Crataegus monogyna
(hawthorn)

Pictures

Picture	Title	Caption	Copyright
Title Tree habit Caption Typical shrubby specimen of hawthorn on the edge of the valley of the River Warta in Poznan, Poland. Spring 1999. Copyright Wojciech Stachnowicz	Tree habit	Typical shrubby specimen of hawthorn on the edge of the valley of the River Warta in Poznan, Poland. Spring 1999.	Wojciech Stachnowicz
Title Flowers Caption A blossoming twig, with leaves, of hawthorn. Valley of the river Warta in Poznan, Poland. Spring 1999. Copyright Wojciech Stachnowicz	Flowers	A blossoming twig, with leaves, of hawthorn. Valley of the river Warta in Poznan, Poland. Spring 1999.	Wojciech Stachnowicz

Identity

Preferred Scientific Name

• Crataegus monogyna Jacq.

Preferred Common Name

• hawthorn

Other Scientific Names

• Crataegus aegeica Pojark
• Crataegus alutacea Klokov
• Crataegus azarella Griseb.
• Crataegus boissieri Willk.
• Crataegus brevispina Kunze
• Crataegus calycina Peterm. subsp. calycina
• Crataegus calycina Peterm. subsp. curvisepala (Lindm.) Franco
• Crataegus ceratocarpa Kossych
• Crataegus granatensis Boiss.
• Crataegus laciniata sensu Willk., non Ucria
• Crataegus lasiocarpa Lange
• Crataegus leiomonogyna Klokov
• Crataegus lipskyi Klokov
• Crataegus maura auct. hisp., non L.f.
• Crataegus oxyacantha L., nom. ambig.
• Crataegus oxyacantha L., nom. ambig. subsp. oxyacantha
• Crataegus oxyacantha var. praecox hort. ex Loudon
• Crataegus panachaica C.K.Schneid.
• Crataegus popovii Chrshan.
• Crataegus praearmata Klokov
• Crataegus transalpina A.Kern.
• Crataegus triloba auct., non (Poir.) Pers
• Mespilus monogyna (Jacq.) All.
• Mespilus oxyacantha (L.) Crantz

International Common Names

• English: European hawthorn; May tree; May-tree; oneseed hawthorn; one-seeded hawthorn; single-seed hawthorn; whitethorn
• Spanish: espino albar
• French: aubépine a un style; aubépine monogyne
• Russian: boyaryshnik odnopestnyi
• Portuguese: pirliteiro

Local Common Names

• Czechoslovakia (former): hloh jednosemenny
• Germany: Eingriffeliger Weissdorn; Eingriffliger Weissdorn; Saulenweissdorn
• Italy: biancospino; cratego monogino
• Netherlands: eenstijlige Meidoorn
• Poland: glog jednoszyjkowy
• Sweden: trubbhagtorn
• UK: common hawthorn; single-seed hawthorn
• USA: European hawthorn; singleseed hawthorn

EPPO code

• CSCMO (Crataegus monogyna)

Summary of Invasiveness

C. monogyna is the common hawthorn native to most of Europe, North Africa and West Asia. This thorny bush or small tree was introduced to North America and Australasia in the 1800s, naturalizing but only in more recent years becoming an environmental weed, especially on the Pacific coast of North America and parts of Australia and New Zealand. Seed are widely dispersed by birds who prefer the fruit over that from native plants, and thickets can form that suppress native vegetation especially in natural forest but also many other habitats. It is also hybridizing with native Crataegus species in invaded areas. Further invasion and spread of this species is to be expected especially in North America, and further introduction should be prevented.

Taxonomic Tree

• Domain: Eukaryota
•     Kingdom: Plantae
•         Phylum: Spermatophyta
•             Subphylum: Angiospermae
•                 Class: Dicotyledonae
•                     Order: Rosales
•                         Family: Rosaceae
•                             Genus: Crataegus
•                                 Species: Crataegus monogyna

Notes on Taxonomy and Nomenclature

The genus Crataegus, part of the Rosaceae family (subfamily Maloideae), contains over 200 species, though some taxonomists divide these further and they may be over 1000 species depending on the descriptions followed. Several varieties and forms have been proposed, and European species are described and defined by Christensen and Janjic (2006). A number of subspecies are also recorded: subsp. monogyna (Royal Botanic Garden Edinburgh, 2007) from France to southern Ukraine, subsp. aegeica (Pojark.) Franco in the eastern Aegean, subsp. azarella (Griseb.) Franco in southeastern Europe (southern and eastern Spain and Italy, also Sicily), subsp. brevispina (Kunze) Franco in Portugal, Spain and the Balearic islands, subsp. leiomonogyna (Klokov) Franco in Russia, and subsp. calycina (Peterm.) Soó and subsp. intermedia (Fuss) Jáv. (ranges not stated).

