined to the vulgare, .lledicago lupiln?a, Onfonis apens, Senecio jaobaea, Trifolium71species. limestone pavement habitat at Cooloorta and 14 to Ulex gallii

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the sand-dunes at Fanore. An additional 13 hosts plants, a perennating mechanism described for C. were identified in herbarium material at the epithymum in central Europe (Stojanovich 1959), National Botanic Gardens, Dublin. over at least one winter period. The preferred hosts for Cuscuta epithymum It will be interesting to monitor the fate of throughout its range in Europe (Tutin et al. 1972) Cuscuta epithymum in its habitats in the Burren include Trifolium species, Calluna vulgaris and Ulex Lowlands. If the plant is newly introduced to the europaeus. Among the Irish herbarium specimens Cooloorta and Connell's Ford sites it is tempting to Ulex gallii rather than U. europaeus is a common host. speculate that it will extend its distributional area there. It should remain a permanent resident of the DISCUSSION low-growing grazed grassland, which is analogous to the sand-dune vegetation at Fanore in terms of There are two possible explanations as to why openness of structure and, to some extent, in species Cuscuta epithymum was not found in the inland parts composition. There are host species common to the of the Burren prior to 1990. Botanists up to that Fanore and Cooloorta sites, including Lotus time may have overlooked the plant in that area. corniculatus, Thymus praecox, Asperula cynanchica, Cooloorta is an interesting botanical site where Achillea millefolium, Trffolium pratense and Viola Ophrys insectrfera,0. apjfera, Plathanthera bjfoliata and species. Hosts of Cuscuta, known from elsewhere in Neotinea maculata coexist, where Potentilla fruticosa Ireland, such as Festuca rubraand Potentilla erecta also and fens are easily accessible, and where occur there. Botrychium lunaria has been located on several While it is evident from the information occasions (Doyle 1987). Despite frequent visits, presented here that Cuscuta is catholic in its including the early summers of 1988 and 1989, the selection of host plants at the Clare sites, its rarity species was not encountered at Cooloorta. It must in Ireland suggests that establishment is a critical be stressed that unless the plant occurs in massive factor determining its distribution. Establishment amounts, as is the case with the colonies on the depends on and infection of a dunes at Fanore, the species can be difficult to suitable host species, processes that in turn depend detect owing to its low-growing habit. This is on the suitability of the habitat and environmental especially the case in the early part of the growing conditions and the availability of host species. As season when the thread-like stems have just com vegetation communities are sensitive monitors of menced their development and the previous year's environmental and habitat factors, establishment of above-ground material has disintegrated. The plant Cuscuta may be restricted to particular vegetation ismost readily observed during its flowering period types. Once established on a suitable primary host from July to September, when it climbs stems of in vegetation containing a number of potential host hosts such as Achillea millefolium or Teucrium species, Cuscuta may then readily spread and scorodonia, so that the diminutive pink are become a permanent resident there. raised above ground level and become relatively obvious. Although the Burren is frequently visited by botanists, the majority arrive in the early summer ACKNOWLEDGEMENTS period (mid to late May) when the Burren specialities such as Dryas octopetala, Gentiana verna, I thank Mr Donal Synnott of the National Neotinea maculata and Ajuga pyramidalis are in Botanic Gardens at Glasnevin, Dublin, for allowing flower. As a result, late-flowering species in the access to the herbarium material of Cuscuta, and Dr region may be under-recorded. Noel Kirby (Connemara National Park, Letterfrack, Co. Galway) for information on the A second explanation is that Cuscuta has station for Cuscuta at Connell's Ford. I thank Dr recently arrived at Cooloorta and Connell's Ford, Lieveke van Doorslaer, and the participants in the through independent, chance introductions of Department of Botany, University College Dublin, . Kuijt (1969) considers that dispersal in Honours School Field Course in 1991 for their help Cuscuta is rather haphazard, and while seeds can pass in searching for the host plants for Cuscuta at through the intestinal tract of sheep unharmed, Cooloorta and Fanore, Co. Clare. animals as dispersal agents are generally unim portant. Discussion with local farmers confirmed that there is no movement of cattle between the REFERENCES inland sites and Fanore, and that cattle fodder is G. 1987 lunaria L. produced in the immediate vicinity of the inland Doyle, J. Botrychium is not always sites and is not transported from anywhere near the in its occurrence in Ireland. Irish capricious ' previously known site at Fanore. Naturalists Journal 22, 336-8. on Druce, G. C. 1909 Notes Irish plants. Irish Naturalists' At Cooloorta, Cuscuta is well established as it Journal 18, 209. has flowered extensively and has survived at the site, M. 1981 hostitele Frolisek, Plevele jako kokotice jetelove either as seed or as vegetative material on some host (Cuscuta trifolii). Preslia, Praha 53, 323-8.

