The biology of Canadian weeds. 128. Leucanthemum vu/gare Lam. · Asteracee, composees, tribe...

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The biology of Canadian weeds. 128.Leucanthemum vu/gare Lam.

David R. Clements1, Dan E. Cole2, Stephen Darbyshire,3 Jane King4, and Alee MeClayS

1Department of Biology, Trinity Westem University, Langley, British Columbia, Canada V2Y 1Y1; 2AlbertaAgriculture, Food and Rural Development, 6903 - 116 St., Edmonton, Alberta, Canada T6H 5Z2; 3Eastem

Cereal and Oilseed Research Centre, Agriculture and Agri-Food Canada, Wm. Saunders Building #49,Ottawa, Ontario, Canada K1A OC6; 4Department of AFNS, 4-10 Agriculture Forestry etr., University ofAlberta, Edmonton, Alberta, Canada T6G 2P5; 5Alberta Research Council, p.a. Bag 4000, Vegrevil/e,

Alberta, Canada T9C 1T4. Received 1 August 2002, accepted 11 September 2003.

Clements, D. R., Cole, D. E., Darbyshire, S., King, J. and McClay, A. 2004. The biology of Canadian weeds. 128.Leucanthemum vulgare Lam. Can. J. Plant Sci. 84: 343-363. Leucanthemum vulgare Lam. (Asteraceae), known as ox-eye daisy,is a familiar perennial herb with white ray florets and yellow disc florets. It commonly inhabits roadside verges, pastures and oldfields from Newfoundland to British Columbia, and also as far north as the Yukon Territory. Introduced from Europe, L. vulgarewas well established in North America by 1800. The Canadian distribution of L. vulgare has expanded in many areas recently,particularly in westem Canada. It can form dense populations that may reduce diversity of natural vegetation or pasture quality,and also serves as a host and reservoir for several species of polyphagous gall-forming Meloidogyne nematodes that feed on crops.It is considered a noxious weed under provincial legislation in Quebec, Manitoba, Alberta and British Columbia, as well as underthe Canada Seeds Act. Control efforts are sometimes complicated by difficulties in distinguishing ox-eye daisy from some formsof the commercially available Shasta daisy (L. x superbum).

Key words: Leucanthemum vulgare. Chrysanthemum leucanthemum, Leucanthemum ircutianum, Leucanthemum x superbum ,ox-eye daisy, CHYLE, marguerite blanche, Shasta daisy, Asteraceae, Compositae, pasture management

Clements, D. R., Cole, D. E., Darbyshire, S., King, 1. et McClay, A. 2004. La biologie des mauvaises herbes au Canada. 128.Leucanthemum vulgare Lam. Can. J. Plant Sci. 84: 343-363. La marguerite blanche, Leucanthemum vulgare Lam. (Asteracees),est une vivace bien connue avec ses fleurs ligulees blanches et ses fleurons jaunes. ElIe peuple couramment le bord des routes, lespaturages et les champs abandonnes de Terre-Neuve It la Colombie-Britannique, jusqu'au Yukon, dans le nord. Introduited'Europe,la marguerite blanche etait solidement implant6e en Amerique du Nord des le debut du dix-neuvieme siecle. Au Canada,son aire s'est recemment elargie dans maintes regions, principalement dans 1'0uest. L'espeee y forme parfois des peuplementsdenses qui r6duisent la diversite de la flore indigene ou la qualite des paturages en plus de servir d'Mte et de reservoir It plusieursespeees de nematodes polyphages cecidogenes du genre Meloidogyne qui s'attaquent aux cultures. Au Quebec, au Manitoba, enAlberta et en Colombie-Britannique, les lois provinciales la classent parmi les adventices nuisibles, comme le fait la loi canadienne sur les semences. La difficulte de differencier cette espeee de la marguerite Shasta omementale (L. x superbum), disponibledans le commerce, complique parfois les efforts de lutte.

Mots cles: Leucanthemum vulgare, Chrysanthemum leucanthemum, Leucanthemum ircutianum, Leucanthemum x superbum,marguerite blanche, achyleux, ox-eye daisy, marguerite Shasta, Asteracees, Composees, gestion des paturages

1. NamesI. Leucanthemum vulgare Lam.-Synonyms: Leucanthemumvulgare var. vulgare; Chrysanthemum leucanthemum L.;Leucanthemum leucanthemum (L.) Rydb.; Chrysanthemumleucanthemum var. subpinnatifidum Femald; ox-eye daisy,(Darbyshire et a1. 2(00), bull's eye (Boivin 1972), daisy(Boivin 1972), field daisy (Stearman 1983), Margueite(Frankton and Mulligan 1987), mid-summer daisy(Stearman 1983), moon-penny (Stearman 1983), poodandflower (Stearman 1983), poverty weed (Stearman 1983),white daisy (Frankton and Mulligan 1987), white-weed(Frankton and Mulligan 1987), marguerite blanche(Darbyshire et a1. 2000), bouquet blanc (Crompton et a1.1988), chrysantheme a fleurs blanche (Crompton et a1.1988), chrysantheme blanc (Crompton et al. 1988), chrysantheme des pres (Crompton et a1. 1988) chrysantheme

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grande-marguerite (Crompton et al. 1988), chrysanthemeleucantheme (Marie-Victorin 1997), grande marguerite(Alex 1992), leucantheme (Crompton et al. 1988), leucantheme commun (Orban 1885), marguerite (Boivin 1972),marguerite des champs (Louis-Marie 1931), oeil-de-boef(Crompton et al. 1988). Bayer code: CHYLE.

11. Leucanthemum vulgare var. ircutianum (DC.) KrylovSynonyms: Chrysanthemum ircutianum (DC.) Turcz.;Leucanthemum ircutianum DC.; Leucanthemum vulgaressp. ircutianum (DC.) Tzvelev; Chrysanthemum leucanthemum var. pinnatifidum Lecoq. & Lam.; Leucanthemumpraecox auct.; Chrysanthemum leucanthemum var. boecheriB. Boivin; tetraploid race (Bocher and Larsen 1957).

Asteraceae, Compositae, aster family (composite family),Asteracee, composees, tribe Anthemideae.

344 CANADIAN JOURNAL OF PLANT SCIENCE

An article by Heywood and Humphries (1977) broughttogether a considerable amount of infonnation pointing to theunnatural circumscription of many of the genera in the tribeAnthemideae. Bremer and Humphries (1993) conducted adetailed cladistic analysis of the tribe and further refined generic concepts into monophyletic groups. In a broad taxonomicsense, the genus Chrysanthemum contains about 200 species(Willis 1966), but with the assignment of many species to othergenera. Chrysanthemum is now considered to contain only 2-4annual species native to the Mediterranean area (Maberly 1987;SOl-eng and Cope 1991; Bremer and Humphries 1993). Thisrealignment of the generic limits has been fuelled by evidenceof relationships accumulated from seed anatomy and morphology, embryology, hybridization, and phytochemistry(Heywood and Humphries 1977; Bremer 1994). Summaries ofthe taxonomic realignment and nomenclature of the genus andits relatives are given by Anderson (1987) and Soreng andCope (1991) and a key to the genera of the Anthemideae isgiven by Bremer and Humphries (1993). The genus name thatshould be applied to ox~ye daisy is Leucanthemum Mill. 'Ibisgenus is considered to have about 26-33 species of perennialherbs that have red (or reddish brown) root tips. Species of thegenus occur naturally in Europe, North Africa and southwestern Asia. Under the International Code of BotanicalNomenclature, tautonyms are not allowed and so the nameLeucanthemum vulgare must be used for ox~ye daisy.

2. Description and Account of Variation(a) Physical description-L vu/gare is a glabrous to sparselypubescent shallow-rooted perennial herb with conspicuous terminal flower heads (Fig. 1). Roots arise from a short creepingrootstock with a curved main stem with many adventitiousroots. Underground stems contain water-soluble red pigmentsin the xylem and pith tissues. Either short rhizomes or stoutroot-crowns may give rise to stems" SeedHnp (Fig. 7) bearcotyledons that open above the soil surface; the hypocotyl doesnot continue to elongate above the ground (Fig. 2A). Stems areerect, simple or slightly branching with usually 1-2 per plant,but may form thick clusters (Fig. 2B). The stems arise fromstout rootstocks and are decumbent at their base, usually 30-90cm in height, reaching a maximum height of 2 ID. Leaves aresparsely pubescent and three-nerved. Basal leaves are stalked,spatulate (spatula-shaped) to obovate (egg-shaped with the narrower end at the base), and irregularly dentate (sharp teeth) toregularly crenulate (rounded teeth) (10-25 cm long and 3-7 cmwide). Stem leaves are smaller, alternate, mostly sessile, obovate to narrowly lanceolate (lance head-shaped) becoming ligulate (strap-like) apically with coarse teeth and the base usuallydeeply lobed or fringed with slender segments (fImbriate).Flower heads (capitula) are erect, usually solitary on long terminal peduncles and are (2) 2.5-7.5 cm in diameter, with 1-15inflorescences per plant The flower heads are mainly heterogamous with female ray florets and hermaphrodite disk floret$.White ray florets (Fig. IB) number 15 to 30 per head and are0.5-2.4 cm long, ligulate, the apex rounded or with 3 smallteeth; the 400 to 500 yellow disk florets (Fig. IC) are 4 mmlong and tubular forming a dense, slightly domed centre. Thenumerous involucral bracts (Fig. lE) are green, edged withbrown, and surround the base of each head. Plants with discoid

heads and lacking ray florets have been found in NewHampshire (Bogie 1983). Fruits (Fig. ID) from both disk andray florets are gray-silvery obovoid to cylindrical achenes(cypselas) with 5-10 equal raised ribs and are 2-3 mm long and0.8-1 mm wide. The pappus is absent or reduced to a crown.Pollen grain structure was described and illustrated by Nilssonet al. (1977). When crushed, all parts of the L vulgare planthave a disagreeable sour odour (Alex 1992).

Leucanthemum vulgare Lam. var. vulgare has a chromosome number of 2n =18; L vulgare var. ircutianum (DC.)Krylov is a tetraploid with 2n =36 (Table 1). Both chromosome races are present in Canada (Mulligan 1958).