Crataegus spp. are commonly known as the hawthorns, though species-specific vernacular names may be applied to several species, such as English hawthorn and white thorn being applied to both Crataegus monogyna and Crataegus laevigata. It is also not impossible that some introduced populations will in future be attributed to C. laevigata and not C. monogyna, and also that new spontaneous hybrids will develop in introduced ranges with both exotic and native Crataegus species as parents. The ‘haw’ in hawthorn is the name of the fruit. Many species are able to freely hybridize, further increasing variability and speciation. Being a valued ornamental, horticultural selections have also been made, and there exist a large number of cultivars.

Description

C. monogyna is a thorny shrub or small tree up to 10 m high though commonly 2-6 m, with smooth pale grey bark. Branches straight with stout spines on branches; leaves alternate, ovate to obovate, 1.5-3.5 cm long, 3-7-lobed, margins entire or sparingly serrate, mostly glabrous except for patches of hairs in axils of veins on the underside. Flowers white fading to pink, in clusters, petals 5, styles 1. Fruit single-seed red berries, 1.25 cm in diameter.

Plant Type

Distribution

C. monogyna is widely distributed (Meusel et al., 1965), native to most of Europe excluding its northeastern part, and to parts of the Mediterranean coast of North Africa. C. monogyna is generally regarded as lowland species, however it has been reported from Cyprus at 1525 m in altitude, Albania and Lebanon (1600 m), Macedonia (1630 m), Greece (1650 m) and Anatolia (up to 2200 m in altitude).

Distribution Table

The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

History of Introduction and Spread

It has been widely introduced, is commonly planted and has become naturalized in North America, southern Africa, Australia and New Zealand having been introduced to each sometime in the 1800s. It has been observed to be an aggressive colonizer (Bass, 1990; Williams et al., 1986), and has become an invasive species in the Pacific northwest of the USA (Oregon and Washington), also British Columbia, and it was recently noted as fully naturalized and a potential pest in northern California, USA (Hrusa et al., 2002). It is also one of six woody invasive species in New York, USA, by Hunter and Mattice (2002), and noting its widespread distribution in North America (USDA-NRCS, 2007), further invasion in other states and provinces is highly likely. C. monogynais also invasive in South Africa, where birds are aiding spread in the Eastern Cape (Reichard et al., 2001). It is very invasive in northern New South Wales, having spread rapidly and conspicuously throughout the region and elsewhere in southern Australia at rates of 80–120 m yr^-1 (Bass et al., 2006), and it is an environmental weed of concern in New Zealand, having been introduced in 1899 (Owen, 1996).

Risk of Introduction

It is a noted weed in all countries where it is spreading. It is on California’s CalEPPC Red Alert list, and is expected to be declared noxious in other states and countries. Existing stands should be monitored, and further introduction via the horticultural trade should be prevented.

Habitat

C. monogyna is found in lowland areas on many soils, and is often considered principally a forest understory species in its native range, though it also prefers moist to damp disturbed places such as wetlands and lake margins as well as and open forests. It appears to thrive best in deeper soils. Throughout its range C. monogyna grows in several types of open forests and thickets, and in Central Europe, it forms its own plant community Pruno-Crataegetum, being a successional stage of vegetation leading to natural oak-hornbeam forests (Querco-Carpinetum sensu lato) (Wojterska, 1990).

In North America, riparian areas, abandoned fields and pastures, oak woodlands, and other forested habitats must be considered as potential habitat although outlying plants can be found in shrubland or grassland, especially near the coast (Alverson and Sigg, 2008).

Habitat List

Biology and Ecology

C. monogyna grows best in humid and sub-humid temperate zones, though is also native to cold climates in Scandinavia and is introduced in Canada and Alaska, USA. Once established, C. monogyna can withstand moderate drought.