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Gimingham, OH. 1972 of heathlands. London. Scannell, M. J. P. and Synnott, D. M. 1987 Census cata Chapman Hall. logue of theflora of Ireland. Dublin. Stationery Office. Hult?n, E. and Fries, M. 1986 Atlas of North European Smith, A. J. E. 1978 The moss of Britain and Ireland. vascular plants. K?nigstein. Koeltz Scientific. Cambridge University Press. C. Ivimey-Cook, R. B. and Proctor, M. F. 1966 The Stace, C. 1991 New flora of the British Isles. Cambridge plant communities of the Burren, Co. Clare. University Press. Proceedings of the Royal Irish Academy 64B, 211-301. Stojanovich, D. 1959 (A contribution to the study of the ? Kuijt, J. 1969 The biology of the parasitic flowering plants. biology of Cuscuta epithymum vegetative Berkeley and Los Angeles. University of California hibernation.) Zashtita Bilja 51, 47-9. Press. Turin, T. G., Heywood, V. H., Burges, N. A., Moore, Meusel, H.J?ger, E., Rauschert, S. and Weinert, E. 1978 D. M., Valentine, D. H., Walters, S. M. and Webb, Vergleichende Chorologie der Zentraleurop?ischen Flora. D. A. 1964-80 Flora Europaea, vols 1-5. Cambridge Jena. Fischer. University Press. on More, A. G. 1892 Note Cuscuta epithymum. Irish Turin, T. G., Heywood, V. H., Burges, N. A., Moore, Naturalist 1, 18. D. M? Valentine, D.H., Walters, S. M. and Webb, Mueller-Dombois, D. and Ellenberg, H. 1974 Aims and D. A. 1972 Flora Europaea. Vol. 3. Diapensiaceae to methods in vegetation ecology. New York. Wiley. Myoporaceae. Cambridge University Press. a to Nelson, E. C. 1991 The Burren: companion guide the T?xen, R. 1970 Die Pflanzengesellschaften Nordwest an wildflowers of Irish limestone wilderness. Kilkenny deutschlands. Lehre. Cramer. western and Dublin. Boethius Press and the Conservancy of Webb, D. A. 1947 Two new plant records. Irish the Burren. Naturalists' Journal 9',100. Nowers, J. E. and Wells, J. G. 1892 The plants of the Webb, D. A. 1962 Noteworthy plants of the Burren: a Aran Islands, Galway Bay. Journal of Botany 30, 380. catalogue raisonn?. Proceedings of the Royal Irish Oberdorfer, E. 1979 Pflanzensoziologische Exkursions Flora. Academy 62B, 117-34. Stuttgart. Ulmer. Webb, D. A. 1977 An Irish flora. Dundalk. Dundalgan Perring, F. H. and Walters, S. M. 1976 The atlas of the Press. British flora. London. Botanical Society of the British Webb, D. A. and Scannell, M. J. P. 1983 Flora of The subvention granted Isles. Connemara and the Burren. Dublin and Cambridge. by University College Rieley, J. and Page, S. 1990 Ecology of plant communities: Royal Dublin Society and Cambridge University a Dublin towards the cost phytosociological account of the British vegetation. Press. of publication of papers Harlow. Longman. Westhoff, V. and Den Held, A. J. 1975 Plan bymembers of its staff is Rodwell,J. S. (ed.) 1991 British plant communities. Vol. 2. tengemeenschappen inNederland. Zutphen. Thieme. gratefullyacknowledged Mires and heaths. Cambridge University Press. White, J. and Doyle, G. J. 1982 The vegetation of a by the Royal Irish Rothmaler, W. 1976 Exkursions Flora. Berlin. Volk und Ireland: catalogue raisonn?. Journal of Life Sciences Academy. Wissen Volkseigener. of the Royal Dublin Society 3, 289-368.

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