(b) Distinguishing features-Although the flower of ox~yedaisy clearly distinguishes it from most herbs, there are otherplants with white ray florets and yellow disk florets includingscentless chamomile, Matricaria peiforata Menu [=Matricariamaritima L. vac. agrestis (Knat) Wilmottl, and stinking mayweed, Anthemis cotula L. (Frankton and Mulligan 1987). Theflower heads ofM. peiforata are smaller (2-3 cm in diameter)and the leaves are fern-like and finely divided (Cranston et al.1996). Anthemis cotula can be distinguished by the distinctivestem hairs below the smaller flower heads as well as the morefInely dissected leaves. It also has a distinctive odour. Englishdaisy (Bellis perennis L.) has a squat growth form, 2-20 cmtall, with elliptic to oval or circular leaves (Pojar andMacKinnon 1994). Some fleabanes (Erigeron spp.) also possess flowers with similar coloration, but the ligulate flowers aremuch narrower. Populations of L vu/gare can be detected byaerial remote sensing when in bloom (Lass and Callihan 1997).

The popular horticultural plant known as Shasta daisy,Leucanthemum x superbum (J.W. Ingram) D.H. Kent, wasdeveloped by Luther Burbank early in the nineteenth century.It is presumed by most workers to be a hybrid between L lacustre and L maximum (e.g., Ingram 1975). Hornback (1982), ,'however, indicated from Burbank's records that the development of Shasta daisy was much more complicated, involving"wild" plants of L leucanthemum from North America, Lmaximum, L lacustre and Nipponanthemum nipponicum(Maxim.) Kitam. (= Chrysanthemum nipponicum Maxim.).Since it was originally developed from hybridization ofspeciesmostly from within the L vulgare complex and because manycultivars have been produced subsequently (Homback 1982),some varieties (e.g., cultivar May Queen) can appear similar toox~ye daisies, especially tetraploid forms of the latter. Thethicker and more succulent leaves of Shasta daisy are coarselyand regularly toothed or crenulate and not deeply toothed orlobed as in ox~ye daisy. Stem leaves are not greatly reducedapically and, in the vast majority of varieties, are not lobed,fimbriate or pinnatifId at their base. Lower leaves are oblanceolate to 30 cm long including the petiole, which, if present, isusually winged. Upper leaves are lanceolate and sessile orslightly clasping. Flower heads are larger than in ox-eye daisy,being up to 10 cm or more across.

Shasta daisy is a hardy and popular garden plant in Canada.In spite of this, it rarely escapes cultivation and when established does not seem to persist. The only report that we havefound of establishment in Canada is that by Cayouette et al.(1983) at Sainte-Foy, Quebec (cf. Scoggan 1979; Boivin 1966),

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CLEMENTS ET AL - LEUCANTHEMUM VULGARE LAM. 345

Fig. 1. Leucanthemum vulgare, ox-eye daisy (from Anonymous 1970). A: habit, bar =1 cm; B: ray flower (ligulate flower), bar =I cm; C:disk flower (tube flower), bar (next to B) =1 cm; D: achenes, bar =I mm; E: involucra! bracts; bar =1 mm.

where it was probably introduced through dumping of gardenwaste (J. Cayouette, pers. comm.). It may be that the plantreported by Kucyniak (1945) from Lachine, Quebec, is also afonn of L x superbum.

(c) lntraspecific variation-The ox-eye daisy is part of alarge species complex that ranges through most of Europeand western Asia. The remarks by Heywood (1976) in FloraEuropaea provide an excellent summation of present taxo-


Fig. 2. Leucanthemum vulgare. A. Seedling with cotyledons and first two UUe leaves; bar = 1 cm. B. Young rosette; bar = 1 cm.

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nomic understanding of this group. "An extremely variablespecies or species-complex which has been divided into alarge number of taxa (given the rank of variety, subspeciesor species) many. of which are of restricted occurrence. Thediscovery of extensive cytological variation has led to intensive cytotaxonomic studies of the populations in variousparts of Europe. Although some regional and local correlations between chromosome number and morphological variation can be detected, no overall treatment is at presentpossible and the recent tendency to recognize the variouscomponents of this complex as species is certainly premature and cannot be justified on practical grounds with ourpresent knowledge. Since, however, it is desirable to drawattention to the main variants that deserve some recognition,they are listed below." Fifteen of these named "variants" arethen listed without a key for their identification:Leucanthemum praecox (Horvati) Horvati, L. leucolepis(Briq. & Cavill.) Horvati, L. adustum (Koch) Gremli, L. heterophyllum (Willd.) DC., L. cuneifolium HJ. Coste, L. maximum (Ramond) DC., L. pallens (Gay) DC., L. crassifolium(Lange) Willk., L. subglaucum De Laramb., L. meridionaleLegrand, L. laciniatum Huter, Porta & Rigo, L. delarbreiTimb.-Lagr., L. lacustre (Brot.) Samp., L. sylvaticum(Hoffmanns. & Link) Nyman, L. pluriflorum Pau.

Of the segregates in the L. vulgare species complex, thename L. praecox has sometimes been applied to tetraploid racesof ox-eye daisy in Canada, although Heywood (1976) statesthat this taxon is diploid. The name L. vulgare var. ircutianum(DC.) Krylov was applied to tetraploid forms by B6cher andLarsen (1957). In the Canadian literature this latter name hassometimes been applied to tetraploids, or, if the name L. praecox is used, L ircutianum is listed as a synonym. There are differences in morphology and flowering time between thedifferent chromosome races (Fernald 1903; Mulligan 1958),but intennediate populations are known in Europe. Taxonomicdistinction at a subspecific rank between the chromosome racesin Canadian populations seems more reasonable than speciesranking, at least until there is a better understanding of theentire L vulgare species complex. Tzvelev (1995) noted thatthroughout the range of the species there are many regional biotypes. varying in morphological characteristics such as pubes-

cence and leaf shape. He discounted all these forms (includingvar. ircutianum) as being without taxonomic significance.Table 1 gives the main distinguishing characteristics betweenthe two chromosome races present in Canada.

Infraspecific taxonomy of ox-eye daisy in Canada has beenconfused by the varying applications of the name var. pinnatifidum. North American material of the diploid forms has sometimes been referred to under the name L. vulgare var.pinnatifidum (Lecoq & Lamotte) Moldenke (= C. leucanthemum var. pinnatifidum Lecoq & Lamotte) (e.g., Scoggan1979). B6cher and Larsen (1957), however, stated that thistaxon (described from southern France) is tetraploid and mightbe most closely allied to L vulgare var. ircutianum. LOve andBemard (1959) recognized tetraploid plants as a distinctspecies, and applied the name L. ircutianum var. pinnatifidum(Lecoq & Lamotte) D. LOve & I.-P. Bernard to this material.Under the impression that the tetraploid fonn represented thetype, Fernald (1903) coined the superfluous name C. leucanthemum var. subpinnatijidum Fernald to apply to the diploidforms introduced to North America

Ox-eye daisy is an extremely variable species. A variant withshallower leaf indentation is occasionally observed in theAtlantic provinces (Frankton and Mulligan 1987). Distinctmaritime and high mountain ecotypes are found in Europe(Salisbury 1961). BogIe (1983) found a plant in NewHampshire with inheritable discoid heads without ray florets.Five subspecies and many additional variants were recognizedby Howarth and Williams (1968) in central Europe. BOcher andLarsen (1957) regarded diploid (2n =18) and tetraploid (2n =36) forms as separate species, L. vulgare and C. ircutianum,respectively. The tetraploid race has a slightly larger flowerhead diameter and regularly toothed lower leaves, whereas thediploid race has irregularly alternating lobes or teeth on thelower leaves (Table 1). Kumar (1982) also distinguishedbetween the two distinct groups of L vulgare by flower size.He theorized that tetraploidy might have arisen through thediploidization of autopolyploids rather than by hybridizationand subsequent doubling of chromosomes. Mulligan (1968),examining diakinesis in pollen mother cells of tetraploid plantsin Quebec, found one to four quarivalents, leading him to conclude that they were probably autotetraploid. BOcher and


Table 1. The differences between cbrolllOSOllle races of LeucanJltemlllft vuIgan present In Canada [after Femald (1903), BOcher and Larsen (1957),MulIipn (1958) and this paper]

Category Leucanthemum vuIgare Lam. var. vulgare

Chromosome number Diploid, 2ft = 18

Leucanthemum vulgare var. ircutianum (DC.) Krylov

Tetraploid, 2ft = 36

Heads (capitula)

Basal leaves

Lower stem leaves

Middle andupper stem leaves

Pollen size(inside diameter)

Usually solitary;4-7 cm in diameter

Spatulate, coarsely and irregu1arly toothed orlobed,often fimbriate basally

Narrowly spatulate, irregu1arly serrate ordentate, lacerate, lobed or shallowly pinnatebasally

'Narrowly oblong or oblaoceolate, irregularlycoarsely toothed, usually distinctly fimbriateor somewhat pinnate (subpinnatifid) basally

11.7-23.4 J.UIl16.7 J.UIl (average)

Often more than ooe per stem; 5-7.5 cm in

diameter Spatulate-ovate., closely and R:gularlyCR:nate, rarely lobed or fimbriate basally

Broadly spatulate to broadly ovate, R:gularlycoarsely crenateor dentate, coarsely toothedbasally with spreading teeth

Oblong to oblaoceolate, R:gularly coarsely,toothedlarger teeth basally but not fimbriateorpiooate

13.7-27.3 J.UIl18.9 J.UIl (average)

Larsen (1957) found that the diploids were more prevalent inNorthwestern Europe whereas the tetraploids dominated innortheastern Europe and the southern European mountains. Insome areas such as Norway and central Europe, the races areintermixed (Favarger and Villard 1965; Knaben 1982), butFavarger and Villard (1965) found that diploids begin flowering earlier than tetraploids and that the races occupy slightlydifferent habitats. Fernald (1903) first reported the morphologically different tetraploid form as being restricted to easternCanada and noted its similarity to the common form in centralEurope. Mulligan (1958, 1968) found that the diploid_race wasmost prevalent and widespread throughout North America Hefound that the tetraploid l1lce was locally common only insouthern Quebec and Nova Scotia, but reported examiningspecimens collected from Labrador, Ontario, Manitoba, BritishColumbia, Minnesota and Washington. LOve and Bemard(1959) reported that the tetraploid fonn was most common atOtterbume, Manitoba, while the diploid was found to be rare inthat area. Hexaploid and octaploid races occurring in Europehave sometimes been considered separate species,Leucanthemum graminifolium (L.) Lam. (= L. montanum (L.)DC.) and L. heterophyllum, respectively (Favarger 1959).