Climate

Latitude/Altitude Ranges

Air Temperature

Rainfall

Rainfall Regime

Soil Tolerances

Soil drainage

• free

Soil reaction

• acid
• neutral

Soil texture

• heavy
• medium

Special soil tolerances

• infertile
• shallow

Notes on Natural Enemies

There are relatively few pests and pathogens of C. monogyna. The most important disease is ‘fire blight’ caused by the bacteria Erwinia amylovora, and it should never be planted in the neighbourhood of orchards as it acts as an alternative hosts for this, one of the most dangerous disease of fruit-trees of the family Rosaceae (Zajaczkowski, 1998). In Australia, plants are severely attacked by the pear and cherry slug (Caliroa cerasi) in some years, which damages the foliage though this does not appear to harm the tree itself.

Means of Movement and Dispersal

The principal means of long-distance dispersal has been its intentional introduction as an ornamental/landscaping and hedging/boundary plant. For these reasons, it was introduced to North America, South Africa and Australasia, and further introduction may be likely.

Pathway Causes

Pathway Vectors

Impact Summary

Economic Impact

There are clear positive impacts from the propagation and sale of C. monogyna and its many cultivars as ornamental plants, and also for the sale of seedlings or cuttings from commercial forestry nurseries for planting as hedges or in general landscaping. However, no exact data as to its economic contribution are forthcoming, and it may be expected that such exact figures would be difficult to estimate. Negative impacts are also increasing likely in the form of control programmes in natural areas of North America and Australasia where it is becoming a problematic invasive weed.

In addition, due it acting as a host for crop pests and pathogens or pests, it should not be planted near some crops, such as fruit trees and hops (Puszkar, 1981; Zajaczkowski, 1998).

Environmental Impact

Hawthorn's thickets are shelters for many birds and little mammals, therefore, they are important for nature protection purposes, especially on agricultural or urbanized grounds.

However, where invasive, it displaces native plants, and dense thickets alter the structure of the forest understory and can make the movement of large animals difficult. Some species of Crataegus contain hydrocyanic acid in the leaves, which is poisonous to cattle, though the presence of this in C. monogyna is not yet known. Birds may prefer its berries to those of native berried plants, which may cause a reduction in the regeneration of native plants. Also, the ability of C. monogyna to hybridise with native species of Crataegus, means that there will be genetic pollution of the indigenous gene pool over time in invaded areas.

One nature preserve in Willamette Valley, Oregon, USA, has had to be abandoned because C. monogyna has invaded and there are not adequate resources to control it (Alverson and Sigg, 2008), and there is also a specific threat to the Garry Oak ecosystem of British Columbia, Canada.

Risk and Impact Factors

• Proved invasive outside its native range
• Has a broad native range
• Abundant in its native range
• Highly adaptable to different environments
• Tolerates, or benefits from, cultivation, browsing pressure, mutilation, fire etc
• Pioneering in disturbed areas
• Highly mobile locally
• Long lived
• Has high reproductive potential
• Reproduces asexually
• Has high genetic variability

• Changed gene pool/ selective loss of genotypes
• Ecosystem change/ habitat alteration
• Modification of successional patterns
• Monoculture formation
• Reduced native biodiversity
• Threat to/ loss of endangered species
• Threat to/ loss of native species

• Competition - monopolizing resources
• Competition - shading
• Pest and disease transmission
• Hybridization
• Interaction with other invasive species
• Pollen swamping

• Highly likely to be transported internationally deliberately
• Difficult to identify/detect as a commodity contaminant
• Difficult to identify/detect in the field

Uses

C. monogyna is often planted in hedges and shelterbelts on farms and as an ornamental shrub or small tree in towns and cities and has been successfully used in revegetation and land reclamation of wastelands and mine spoils (Kluczynski, 1981; La Marca et al., 1998) as well as on polders in Holland (Peeters and Stuurman, 1981). The species is relatively tolerant to air pollution (Hirka, 1992) and as such seems to be particularly convenient for planting along roads and motorways. The spines deter grazing animals, and the plant is regarded as an impenetrable barrier to grazing. Seeds require stratification before sowing in spring, and 1-2-year-old seedlings or cuttings are used, the latter best in gaps within old hedges.

The wood of C. monogyna is narrow-ringed, extremely hard and durable and is sometimes used for the production of various small objects. The possibility of its utilisation for other purposes is limited by its low speed of growth. The flowers and fruits of hawthorn have been used in folk medicine for a long time and are now regarded as a precious raw material in production of important drugs to combat heart disease (e.g. Iwamoto et al., 1981), hypertension and allergies. The fruits of C. monogyna contain many vitamins, and are widely collected and consumed in some rural areas where native.