Mulligan (1958), reported that pollen size was differentbetween plants of varying ploidy level (diploid: 16.3-19.5J.l.m; tetraploid: 19.5-22.8 J.l.m; and hexaploid: 22.8-24.4J.l.m). Pollen size was measured from specimens at the DAOherbarium of cultivated Shasta daisy and some of the oxeye daisy voucher specimens from Mulligan's chromosomestudy (Mulligan 1958). The two purported parents ofShasta daisy (L. maximum and L. lacustre) are high polyploids, 2n =90 and 198, respectively (Heywood 1976;Dowrick 1952) and chromosome counts of cultivated fonns(often reported under the name C. maximum) are also high.Counts from garden fonns have been reported as 2n =85,90, 126, 148, 154, 160 and 171 by Dowrick (1952), 2n =153 by Shimotomai (1938) and 2n =54 by Baksay (1960).Some of these counts may be based on garden forms of L.maximum in the strict sense, especially the decaploids.Although the correlation between chromosome number and

cell size in polyploid series between species can be misleading, and chromosomes decrease in size with increasingploidy in Chrysanthemum (sensu lato) (Dowrick 1952), asignificant difference in pollen size was found between oxeye daisy and Shasta daisy (Figs. 3-4). Following themethodology of Mulligan (1958), we repeated the measurements on the inside diameter of pollen grains from specimens at DAO previously studied and annotated by him.Diameters were found to range from 11.7 to 23.4 J.l.m (16.7JlID average) for diploid ox-eye daisy (21 collections), from13.7 to 27.3 W:JJ (18.9 JlID average) for tetraploid ox-eyedaisy (10 collections), and from 13.7 to 42.9 J.l.m (26.5 J.l.maverage) for Shasta daisy (27 collections not studied byMulligan». Chromosome counts are not known for the cultivated forms examined, but the large size of pollen cellsclearly reflects a significant difference in ploidy. Unlike thedata reported by Mulligan (1958), a substantial overlap in "pollen size range was observed (Fig. 4A). although meansize was significantly different (99% LSD) between ploidylevels (Fig. 4B). Although only 31 specimens were examined by us, compared with more than 191 by Mulligan, thedata presented here are consistent with the overlapping sizeranges between ploidy levels reported by BOcher andLarsen (1957).

Some cultivars sold as Shasta daisy, such as May Queen,are similar to tetraploid fonns of ox-eye daisy, and may infact be a sterile form of that taxon. The average pollen sizeof May Queen (20.7 JlID; range 15.6-27.3 JlID) was withinthe range of both ploidy levels of ox-eye daisy. Ox-eyedaisy has well fonned pollen, which stains well with lactophenol cotton blue (viability estimated at about 90%) (Fig.3 A,B). May Queen, on the other hand, was found to havemany misshapen and poorly stained pollen grains, suggesting a viability of much less than 50%. Furthermore, MayQueen does not appear to produce viable seeds. Nurseriesand gardeners do not report seed production in any of thevarieties of Shasta daisy available in Canada. However,viable seeds are occasionally produced in some cultivars(Ingram 1975; Homback 1982). The cultivation of diploid


FIg. 3. Pollen grains stained with laetophenol cotton blue; bar = 20 J.IID for all photos. A. Leucanthemum vu/gaTe var. vu/gare, 2n= 18 (J.M. Gi/lett47, DAD 4(4975). B. L vu/gaTe var. ircutianum, 2n= 36 (B. Boivin 1049, DAD 4(4419). C. Lx superbum, unknown ploidy (J. Roy 3636-59,DAD 405275).

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and tetraploid races of ox-eye daisy is also popular inCanadian gardens. Not only is ox-eye daisy sometimes dugfrom wild populations, but it is also available from manyseed companies. Gardens observed with transplanted ox-eyedaisy, rather than Shasta daisy, usually have evidence ofviable seed production; volunteer plants tend to escape thebeds and spread readily.

(d) lllustrations-A mature plant, ray and disk florets, achenes and involucral bracts are illustrated in Fig. 1. Seedlingsare illustrated in Fig. 2. Pollen variation is illustrated in Fig.3. An illustration of a heavy infestation of L vulgaTe is provided in Fig. 5. Additional illustrations are found inFrankton and Mulligan (1987).

3. Economic Importance(a) Detrimental-L vulgare does not generally cause majorproblems in annual crops in North America because its shallowroot system is vulnerable to cultivation (Olson and Wallander1999). In general, the ecological, environmental, economic andsociological impacts of L vulgare are not well known (Olsonand Wallander 1999). Holm et al. (1997) reported L vulgare asa weed of 13 crops in 40 countries, in addition to its role as amajor pasture w~. Contrary to Holm et al. (1997), L vulgareis not usually reported to be a problem in annual crops inCanada. It is known to infest cereals in Austria and Tunisia.legumes in Tunisia and corn (Zea mays L.) in South Africa(Holm et al. 1997). Smith et al. (1999) found that in England,where L vulgare was sown into uncropped field margins being

FIg•.4. Leucanthemum pollen size variation. A. Pollen size (inside diameter) in diploid and tetraploid Leucanthemum vulgare and L. x superbum cultivars. Boxes enclose the middle 50%, horizontal line indicates the median, vertical error bars indicate quartiles to within 1.5interquartile range and the single oudier is plotted individually. B. Factor means (99% LSD) of pollen size (inside diameter) in diploid andtetraploid Leucanthemum vulgare and L. x superbum cultivars.

managed for biodiversity, it occasionally spread a short distance into adjacent cropped areas. However, they did not consider this to present any risk to crop production. It readilypopulates pastures, rangelands and roadside areas, where itreduces plant species diversity and hay or forage production(Olson and Wallander 1999). Fields become white with theflower heads of L v.ulgare (Fig. 5). Once plants have established, the achenes may be spread widely as a contaminant inpasture seeds, hay or manure (Mitich 2000). Because of the relatively shallow root system of L vulgare in comparison tothose of perennial grasses, large populations ofL vulgare render areas vulnerable to soil erosion and deplete soil organicmatter. In general, L vulgare is avoided by cattle, and thusgrazing encourages its proliferation (Olson and Wallander1999). Milk from dairy cattle that have consumed L vu/garemay have a disagreeable taste (Frankton and Mulligan 1987).Gall-forming nematodes (Meloidogyne spp.) will use L vulgare as a host (Townshend and Davidson 1960, 1962;Davidson and Townshend 1967; Belair and Benoit 1996;Mauch and Ferraz 1996), and thus L vulgare may act as areservoir for these pests (see also section 13). L vulgare is oneof the ''priority exotic invasive species" for control inYellowstone National Park: (0l1iff et al. 2(01).

The mosquito Aedes aegypti L. is attracted to the odour ofL. vulgare flowers and feeds on their nectar (Jepson andHealy 1988), but a methylene chloride extract of the flowersis not attractive to another mosquito species, Culex pipiensL. (Mauer and Rowley 1999). L. vulgare is a strong sensitizer in guinea pig tests, suggesting that it is likely to cause

allergic contact dermatitis (Zeller et al. 1985). Many speciesin the tribe Anthemideae produce sesquiterpene lactonesand this class of compounds has been implicated as a causeof contact dermatitis (Mitchell et al. 1971). A few caseshave been reported, both in Europe and North America,where ox-eye daisy has been a cause of contact dematitis(Mitchell and Rook 1979). Although the pollen is not airborne, occasional cases of hay fever symptoms have beenreported after direct contact (Wodehouse 1935).

There are increasing concerns that escaping Shastadaisies may hybridize with L vulgare, or be confused withL vulgare where they grow. An "ox-eye daisy task force"based in Alberta made the following recommendations tohorticulturalists in 2000: prevent seeding of all whitedaisies, avoid buying wildflower seed mixes, buy Shastadaisy grown from cuttings-not seeds, choose other typesand colours of daisies or perennials, do not exchange any"naturalized" daisies, and set up displays in garden centresand other appropriate locations to educate people aboutinvasive plants and the concern over ox-eye daisy specifically (eole, pers. obs.).

(b) Beneficial-The aesthetic appeal of L vulgare is wellknown. Mitich (2000) wrote that it has been "beloved by princeand peasant in the Orient and the Western world" as seen in theinnumerable folk names it has been given throughout theworld. It is often intentionally spread as an ornamental andgrown in decorative gardens (Tzvelev 1995; Holm et al. 1997;Olson and Wallander 1999) and is a reported parent of the


Fig. 5. Leuconthemum vulgore infestation of pasture land at a site in Alberta.

'.

Shasta daisy. It is often included in commercial "wild-flower"seed mixes, and is well suited for bouquets.

L vulgare has been used to produce both infusions prescribed for internal disorders and lotions to apply to externalwounds and sores (le Strange 1977). Fresh flowers distributed on floors were used in Europe during the medievalperiod to repel fleas. Taken internally, extracts of L vulgareare valued for their antispasmodic, diuretic and tonic qualities. It was utilized in England for treatment of running eyes,cholera, ulcers and "as an application to the secret parts"(Culpeper 1953). L. vulgare infusions are still prescribed byherbalists for treatment of asthma, whooping-cough andnervous excitability, and lotions are recommended forulcers and sores (le Strange 1977).

Young leaves are occasionally incorporated into salads(le Strange 1977) and a 100 g sample of leaves from L vulgare contains more than 500 units of vitamin A (Zennie andOgzewalla 1977). More mature leaves have an acid flavourand the flowers are bitter. According to Fernald et a1.(1958), "Some European authors state that the young leavesof the Ox-eye Daisy make a palatable salad.... The odor ofour plants suggests, however, that fondness for this particular salad is an acquired taste."

Areas with large populations of L vulgare provide habitatfor wildlife. For example, spiders use them as hunting sites(Morse 1999). L vulgare is one of the species commonly sownas a means of maintaining biodiversity within agricultural land,such as in "ecological compensation areas" in Switzerland(Keller and Kolhnann 1999) and in species-poor grassland inEngland (Coulson et al. 2(01). It is also one of the species usedin wildflower seed mixes sown on fonner arable land. roadsides and land adjacent to developments in the UnitedKingdom (Speannan et al. 2(00). The flowers attract somebeneficial insects; L vulgare is among the most attractiveplants to adult syrphid flies, whose larvae feed on aphids

(Weiss and Stettmer 1991). However, the flowers were notfound not to be a suitable nectar source for the parasitoid waspPimpla turionellae L. (Wiickers et al. 1996). Powdered inflorescences ofL vulgare added to grain at 2% are effective repellents for grain weevil, Sitophilus granarius L., and rice weevil,S. oryzae L. (lgnatowicz 1998). Because it is intolerant ofheavy metals, L vulgare has been successfully used to monitorlevels ofPb, Zn. MD, Cu, Cr and Cd along a heavily used highway in Italy (Badino et al. 1998).

(c) Legislation-L. vulgare is classed as noxious withinAlberta under the Alberta weed control act (Anonymous1991) and in Manitoba under the Noxious Weed Act(Anonymous 1996). In British Columbia, L. vulgare is classified as noxious within the Cariboo, North Okanagan andPeace River districts, but not within other parts of theprovince (Cranston et al. 1996). It is listed as a noxiousweed in Quebec in the Agricultural Abuses Act (DivisionIV-Noxious Weeds) whether it occurs in agricultural lands(cultivated fields and pastures) or in ruderal habitats (transportation corridors, vacant lots, etc.) (Anonymous 1981). Inthe Canada Seeds Act (Agriculture Canada 1986) it is listedas a Class 2 Primary Noxious Weed Seed for most crop seedcommodities and as a Class 5 Noxious Weed in turf andgroundcover seed commodities. No L vulgare seed is permitted in Canada Foundation, Registered or Certified seedof most crop categories. It has also been declared noxious inother parts of the world (Holm et al. 1997).

4. Geographical DistributionThe present distribution of L. vulgare is throughout southernCanada from Newfoundland and Labrador to BritishColumbia, and as far north as Dawson City in the YukonTerritory (Fig. 6). Porsild and Cody (1980) reported it from"near Ft. Smith", but the specimen on which this report was


Fig. 6. Distribution of Leut:anthemum vulgare in Canada. Locations based on herbarium specimens from the following herbaria (abbreviations according to Holmgren et al. 1990): ACAD, ACK, ALTA, APM, CAN, DAO, LKHD, MMMN, MT, MTMG, LRS, NBM, NFLD,NSAC, NSPM, OAC. QFA, QUE, RBCM, SASK, TRT, OBe, UNB, UPEI, QFA, UVIC, UWO, WAT, WIN, WLU.

based was not located. Other than this reference, it has notbeen recorded from the Northwest Territories or Nunavut.As recently as the 1980s, it was referred to as "rare in mostof Alberta" (Frankton and Mulligan 1987). It is now fairlycommon in western, west-central and northeastern Alberta,and also occurs in the Peace River region (L. Darwent, pers.comm.; Frankton and Mulligan 1987). It is common insouthern areas of British Columbia, Ontario and Quebec andin the Maritime Provinces. In a weed survey of spring cereals in New Brunswick conducted in the late 1980s, L vulgare occurred in 54% of fields surveyed and ranked fourthin terms ofrelative abundance (Thomas et al. 1994). Frick etal. (1990), surveying weeds in southwestern Ontario underdifferent tillage regimes, found ox.:eye daisy at low frequencies in soybean fields under conventional tillage (1.4% frequency). It was not detected in reduced tillage systems norin corn or wheat crops.

Widely distributed throughout the United States, it isespecially common in the northeastern states and in northernstates down to California (Muenscher 1955), but is lesscommon in southern states (Olson and Wallander 1999).Taylor (1990) referred to L. vulgare as the most common

roadside weed in the Pacific Northwest, where the range ofL. vulgare continues to expand (Olson and Wallander 1999,R. Cranston, pers. comm.).

Native to Eurasia, L vulgare is found from northern Italyto Scandinavia (Howarth and Williams 1978) and extendseastward through Russia and central Asia (Hulten and Fries1986). From Eutope, it has been introduced to many otherparts of the world, including North America, SouthAmerica, New Zealand, Australia, Hawaii, Tunisia, Chinaand Pakistan (Holm et al. 1979).

5. Habitat(a) Climatic requirements-In both North America andEurope, L vulgare thrives in a variety of climatic regimes,living as far north as 700 N in Scandinavia (Howarth andWilliams 1968). Baldwin (1958) reported it to be quiteabundant in the Ontario-Quebec clay belt just south ofJames Bay. Although more abundant in moist climates, Lvulgare is drought-tolerant, and often colonizes habitatssubject to soil drying late in the season (Grime et al. 1988;Olson and Wallander 1999). It is tolerant of light frost whenactively growing (Olson and Wallander 1999).


(b) Substratum-In general, L vulgare tolerates a relativelywide range of soil types (Olson and Wallander 1999).Howarth and Williams (1968) noted that in Great Britain Lvulgare was widespread on both nutrient-rich clays and inlimestone grasslands where it is more common on basic orneutral soils than in acid soils. Ferdinandsen (1918) classedit as a basophile growing best at pH 6.5 to 7.0. In westernAlberta, L vulgare grows well in pasture land with a pH of5.9-6.1 (Cole 1998). Soil fertility levels have limited effectson growth of L vulgare and its nitrogen requirement isdescribed as moderate (Howarth and Williams 1968; 01sonand Wallander 1999). In fact, L vulgare frequently growsbetter on poor soils (Sanders 1993; Cole 1998).

When growing under moist conditions, the short rootstock ofL. vulgare can elevate the roseUe above the soil surface, with the adventitious roots stabilizing the plant. Theseedlings are relatively drought tolerant (Mitich 2000).Drought tolerance is illustrated by observations of the deeper-rooted Taraxacum officinale Weber (dandelion), whichhas been observed wilting before adjacent plants of L vulgare (Howarth and Williams 1968).

(c) Communities-L vulgare occurs mainly on roadsides,native grasslands, rangeland, pastures, hay fields, abandonedcroplands, railway embankments, rocky shores, rock outcrops,forest openings and waste ground but also is found in cultivated land, gardens and lawns (Dorn 1984; Alex 1992). Thediploid form has been observed to be more shade tolerant andassociated with mesic conditions, whereas the tetraploid formwas associated with more ruderal habitats, such as dry disturbed areas and roadsides (p. Morisset. unpublished). Grime etal. (1988) recorded the most common habitats whereL vulgareoccurred in Europe as 28% limestone quarries, 19% meadows,15% limestone wasteland, 14% cinder heaps and 9% rock outcrops. It is not common on cultivated land. It also grows sparsely in thickly vegetated areas because of its low shade tolerance(Olson and Wallander 1999). In an abandoned pasture in southern Ontario, Reader (1991) observed that L vulgare was moreabundant on ridges than in more densely vegetated hollows.Howarth and Williams (1968) list 25 frequent associates of Lvulgare in the United Kingdom, including species it also associates with in Canada such as Achillea millefolium L.,Centaurea nigra L., Hieracium pilosella L., Leontodon autumnalis L., Plantago lanceolata L., Prunella vulgaris L.,Ranunculus acris L., Rumex acetosa L., Taraxacum officinale,Trifolium pratense L., and T repens L.

6. HistoryThe recorded history of ox-eye daisy dates back to FarEastern legends (Mitich 2000). In Europe, achenes havebeen identified in excavations dating to the Iron Age and theRoman period (Howarth and Williams 1968). According toHowarth and Williams (1968), it appears to have spreadalong with increasing habitation of Europe. A common plantin Europe, L. vulgare was widely used in medieval medicine(see section 3b). The English name, ox-eye daisy, firstappeared in print in The Academy of Armory by RandleHolme in 1688 (Mitich 2000). Margaret of Anjou had oxeye daisies embroidered on her robes and those ofher aUen-

dants before sailing to England in 1445 to marry Henry VI.Subsequently, she led his troops in the Wars of the Roses,with her banners bearing the image of the daisy (Haughton1978). Later, as a result, it acquired the name "Marguerite."A woody relative from the Canary Islands, Argyranthemumfructescens (L.) Schultz-Bip. (= Chrsyanthemum fructgescens L.), is also called marguerite, Paris marguerite orParis daisy. This similar species may also have had a role intheori~nsoftheembkm.

Frankton and Mulligan (1987) reported that 'L vulgarewas introduced from Europe "at a very early date."According to tradition, it was an escape from GovernorEndicott's garden in Massachusetts (Haughton 1978). Itarrived in North America both as a contaminant in seed andas an ornamental, becoming naturalized first in the northeastern United States (Olson and Wallander 1999). By 1785,it was known as a problematic weed around Boston (Fernald1903). By 1800, L vulgare was well established throughoutmany re~ons of North America, and it was utilized extensively in herbal medicine during the nineteenth century. Itwas introduced into the northwestern United States as a contaminant of forage and grass seeds in the late 1800s and by1937 it occurred in more than 50% of northwestern UnitedStates counties (Forcella 1985).

The rapid spread of L vulgare throughout North Americawas facilitated by moist. disturbed conditions within roadside ditches, which facilitated the spread of seeds via air andwater (Howarth and Williams 1968). As mentioned previously, the penetration of L. vulgare into drier re~ons ofNorth America, such as the interior plains, has been lessrapid as it is reliant on favourable agricultural practices,such as irrigation of pasture land. Substantial populationshave only developed recently in Alberta (in the last severaldecades), and it does not seem to be a weed of concern inSaskatchewan (D. Cole, pers. obs.).