Uses List

Environmental

• Agroforestry
• Amenity
• Boundary, barrier or support
• Revegetation
• Shade and shelter
• Soil conservation
• Wildlife habitat
• Windbreak

Fuels

• Fuelwood

General

• Ornamental

Human food and beverage

• Emergency (famine) food
• Fruits
• Honey/honey flora

Materials

• Carved material
• Poisonous to mammals
• Wood/timber

Medicinal, pharmaceutical

• Source of medicine/pharmaceutical
• Traditional/folklore

Ornamental

• Propagation material

Wood Products

Woodware

• Tool handles
• Turnery
• Wood carvings

Similarities to Other Species/Conditions

Native Crataegus on the west coast of North America can be distinguished from the introduced C. monogyna as they generally have purple-black (not red) fruit, mostly unlobed (not lobed) leaves and 5 (not 1) styles. Hybrids also have purple-black fruits but have leaves and flowers with intermediate characters, such as partially lobed leaves and flowers with 2-3 styles.

Prevention and Control

Due to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authority should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used in a lawful manner, consistent with the product's label.

Larger plants can be cut to the ground and the stump treated with a 1:3 mixture of triclopyr (or glyphosate) and a light cooking oil as surfactant, and a 2-3% solution of triclopyr or glyphosate has been sprayed on the foliage for control, but this has not generally been reliable and is more likely to affect non-target species than are stump treatments (Alverson and Sigg, 2008).

References

Alverson E; Sigg J, 2008. Crataegus monogyna datasheet. Davis, USA: University of California. http://ucce.ucdavis.edu/datastore/detailreport.cfm?usernumber=37&surveynumber=182

Amaral Franco J do, 1968. Crataegus L. In: Flora Europaea. Cambridge, UK: Cambridge University Press, 2:73-77.

Baranec T, 1986. Biosystematic study of the genus Crataegus L. in Slovakia. [Biosystematicke studium rodu Crataegus L. na Slovensku.] Acta Dendrobiologica, No. 12, 119 pp.; 164 ref.

Bass DA, 1990. A comparative study of the invasiveness of two alien fleshy-fruiting woody plants on the Northern Tablelands of New South Wales. Proceedings of the 9th Australian Weeds Conference, 109-112

Bass DA; Crossman ND; Lawrie SL; Lethbridge MR, 2006. The importance of population growth, seed dispersal and habitat suitability in determining plant invasiveness. Euphytica, 148(1/2):97-109.

Browicz K, 1986. Chorology of Trees and Shrubs in South-West Asia and Adjacent Regions. vol. 5. Warszawa-Poznan, Poland: Polish Academy of Sciences, Institute of Dendrology.

CABI, 2005. Forestry Compendium. Wallingford, UK: CABI.

Christensen KI; Janjic N, 2006. Taxonomic notes on European taxa of Crataegus (Rosaceae). Nordic Journal of Botany, 24(2):143-147.

García-Castaño JL; Kollmann J; Jordano P, 2006. Spatial variation of post-dispersal seed removal by rodents in highland microhabitats of Spain and Switzerland. Seed Science Research, 16(3):213-222. http://journals.cambridge.org/download.php?file=%2FSSR%2FSSR16_03%2FS0960258506000237a.pdf&code=40dda3597bbd3a74e4a6c55bf429b91c

Gosler AG, 1990. Introgressive hybridization between Crataegus monogyna Jacq. and C. laevigata (Poiret) DC. in the Upper Thames Valley, England. Watsonia, 18(1):49-62; 16 ref.

Gosler AG; Kelly CK; Blakey JK, 1994. Phenotypic plasticity in leaf morphology of Crataegus monogyna (Rosaceae): an experimental study with taxonomic implications. Botanical Journal of the Linnean Society, 115(3):211-219; 13 ref.

Gostynska-Jakuszewska M, 1978. Studia nad systematyka, rozmieszczeniem i zmiennoscia glogów wystepujacych w Polsce. 1. [Studies on systematics, distribution and variability of hawthorns in Poland. Part 1.] Rocznik Sekcji Dendrendrologicznej, Polskie Towarzystwo Botaniczne, 31:5-20.

Gostynska-Jakuszewska M, 1979. Studia nad systematyka, rozmieszczeniem i zmiennoscia glogów wystepujacych w Polsce. 2. [Studies on systematics, distribution and variability of hawthorns in Poland. Part 2.] Rocznik Sekcji Dendrendrologicznej, Polskie Towarzystwo Botaniczne, 32:5-16.