7. Growth and Development(a) M01phology-Howarth and Williams (1968) describedox-eye daisy as a shallow-rooted perennial herb that spreadsby rhizomes and seeds. Germination is epigeal with the pericarp carried above the ground. The seedling root systemstarts to be replaced by a well-developed system of relatively shallow lateral roots at about the 6-leaf stage (Howarthand Williams 1968). There is limited rooting of more prostrate basal stems or rhizomes. Subsequent to the development of basal stem rooting, the main root system is reducedin importance.

In a greenhouse experiment, L vulgare seedlings growingat 201l8°C day/night temperatures were 2 to 5 cm tall with4 to 7 leaves at 16 d after seeding. After 5 wk of growth, theplants were 7 to 12 cm tall with 5 to 10 basal vegetativebranches and 24 to 56 leaves. At 15 wk, plants had as manyas 55 basal branches and 319 leaves (Cole 1998). In a fieldexperiment in Alberta, seedlings that germinated in earlyJuly had reached a height of 18 cm with 24 basal stems bymid September (Cole 1998).

When growing as single-spaced plants, at the end of twogrowing seasons, individual ox-eye daisy plants hadattained a volume of 0.68 m3 and produced an average of 75

".

· .

CLEMENTS ET AL - LEUCANTHEMUAf VULGARE LAM. 353

stems and 392 flower heads per plant. In the same test,plants growing in competition with meadow bromegrass(Bromus riparius Rehm.) were one-tenth the volume with7.5 stems and 26 flower heads (King and Cole, unpublisheddata). In Australia at an altitutude of600 m, the leaf life spanwas 66 d as compared to 42 to 95 d for other low altitudeperennial herbaceous plants (Diemer et al. 1992).

Many features of L vulgare show xeromorphic adaptation, such as having leaves with stomata on both sides, anda tendency toward succulence (Howarth and Williams 1968;Grime et al. 1988). Biotypes adapted for salt-spray conditions on the coasts of the United Kingdom retained theircharacteristic features when cultivated (Howarth andWilliams 1968). The xeromorphic characteristics were alsoinduced in response to nitrogen shortage.

The flower heads are usually solitary on long terminalpeduncles and are 2.5 to 7.5 cm in diameter. In pastures, thereare typically one to three flowering stems per plant, though asingle plant growing in the absence of competition can produce more than lOO stems (Cole and King, unpublished data).

(b) Perennation-Classed as a hemicryptophyte, L vulgarereproduces by seed and by limited rooting and budding atthe decumbent bases of the stems, both above and below thesoil surface (S. Darbyshire, unpublished data). Extendedspread is by seeds from second and subsequent year flowering plants. Both the plant and its achenes are able to overwinter, but seeds only persist under certain environmentalconditions (see section 8c).

(c) Physiology-Heide (1995) described a dual inductionrequirement for flowering. The primary induction is a lowtemperature vemalization response, the optimum temperature being 6-9°C. Subsequently, a period of long daysinduces inflorescence initiation and stem elongation.Approximately six weeks of exposure to vemalization wasrequired for 100% flowering. Long days (LD) were requiredfor inflorescence initiation and stem elongation at 9°C.More than 16 LD cycles were required for normal stemelongation (bolting).

L vulgare is able to adjust leaf position through modulations in petiole development (Howartb and Williams 1968).When grown under shade cloth at 24% of full light intensity, plants devoted energy to reproduction at the expense ofroot growth and production of late-season leaves (Boutinand Morisset 1988). .

Bungener et al. (1999) found that L. vulgare was sensitiveto ozone concentrations of double the ambient level, exhibiting decreased biomass in the ftrst year of growth. In contrast, Mortensen and Nilsen (1992) found that L vulgarebiomass did not decrease with exposure to enhanced ozonelevels, but exposed plants did exhibit chlorosis.

Seeds are rich in linoleic acid and, while devoid of starchand tannins, contain 24% protein and 26% fats (Earle andJones 1962). Surface extracts from L. vulgare flowers contained the flavonoids apigenin, acacetin, and apigenin 7-g1ucuronide, while extracts from leaf and flower tissuecontained acacetin 7-diglucuronide, apigenin 7-g1ucuronide,kaempferol 5-g1ucoside, kaempferol 5-g1ucuronide, luteolin

7-g1ucuronide, quercetin 5-g1ucoside, quercetin 5-g1ucuronide, quercetin 7-g1ucoside, and quercetin 7-g1ucuronide. The relative proportions of these compounds maybe of taxonomic value (Williams et al. 2(01). The presenceof the cyclitol L-leucanthemitol was reported by Plouvier(1963). Sagareishvili (2000) isolated a variety of compounds from the flowers of plants growing in the country ofGeorgia, including: the flavonoids apigenin, cosmosiine,apigenin 7-O-P-D-glucuronide, vitexin, rutin, hyperin,quercetin, luteolin, isorhamnetin, chrysin 7-0-P-D-glucuronide and chrysin; four methylsterols, the principal onebeing 24-ethylidenelophenol; the pyrrolizidine alkaloidsplatiphylline and senecionine; and choline.

(d) Phenology-The majority of ox-eye daisy seeds germinatein the spring, with sporadic germination throughout the growing season (Howarth and Williams 1968). In the ftrst year ofgrowth, the plant forms a vegetative basal rosette, typicallyunder 5 cm in height. In the second and subsequent years, flowering stems are produced. L vulgare is an obligate long-dayplant (Spector 1956). Bolting and flowering typically occurfrom June to August, though in Quebec, Boutin and Morisset(1989) observed that flower production continued intoSeptember. Seedling plants have a short juvenile phase of onlyfour weeks. In west-eentral Alberta, heavily infested hay andpasture land may be completely white with L vulgare in July(J. King, pers. ohs.). After the development of flowering stems,a further increase in rosette leaves may be observed towards theend of July in Quebec as the plant puts energy into perennatingstructures that will survive the winter (Boutin and Morisset1989). Seeds are shed in August and September when the inflorescences are senescent and desiccating. In late fall, most plantsdie back to the crown, though in milder climates the basalrosette leaves can persist throughout the winter.

(e) Mycorrhiza-Kuehn et al. (1991) observed L vulgare to beheavily infected with vesicular-arbuscular mycorrhizae (VAM)inGennany.

8. Reproduction(a) Floral Biology-L vulgare is chiefly insect-pollinated.Outcrossing is promoted by a male stage preceding the femalestage (protandry) within the disk florets (Howartb andWilliams 1968), but there is a possibility of automatic self-pollination (Knuth 1908; Grime et al. 1988). Ifnot pollinated earlyby insects, the stigmas will recurve towards the anthers as thestigmas are self-pollinated as they mature. The disk florets contain nectar, and during the male stage, the brushes on the styledirect the pollen up the anther tube. Marie-Victorin (1997) stated that, although the flowers are nectiferous, they are not visited by honeybees, but only by small insects. Regardless,reported pollinators of L vulgare include bees from theHalictidae and Anthophoridae, as well as Diptera (especiallyCalliphoridae, Conopidae, Stratiomyidae, and Syrphidae),Lepidoptera, and Thysanoptera (Howarth and Williams 1968;Ginsberg 1984). Dicks et al. (2002), in England, found that themost common insect visitors to L vulgare flowers were thebumblebee Bomhus lapidarius (L.), the flies Empis livida L.,Eristalinus sepulchralis (L.), Helophilus sp., Tropida scita, and


Phaonia incana (Wiedemann), and the butterfly Maniolajurtina (L.). Knuth (1908) reported more than 100 species ofColeoptera. Hymenoptera. Diptera and Lepidoptera visitingox-eye daisy in central Europe. He also cited references toobservations of slugs of the genus Limax on flower heads inwet weather and thus serving as possible pollen vectors.

(b) Seed Production and Dispersal-Under optimal conditions, Salisbury (1942) recorded annual achene productionby an individual L vulgare plant of about 26000 achenes.In Europe, Salisbury (1942) observed that plants producedan average of 14 flower heads, but not all flower heads produced achenes. He reported between 1 and 15 inflorescencesper plant in meadows with 111 to 290 viable seeds formedper inflorescence and 2689 seeds per plant. Coulson et al.(2001) found a mean of 251 seeds per inflorescence. InDenmark, Dorph-Petersen (1925) recorded 1300 to 4000seeds per plant, with vigorous plants producing up to 26 000seeds. L vulgare may accumulate a large seed bank. both inthe soil and on the soil surface. Parsons (1973) calculatedthat, in Australia. a pasture infested by L vulgare could produce 10 710 seeds m-2 (= 107.1 million ha-I). In the UnitedKingdom, Howarth and Williams (1968) reported that 1000achenes weighed 0.38 ± 0.16 SD g. Grime et al. (1988)reported a mean seed weight of 0.33 mg.

Achene maturation occurs within 10 days after flowersopen. Achenes are not generally dispersed far from the parent plant. In a study of equally spaced plants, up to 100seedlings established in the vicinity of 2-yr-old parent plants,largely in a downwind position (King andCole, unpublisheddata). Coulson et al. (2001) found that few seeds dispersedmore than 0.6 m from the parent plant. Dispersal distancewas not affected by mowing or sheep grazing treatments. Noseeds were found in dung of sheep that had grazed in plotscontaining L vulgare (Coulson et al. 2(01). Mature plantsmay retain many seeds on the plant (Grime et al. 1988), butfew seeds are retained over winter (Cole, pers. obs.).Considerable dispersal occurs through movement of haycontaining fruiting plants (Mitich 2000) or grass seeds(Salisbury 1961). Furthermore, the achenes are capable ofremaining viable after passing through the digestive tracts offarm animals, thus leading to further spread through uncomposted stable refuse (Georgia 1942; Salisbury 1961; Mitich2000). Up to 40% of the seeds passing through cattle remainviable (Howarth and Williams 1968), and viable seeds havebeen found in horse manure (Salisbury 1961). Dore andRaymond (1942) found viable seeds in cow manure in southern Quebec. They estimated a transportation rate of 300seeds per cow per season. Livestock and other animals alsomay transport seeds in their fleeces or coats (Georgia 1942).However Fischer et al. (1996) found very few L vulgareseeds carried on sheep's fleeces in Germany.

(c) Seed Banks, Seed Viability and Germination-L vulgareseeds can remain viable for an extended period if conditionsare not conducive to germination. Toole and Brown (1946)reported the results of a buried seed experiment in Virginia.Seeds were buried at 3 depths (20, 56 and 107 cm) in 1902and germination was tested in subsequent years.

Germination percentages remained high up until 10 yr when39, 29 and 41 % germination of seeds germinated from thethree respective depths. The next two trials, at 16 and 21 yr,showed a decline in germination percentages by about half.Trials after 21 yr showed a dramatic reduction althoughsome seeds (1 %) were still viable at the end of the experiment 39 yr after burial. Dore and Raymond (1942) estimated an average of 0.52 million viable seeds ha-1 in the surfacesoils of permanent pastures in southern Quebec. In theUnited Kingdon, Milton (1943) recorded seed populationsas high as 6.6 million ha-1 in the top 18 cm of soil.

Disk and ray achenes are similar in terms of size, massand general morphology, and germination tests on achenesfrom both sources at 20°C produced 9~95% germinationafter 4 d (Howarth and Williams 1968). The remainingseeds appeared to be dormant, and germinated after a muchlonger period. Although the ripening of L vulgare seeds isnot automatically followed by a period of dormancy, environmental conditions can sometimes induce seed dormancy(Howarth and Williams 1968).

Seeds may germinate as soon as they are shed becausethey have no innate dormancy mechanism (Povilaitis 1956).If conditions are conducive, most seeds germinate in the fallof the year in which they are shed or in the following spring(Salisbury 1961). Thompson (1989) showed that germination of L vulgare was inhibited in darkness but showed noresponse to differences in light intensity. Povilaitis (1956)recorded that germination in darkness was generally low butwas much higher at 20°C than at 30°C. A "prolonged" stratification (moist seeds at 1 to 7°C) reduced the sensitivity tolight and the seeds were able to germinate "to a reasonableextent" in the dark. Keller and Kollmann (1999) tested germination response in seeds collected from four Europeansites and found that germination percentage wa~ highbetween 5°C and 10°C with no further increase at highertemperatures. Geographic origin significantly affected germination response to temperature and day length. Rapid germination at relatively cool temperatures may be an adaptiveadvantage enabling seedlings to establish in a pasture situation where competitive shading may quickly develop.

When seeds were broadcast seeded and then lightly incorporated into fallow land, seedling establishment was only5% from a seed lot that produced 75% germination in thelaboratory (Cole and King, pers. obs.).

(d) Vegetative reproduction-Individual plants slowlyspread laterally by rooting along the decumbent portions ofthe stem and lowest branches. The lower decumbent portionof the stem overwinters and expands to form a rootstock orshort rhizome at or just below the soil surface. In followingyears, the rhizome expands and gives rise to roots and lateral as well as terminal stems. In dense populations, clumpswill coalesce as they expand. Excised branches rooted successfully in a commercial soil mix in the greenhouse (Coleand King, unpublished data).

9. HybridsAlthough Howarth and Williams (1968) indicated that nospontaneous L. vu/gare hybrids were confirmed in 1968,

eLEMENTS ET AL - LEUCANTHEMUM VULGARE LAM. 355

Hornback (1982) described Shasta daisy as a "complexhybrid" developed from Luther Burbank's artificial crossingof L vulgare with the Portuguese daisy L. maximum, theEuropean daisy L lacustre and the Japanese daisy L nipponicum. By listing Shasta daisy as L x superbum, HortusThird (L. H. Bailey Hortorium 1976) acknowledged it as ahybrid species.

The anomaly of discoid heads found infrequently in Lvulgare was described as an inheritable trait rather thanhybridization between normal radiate and mutant discoidheads as found in Bidens, Layia or Senecio (BogIe 1983).

10. Population DynamicsL vulgare is adapted to take advantage of disturbance andremoval of existing vegetation in pastures, rangeland, hayfields, abandoned croplands, roadsides, railway embankments and waste areas. A typical cycle, as observed inAlberta (Cole and King, pers. obs.), is as follows. The cyclebegins with disturbance and overgrazing, which allows Lvulgare to become established in a pasture. The plants produce large numbers of seeds, and if tillage is used, densestands of L vulgare may develop. Often these L. vulgarepopulations eventually succumb to competition by grassesand other species, but a substantial seed bank of L. vulgaremay remain in the soil, so that if disturbance and overgrazing recur, above-ground populations of L. vulgare wouldagain increase.

Testing the invasiveness of weeds in a Festuca ovina L.dominated grassland in the United Kingdom, Burke andGrime (1996) found that disturbance of the indigenous F.ovina sward was an important factor in the establishment ofL vulgaris from sown seeds. The small-seeded L vulgareproved more dependent on disturbance for establishmentthan some of the larger-seeded invaders sown. Olson andWallander (1999) noted that bare soil was more prominentin areas with high densities of L vulgare. Sanders (1993)found that, in general, L vulgare is more prolific on poorersoils. This may not necessarily indicate a preference for or atolerance of soils with low fertility, but more likely a competitive disadvantage on fertile soils (Olson and Wallander1999). Grime et al. (1988) indicated that L vulgare is morecommon in open habitats where the growth of potentialdominants is restricted by soil infertility and disturbance,such as cutting for hay and grazing. Olson et al. (1997) andSmith (1980) suggested that L. vulgare requires selectivegrazing of neighboring plants or a disturbance to establish.Once established, L. vulgare gains an advantage over moredesirable forage plants in pastures because it is seldomgrazed (Gilkey 1957). Howarth and Williams (1968) notedthat it was not abundant on lightly grazed grasslands in theBritish Isles.

Under favourable germination conditions and the absenceof strong competitors, L vulgare can produce dense standsof seedlings. The combination of prolific seed production byestablished plants and good conditions can result in a densemat of rosettes (Olson and Wallander 1999). In Alberta,Cole et al. (1999) recorded an average population of 459seedlings m-2 in the spring after rototilling a L. vulgareinfested pasture the previous summer. Similarly, in the

northeastern United States. L vulgare became the dominantplant in a field after herbicides killed the existing plants andthe field was plowed and disked (Marks and Mohler 1985).

L vulgare can remain a dominant species in the plantcommunity and exhibit "white as snow" fields for a numberof years if the other vegetation does not grow to out-eompete the daisies or is removed by grazing or mowing (Fig.5). In western Canada, in the first year of growth from seedthe plant forms a vegetative rosette, with only about 1% ofthe rosettes producing flowering stems, flower heads andviable seeds. Flowers and seeds are generally produced inthe second and subsequent years (Cole 1998). As mentionedpreviously, population densities may increase noticeablywhere cattle are grazing because they selectively avoid Lvulgare (Mitich 2(00).

If other vegetation grows and shades L. vulgare, itbecomes less dominant in the plant community. In newlyestablished swards, L vulgare had an average biomass of2.5 g per plant 1 yr after seeding when growing with meadow bromegrass, compared to 21 grams per plant when growing with Kentucky bluegrass and 80 g per plant whengrowing alone on bare soil (Cole 1998). Cole (1998) foundthat using a vigorous forage species and/or fertilizer application to stimulate forage growth was an effective means ofsuppressing L. vulgare. The suppression was mainly a resultof reduced light reaching the L vulgare located lower in thecanopy. Boutin and Morisset (1988, 1989) reported that Lvulgare growth and leaf survival was considerably reducedwhen light and nutrition levels were reduced by 70%, withplants showing less response to variations in soil fertility.Maintaining an adequate plant canopy of associated speciesensures their competitiveness and minimizes light penetration to the seedlings. rosettes and basal leaves of floweringL. vulgare in lower canopy levels (Olson and Wallander1999). A thick litter layer also impedes germination andestablishment of L vulgare (Povilaitis 1956).

Using microscale field mapping on reseeded formerarable land in the United Kingdom, Spearman et al. (2000)found L. vulgare to have clumped patterns of distributionwith little or no association between seedling "clumps" andmature plant "clumps". In general, both seedling and matureplant densities declined over the growing season and overyears, although not declining to extinction within clumps,suggesting that L. vulgare persists preferentially in patchesof suitable habitat. The fact that the density, dispersion andpersistence of L vulgare varied among sites seeded with different ecotypes may indicate a difference in ecotype success(Spearman et al. 2000). Rich and Woodruff (1996) reporteda significant decrease in the frequency of L. vulgare from1930 to 1960 in unimproved grassland in Scotland.However, there is potential for future population growthfrom buried seed reserves. L vulgare seeds in the soil canremain viable for many years (Section 8c) to germinate andre-invade the plant community when conditions becomefavorable for growth. This may occur when the land is rotated back into slow-to-establish forage species. Livingstonand Allessio (1968) found that in Massachusetts ox-eyedaisy invaded fields quickly after their abandonment andpersisted for about 2 yr. Viable seeds were recorded in the


soils of these fields for up to seven additional years. Princeand Hodgdon (1946) observed viable ox-eye daisy seedsburied in old pasture soils of New Hampshire. Although oxeye daisy was a common weed in the study area, they foundgermination rates of interred seeds to be very low. Asdetailed in Section 8c, Toole and Brown (1946) reportedsome viable seeds at the end of the Duvel experiment inVirginia, 39 yr after burial.

Rodent burrows in pastures and hay fields can also createareas where L vulgare seeds are exposed to mineral soil andminimal competition (Olson and Wallander 1999).