Gostynska-Jakuszewska M, 1980. Studia nad systematyka, rozmieszczeniem i zmiennoscia glogów wystepujacych w Polsce. 3. [Studies on systematics, distribution and variability of hawthorns in Poland. Part 3.] Rocznik Sekcji Dendrendrologicznej, Polskie Towarzystwo Botaniczne, 33:53-63.

Gostynska-Jakuszewska M; Hrabetova-Uhrova A, 1983. Distribution of Crataegus species in Poland and Czechoslovakia. Preslia, 55(1):9-24.

Guitian J; Fuentes M, 1992. Reproductive biology of Crataegus monogyna in northwestern Spain. Acta Oecologica, 13(1):3-11

Hirka A, 1992. Effects of severe and direct industrial immissions on a Quercus cerris stand. [Uber Wirkungen starker und direkter Industrie-Immissionen auf einen Zerreichen-Bestand (Quercus cerris L.).] Anzeiger fur Schadlingskunde, Pflanzenschutz, Umweltschutz, 65: 151-153; 3 ref.

Hrusa F; Ertter B; Sanders A; Leppig G; Dean E, 2002. Catalogue of non-native vascular plants occurring spontaneously in California beyond those addressed in The Jepson Manual - Part I. Madroño, 49(2):61-98.

Hunter JC; Mattice JA, 2002. The spread of woody exotics into the forests of a northeastern landscape, 1938-1999. Journal of the Torrey Botanical Society, 129(3):220-227.

Ilmurzynski E, 1969. Szczególowa hodowla lasu. [Silviculture in detail]. PWRiL, Warszawa.

Iwamoto M; Ishizaki T; Sato T, 1981. Clinical effects of Crataegutt on heart diseases of ischaemic and/or hypertensive origin. A multi-centre double-blind study. [Klinische Wirkung von Crataegutt bei Herzerkrankungen ischamischer und/oder hypertensiver Genese. Eine multizentrische Doppelblindstudie.] Planta Medica, 42(1):1-16.

Kluczynski B, 1981. Studies of the suitability of trees and shrubs for the revegetation of siderite mine spoils in the Czestochowa region. [Badanie przydatnosci drzew i krzewow do rekultywacji i zagospodarowania hald posyderytowych w rejonie Czestochowy.] Arboretum Kornickie, 26: 203-229.

Kobendza R, 1955. Crataegus L. Glóg. In: Szafer W, Pawlowski B, eds. Flora Polska. Rosliny naczyniowe Polski i ziem osciennych. [The Polish Flora. Vascular Plants of Poland and neighbouring territories.] Warszawa-Kraków, Poland: PWN, 7:261-269.

Kociecki S; Zdanowski A, Kolk A et al. , 1991. Mala Encyklopedia Lesna. [Small Encyclopedia of Forestry.] Warszawa, Poland: PWN.

Marca Ola; Gambi L; Pignatti G; Sanesi G, 1998. Studies of the vegetation and environment on a rehabilitated domestic waste landfill site. Monti e Boschi, 49(1):13-23; 12 ref.

Meusel H; Jäger E; Weinert E, 1965. Vergleichende Chorologie der zentraleuropäischen Flora. Jena, Germany: Fischer.

Mitchell A; Wilkinson J, 1991. The trees of Britain and Northern Europe. London, UK: Collins.

Owen SJ, 1996. Ecological weeds on conservation land in New Zealand: a database. Department of Conservation, Wellington, New Zealand: DOC Science Publications. http://www.hear.org/weedlists/other_areas/nz/nzecoweeds.htm

Peeters JP; Stuurman FJ, 1981. Ten years of woodland in the Broekpolder. [Tien jaar bos in de Broekpolder.] Groen, No.5, 229-242.

Polietitko OM, 1954. Boyaryshnik - Crataegus L. Dieriewya i kustarniki SSSR. Moskva-Leningrad, 3:514-577.

Puszkar T, 1981. Zadrzewienia sródpolne a choroby i szkodniki roslin uprawnych. Sylwan, 7-9:135-140.

Reichard SH; Chalker-Scott L; Buchanan S, 2001. Interactions among non-native plants and birds. In: Avian Ecology and Conservation in an Urbanising World [ed. by Marzluff JM, Bowman R, Donnelly R] Dordrecht, Netherlands: Kluwer Academic Publishers.