11. Response to Herbicides and Other ChemicalsExperimental results in Alberta indicated that L vulgaresprayed with herbicides in May (Cole et al. 1994) did notexhibit new stem growth from the base of the plant, as wasobserved in plants sprayed in June (Maurice and Cole 1987). InMay, when L vulgare was mostly 3 cm in height and 20% ofthe plants were in the early bud stage, spraying metsulfuron (18g ai. ha-I) , metsulfuron (18 g ai. ha- ) +2,4-D ester (0.56 kga.i. ha-I) and pic10ram (0.54 kg a.i. ha-I) provided almost complete control in the year of application at three different experimental sites in central Alberta (Cole et al. 1999). Dichlorprop(1.20 kg a.i. ha-I) + 2,4-D ester (1.13 kg a.i. ha-I), 2,4-D amine(1.68 kg a.i. ha-I), 2,4-D ester (1.68 kg a.i. ha-I), dicamba (1.0kg a.i. ha-I) + 2,4-D ester (1.0 kg a.i. ha-I), thifensulfuron (0.04kg a.i. ha-I) + tribenuron (0.02 kg a.i. ha-I), c10pyralid (0.20 kga.i. ha-I), c10pyralid (0.20 kg a.i. ha-I) + 2,4-D ester (0.56 kga.i. ha-I), and mecoprop (0.26 kg a.i. ha-I) + dicamba (0.35 kga.i. ha-I) + 2,4-D amine (0.95 kg a.i. ha-I) all provided intermediate control. Triclopyr at 0.96 kg a.i. ha-I, MCPA at 1.68kg ai. ha-I and 2,4-DB at 1.68 kg ai. ha-I did not control Lvulgare. Coiteux and Cartier (1957) reported that two applications of 2,4-D amine at 1.12 kg ai. ha-I, one in the spring andanother one in the fall, were needed to "assure good control" ofL vulgare at L'Assomption, Quebec.

In western US rangelands, Olson and Wallander (1999)reported that herbicides, such as 2,4-D (2.24 kg a.i. ha-I)and picloram (0.14 kg a.i. ha-I), may control L vulgare inpastures for 2 to 3 yr, but herbicides have to be reappliedevery 3 to 5 yr to prevent new plants from establishing fromseeds in the seed bank. They also stated that herbicides mayharm native perennial forbs and may not be cost-effective inmany areas. In another study, Olson and Wallander (1999)reported that picloram (0.42 kg a.i. ha-I) tank- mixed with2,4-D (1.10 kg a.i. ha-I) provided 100% control of L. vulgare for 2 yr on a mountain pasture in southwesternMontana. This treatment, however, was not recommendedfor long-term control.

In lawns in Virginia, control was better with mecoprop +2,4-D than with dichlorprop + 2,4-D (Bingham et al. 1986).In a similar setting, metolachlor (4.5 and 9.0 kg a.i. ha-I) didnot reduce stands or flowering of L vulgare, but combiningsimazine or isoxaben with metolachlor resulted in significant injury and stand reduction of L vulgare (Derr 1993).

In parts of the United Kingdom, L. vulgare has beenreported to be fully resistant to 2,4-DB and MCPB, moderately resistant to 2,4-D, MCPA and mecoprop and susceptible to a very high rate of 2,4-D (5.6 kg a.i. ha-I) (Howarth

and Williams 1968). MCPA and 2,4-D at 2.24 kg a.i. ha-I

stopped the growth ofL vulgare at a site in Europe and prevented flowering (Salisbury 1961). Isoxaben (0.63 and 1.25kg a.i. ha-I) virtually eliminated L vulgare from artificialseed banks in the United Kingdom. (Pywell et al. 1998).

Likewise, resistance to 2,4-D and also MCPA has beenreported In New Zealand (Taylor 1981). Martin et al. (1990)reported poor control by either metsulfuron or picloram +2,4-D when applied using a rotary weed wiper, althoughmetsulfuron was the "more active" of the two. However,Sanders and Rahman (1994) reported effective control of Lvulgare obtained through spring applications with thifensulfuron (15 and 30 g a.i. ha-I), 2,4-D (2.07 kg a.i. ha-I) and2,4-D (2.07 kg a.i. ha-I) + clopyralid (30 g a.i. ha-I) in NewZealand. Nicholson et al. (1993) found fall or spring spraying with these same herbicides provided comparable controlin New Zealand. Fall spraying, however, caused more damage to Trifolium repens. All treatments delayed flowering ofL vulgare for 2 mo, with thifensulfuron controlling L. vulgare as well as 2,4-D + clopyralid but with significantly lessdamage to legumes. Also in New Zealand, Fellowes (1973)found that bentazon alone at 1.12,2.24 and 3.36 kg a.i. ha-Iand with MCPB at 1.12 kg a.i. ha-I substantially reduced theoccurrence of L vulgare without injuring Lolium perenneL. or T. repens.

Unfortunately, most of the herbicides that control L. vulgare also remove or suppress any legumes and other desirable broad-leaved plants growing in pasture, rangeland orhay land (Cole et al. 1999). A valuable component of theforage stand is removed and at the same time there is lesscompetition for the L. vulgare. In two field experiments incentral Alberta, the removal of the legume and broad-leavedpla~t comfonent of !he ~or~ge stand with metsulfuron at 18g a.l. ha- resulted m slgmficantly more L. vulgare plantsthe year after spraying than in the untreated control (Coleet al. 1999). The use of herbicides alone may not be the bestmethod of obtaining long-term management of L. vulgare,especially if legumes and other susceptible broad-leavedplants make up a significant proportion of the stand.

12. Response to Other Human ManipUlationsThree direct methods of non-chemical control of ox-eyedaisy are hand pulling, cultivation and mowing. These threemethods will be discussed below, followed by discussion offive general management strategies: grazing management,consideration of relative competitive ability, fertilizer application, fertilizers in conjunction with other factors, andadditional preventative strategies.

Hand pulling and removing new, small infestations offlowering plants will help prevent spread by seeds, but theentire rootstock can be difficult to remove from the ground(Cole et al. 1999).

Cultivation will control L. vulgare and Muenscher (1955)recommended a short rotation, including a cultivated crop atleast once every 3 yr. Cultivation is not always possible inmany pastures, rangelands and roadside areas (Olson andWallander 1999) and cultivation may also stimulate seedgermination. At an eastern US site, Marks and Mohler

.' t"


(1985) found L. vulgare to be the dominant plant species ina field 14 mo after being sprayed with herbicides, followedby plowing and disking to kill existing plants.

Georgia (1942) and Muenscher (1955) recommendedmowing infested meadows as soon as the first flowersappear, mainly to prevent the further production and spreadof seeds. Howarth and Williams (1968), however. reportedthat L vulgare abundance appears to be related to the cutting or grazing intensity and that it "resists" cutting.Although timely mowing will prevent or reduce L vulgareseed production, it may also increase L vulgare stand density by removing competitive forage growth, especially afterseveral mowings. Four mowing experiments in pasture andhay fields in central Alberta showed increased ox-eye daisynumbers with additional mowings (Cole et al. 1999). At onesite, the number of plants the year following different mowing regimes was 393 m-2 with three mowings, 350 plantsm-2 with two mowings, 235 plants m-2 after one mowingand 156 plants m-2 in the unmown control. The increase inplant numbers was mainly in flowering plants and notrosettes or seedlings. Olson and Wallander (1999) acknowledged that mowing may stimulate rosette production (andthus flowering plants the following year).

The direct non-chemical manipulations discussed abovehave had limited success. To address a L vulgare infestationin pasture, it is important to ensure that the pasture is notovergrazed (Holm et al. 1997), especially under dry conditions. In the United Kingdom, population increases weremuch smaller with intensive rotational grazing by cattle andintensive rotational and season-long grazing by sheep, whilelenient cattle grazing did not affect population levels(Norman 1957; Pilkington et al. 2(00). Olson et al. (1997)provided information that 2 yr of short-duration (5.5 to 9 dper season) intensive cattle grazing in the Northwestern USreduced L vulgare seedling and rosette densities with minimal impact on the grasses (Phleum pratense L., Bromusinermis Leyss., Poa pratensis L. and Dactylis glomerata L.)present in the pasture. After short- duration intensive grazing to trample and "force" cattle to eat L vulgare, a long restperiod allowed the forage to recover and become competitive with L vulgare (Olson and Wallander 1999). Olson andWallander (1999) also speculated that sheep and goatswould probably have a more significant impact on L vulgare than cattle, as sheep and goats readily graze it (01sonand Lacey 1994). By reducing seed production, they wouldreduce spread and, potentially, the competitiveness of thespecies. Grazing by cattle and other ungulates may alsospread L. vulgare seed via their feces (Howarth andWilliams 1968) as Olson and Wallander (1999) found thatcattle did not completely avoid the plant.

Pasture management may also involve planting competitive forages. Cole et al. (1999) seeded Phleum pratense,Bromus inermis, Bromus riparius (= biebersteinii Roem. &Schult.), Dactylis glomerata, Festuca rubra L., Poa pratensis, Medicago sativa L., Trifolium hybridum L. andHordeum vulgare L. into pasture heavily infested by L. vulgare that was rototilled to stimulate germination of L vulgare seeds. In the newly established sward, L vulgare hadan average biomass of 124 g m-I I yr after seeding when

growing with P. pratense (similar biomass when growingwith the other perennial grasses) compared to 34 g m-Iwhen growing with T. hybridum, 13 g m-I when growingwith M. sativa and 0.2 g m-I when growing with H. vulgare.When establishing a forage stand in a field infested by Lvulgare seeds, a suitable legume component may aid thenew stand in outcompeting the L vulgare in a shorter time,but would limit herbicide options as compared to establishing a grass-only forage stand. Using tillage and an annualcrop such as H. vulgare may reduce L vulgare but a sizeable seed bank might still be present.

L vulgare may be managed quite effectively by fertilizerapplications. L vulgare was outcompeted by the sown forage species when fertilizer was spring-applied to hay landfor 2 consecutive years at four different experimental sitesin central Alberta (Cole et al. 1999). At one site, L vulgarewas reduced from 218 plants m-2 to 0 plants m-2 within 2yr. The application of fertilizer at soil-test recommendationrates in the early spring over several years, maintained suppression of existing plants and prevented the establishmentof new plants from seed. Annual fertilizer applicationappeared to be particularly important in years of high moisture levels since the increased moisture resulted in a largerresponse by the forage species to fertilizer application.Olson and Wallander (1999) reported that fertilizer application alone over several years was almost as effective atreducing growth as applying the herbicides, 2,4-D (2.24 kga.i. ha-I) and picloram (0.14 kg a.i. ha-I) in a trial conducted in eastern Washington. Ninety kg ha-I of N was the mostcost-effective treatment after 7 yr, with grass yields increasing by 500% in higher-level N treatments. Maintaining anadequate plant canopy ensures a competitive stand that minimizes light penetration to seedlings and rosettes of L vu!gare (Olson and Wallander 1999).

Greenhouse studies demonstrated that under low lightconditions, L vulgare' was unable to respond to increasedlevels of soil nutrients (Cole 1998). When artificially shaded, L. vulgare biomass decreased linearly with decreasinglight intensity. An 85% reduction in light intensity reducedrosette biomass by 70% and seedling biomass by 92%. Anintegrated approach with an effective herbicide and fertilizer applied at lOO kg N ha-I and P, K and S to soil test recommendations as a surface application in April or May,increased the level of control compared with either treatment alone (Cole et al. 1999). In grass-only stands, herbicide and fertilizer treatments complemented each othermore than in grass-legume stands. Similarly, Olson andWallander (1999) reported considerable success at managing L vulgare with herbicides and fertilizers, as the herbicide provided at least top-growth control of the plant, whilethe fertilizer stimulated growth of accompanying grasses.Fertilizer application and sheep or goat grazing may also beconsidered for an integrated-management approach to control, as long as the animals preferentially graze L. vulgareover the forage species (Olson and Wallander 1999).

Preventative measures can be used to avert new L vulgareinfestations by limiting intentional and unintentional spread ofseeds (OOOn and Wallander 1999). Public awareness, prohibiting L vulgare in wild-flower seed mixes, checking crop seed


certificates for weed seed content. hay-certification programs,restricting livestock movement after they have been in L vulgare-infested pastures (Georgia 1942) and sanitizing harvesting, tillage and other equipment before moving any of it touninfested areas are measures that can be used to help preventthe spread of this weed. In the United States, L vulgare seedsare an impurity of nearly all grass-seed commodities and fruiting plants are often cut with hay, baled and shipped widelythroughout the country (Forcella 1985; Mitich 2000).

13. Response to Herblvory, Disease and HigherPlant ParasitesHerbivory(a) Mammals-Some ungulates, such as goats, horses andsheep feed on L. vulgare, but others, such as cattle and pigs,avoid it (Howarth and Williams 1968; Olson 1999; Olsonand Wallander 1999). Clear-Hill and Silvertown (1997)found that winter grazing by sheep reduced L. vulgareseedling emergence in the United Kingdom. In Montana, 2yr of intensive grazing by cattle reduced densities of L. vulgare seedlings and rosettes and the number of seeds in thesoil seed bank, but did not change densities of mature stems.Much of the impact of cattle was due to trampling andremoving stems rather than to actual grazing.

(a) Birds-No information found.

(c) Insects-Relatively few insects have been recorded feeding on L vulgare in North America. These include the aphidsMacrosiphoniella leucanthemi Ferrari and Macrosiphoniellasanbomi (Gillette) (Miller and Stoetzel 1997; Stoetzel andMiller 1999) and the lygus bug, Lygus rubrosignatus Knight(Schwartz and Foottit 1992). L vulgare contains acetylenesand thiophenes, which induce phototoxicity against phytophagous insects, although insects such as the lepidopteranArgyrotaenia velutinana Walker have been observed feedingon L vulgare in Canada, through behavioral strategies thatavoid direct sunlight (Guillet et al. 1995). Insects recorded asfeeding on L vulgare in Europe are much more numerous,and include the beetles Apion detritum Rey, Apion stolidumGermar, Cryptocephalus bilineatus (L.), Mantura chrysanthemi Koch, Coryssomerus capucinus Rossi, Cyphocleonustrisulcatus Herbst, and Microplontus campestris (Gyllenhal);the flies Chromatomyia ciliata (Hendel), Chromatomyiaparaciliata Godfray, Melanagromyza eupatorii Spencer,Phytomyza leucanthemi Hering, Oxyna nebulosaWiedemann, Tephritis neesii Meigen, Trypeta artemisiae L.;the gall midges Clinorrhyncha leucanthemi Kieffer,Contarinia chrysanthemi Kieffer, Dasyneura chrysanthemiBarnes, and Rhopalomyia hypogaea F. Loew; the aphidsMacrosiphoniella trimaculata Hille Ris Lambers andToxopterina vandergooti C. B.; the psyllid Craspedoleptajlavipennis Forster; and the moths Bucculatrix nigricomellaZeller, Coleophora gardesanella Toll, Coleophora trochilella Duponchel, Hellinsia lienigianus Zeller, Homoeosomanebulella Denis & Schiffermtiller, Aethes margaritanaHaworth, Cnephasia asseclana Denis & Schiffermtiller.Cnephasia conspersana Htibner, Cnephasia genitalanaPierce & Metcalfe, Cnephasia incertana Treitschke.

Cnephasia interjectana Haworth. Cnephasia longanaHaworth, Cnephasia pasiuana Hilbner, Cnephasia stephensiana Doubleday, Cochylidia implicitana Wocke,Dichrorampha acuminatana Zeller. Dichrorampha aeratanaPierce & Metcalfe, Dichrorampha alpinana Treitschke,Dichrorampha consortana Stephens. Dichroramphaplumbana Scopoli, and Eana incana Stephens (Bames et al.1962; Scherf 1964; Freude et al. 1966; Howarth and Williarns1968; Bradley et al. 1973; Janzon 1980; Davis et al. 1982;Godfray 1985; Groppe 1988; White 1988; Spencer 1990;Heath 1991; Gielis 1996; Greve 1999; Peat and Fitter 2(01).Some of these species may be host-specific enough to havepotential as biological control agents.

(d) Other invertebrates--Ox-eye daisy was observed to supportmoderate populations of the northern root-knot nematodeMeloidogyne hapla Chitwood in Quebec (Belair and Benoit1996) and Ontario (Townshend and Davidson 1962).Townshend and Davidson (1960), surveying plants aroundareas of strawberry cultivation affected with root rot in southern Ontario, found that the nematode Pratylenchus penetrans(Cobb) Chitwood & Otiefa formed orange to brown lesions inthe roots of ox-eye daisy. The low infection rates observedwere attributed to the unfavourable hardness of ox-eye daisyroots. Mauch and Ferraz (1996) found that L vulgare supported high levels of reproduction of the southern root knot nematode Meloidogyne incognita (Kotoid & White) Chitwood race3 in Brazil. Although it cannot endure freezing soil temperatures, M. incognita did attack ox-eye daisy in the greenhouseexperiments of Davidson and Townshend (1967). Both speciesof Meloidogyne form root galls on many species of plants.Howarth and Williams (1968) mention Aphelenchoides fragariae Christie, A. ritzemabosi Schwartz, and Ditylenchus dipsaci (Kun) Filipjev, as feeding on L vulgare.

The slugs Deroceras reticulatum Muller and Arion lusitanicus Mabille feed on L vulgare in Switzerland (Keller et al.1999). Clear-Hill and Silvertown (1997) observed thatD. reticulatum reduced seedling emergence ofL vulgare in the UnitedKingdom. The gall mite Epitrimerus alinae Liro has beenrecorded feeding on L vulgare in Finland (Davis et al. 1982).

Diseases(a) Fungi-Fungi reported on ox-eye daisy in Canadainclude Ceratobasidium anceps (Bres. & Syd.) Jackson(Conners 1967) and Ophiobolus mathieui (Westend.) Sacc.(Ginns 1986). The following fungi were recorded as associated with L. vulgare in Europe: Deuteromycetes Septoriacercosporoides, S. chrysanthemi Allescher, S. leucanthemiSacc. Speg. (Br. Rust F.), S. socia Pass.; AscomycetesProtomycopsis leucanthemi Magnus; and BasidiomycetesPuccinia leucanthemi Pass, Botrytis cinerea Fr., Oidiumchrysanthemi Rabenh., and Verticillium alboatrum Reinke& Berth. (Howarth and Williams 1968). The fungiPeronospora radii de Bary, Puccinia cnici-oleracei Pers.ex Desm., Septoria chrysanthemi Allescher" Septoria leucanthemi Sacc. & Speg. and Septoria socia Pass. werereported on L. vulgare by ElIis and ElIis (1985).Phytophthora tentaculata Krober and Marwitz wasdescribed from L. vulgare plants affected by a root and

......

CLEMENTS ET AL. - LEUCANTHEAfUAf VULGARE LAM. 359

stem base rot in greenhouses in Germany (Krober andMarwitz 1993)(b) Bacteria-Howarth and Williams (1968) listCorynebacteriumfascians (Tiff.) Dowson as parasitic on L.vulgare. Erwinia chrysanthemi pv. chrysanthemi causes abacterial blight on related chrysanthemums including L.maximum (Burkholder et al. 1953), and is also reported fromL. vulgare (Instituto Colombiano Agropecuario 2(02). Theaphid-vectored aster yellows phytoplasma (previously considered a virus) was reported on L. vulgare in P.EJ.(Conners and Savile 1944). It has also been reported on L.vulgare in Italy (as the Italian clover phyllody), causing yellowing, virescence, and phyllody (Firrao et al. 1996).

(c) Viruses-Potato yellow dwarf virus was reported on L.vulgare in North America (Youngkin 1942). Tomato spotted wilt virus (Howartb and Williams 1968; Oliveira andKitajima 1989; Ruter and Gitaitis 1993) is known to infectL. vulgare throughout the world, including North America,South America and Europe.

ACKNOWLEDGEMENTSWe wish to thank Roy Cranston and the late Larry Mitichfor their help regarding reference material. We gratefullyacknowledge the work of Tonya Snidal and ChristopherBuschhaus for producing the distribution map and editingthe MS. We thank Trinity Western University for a grant tohelp with publication costs. We also acknowledge the generous assistance of the herbarium curators who suppliedinfonnation for the distribution map. Figure 1 was illustrated by Regina O. Hughes (Anonymous 1970).

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