Rodríguez-Pérez J; Riera N; Traveset A, 2005. Effect of seed passage through birds and lizards on emergence rate of mediterranean species: differences between natural and controlled conditions. Functional Ecology, 19(4):699-706. http://www.blackwell-synergy.com/servlet/useragent?func=showIssues&code=fec

Royal Botanic Garden Edinburgh, 2007. Flora Europaea, Database of European Plants (ESFEDS). Edinburgh, UK: Royal Botanic Garden Edinburgh. http://rbg-web2.rbge.org.uk/FE/fe.html

Royal Botanic Gardens Sydney, 2007. Australia's Virtual Herbarium. Sydney, Australia: Royal Botanic Gardens. http://avhtas.tmag.tas.gov.au/

Seneta W, 1991. Drzewa i krzewy lisciaste. Tom. 2. [Deciduous trees and shrubs. Vol. 2]. Warszawa, Poland: PWN.

St John S, 1982. Acid treatment of seeds of Crataegus monogyna and other Crataegus species. Combined Proceedings, International Plant Propagators' Society, 32: 203-205.

Stace C, 1997. New flora of the British Isles. Second edition. Cambridge, UK: Cambridge University Press.

USDA; NRCS, 2007. The PLANTS Database. Baton Rouge, USA: National Plant Data Center. http://plants.usda.gov/

USDA-ARS, 2007. Germplasm Resources Information Network (GRIN). Online Database. Beltsville, Maryland, USA: National Germplasm Resources Laboratory. https://npgsweb.ars-grin.gov/gringlobal/taxon/taxonomysearch.aspx

Walter H; Lieth H, 1960. World atlas of climate diagrams. [Klimadiagramm-Weltatlas.] pp. 86 [loose-leaf]. Many refs. Jena, Germany; Gustav Fischer Verlag.

Williams PA; Buxton RP, 1986. Hawthorn (Cratpgus monogyna) populations in mid-Canterbury. New Zealand Journal of Ecology, 9:11-17

Wilson M; Epton HAS; Sigee DC, 1990. Biological control of fire blight of hawthorn. Acta Horticulturae, No. 273:363-365

Wojterska M, 1990. Mezofilne zbiorowiska zaroslowe Wielkopolski. Prace Komisji Biologicznej Poznanskiego Towarzystwa Przyjaciól Nauk, 72. Warszawa-Poznan, Poland: PWN.

Zajaczkowski, 1998. Ekspert. Program wspomagajacy dobór drzew i krzewów do zadrzewien. ['Expert'. A computer program helping in choice of trees and shrubs to be planted along roads and motorways]. Wersja 1.2. Wydzial Lesny SGGW w Warszawie. Further information at the official World Wide Web site of the Ministry of Environmetal Protection, Natural Resources and Forestry, Republic of Poland. http://www.mos.gov.pl/mos/publikac/ekspert/index.html.

Distribution References

Australia, Royal Botanic Gardens Sydney, 2007. Australia's Virtual Herbarium. In: Australia's Virtual Herbarium, Sydney, Australia: Royal Botanic Gardens. http://avhtas.tmag.tas.gov.au/

Bass D A, Crossman N D, Lawrie S L, Lethbridge M R, 2006. The importance of population growth, seed dispersal and habitat suitability in determining plant invasiveness. Euphytica. 148 (1/2), 97-109. DOI:10.1007/s10681-006-5944-6

CABI Data Mining, Undated. CAB Abstracts Data Mining.,

CABI, 2005. Forestry Compendium. In: Forestry Compendium, Wallingford, UK: CABI.

CABI, Undated. CABI Compendium: Status as determined by CABI editor. Wallingford, UK: CABI

Hunter J C, Mattice J A, 2002. The spread of woody exotics into the forests of a northeastern landscape, 1938-1999. Journal of the Torrey Botanical Society. 129 (3), 220-227. DOI:10.2307/3088772

Owen S J, 1996. Ecological weeds on conservation land in New Zealand: a database. In: Ecological weeds on conservation land in New Zealand: a database, Department of Conservation, Wellington, New Zealand: DOC Science Publications. http://www.hear.org/weedlists/other_areas/nz/nzecoweeds.htm

Reichard S H, Chalker-Scott L, Buchanan S, 2001. Interactions among non-native plants and birds. In: Avian Ecology and Conservation in an Urbanising World. [ed. by Marzluff J M, Bowman R, Donnelly R]. Dordrecht, Netherlands: Kluwer Academic Publishers.

Royal Botanic Garden Edinburgh, 2007. Flora Europaea, Database of European Plants (ESFEDS). In: Flora Europaea, Database of European Plants (ESFEDS), Edinburgh, UK: Royal Botanic Garden Edinburgh. http://rbg-web2.rbge.org.uk/FE/fe.html

USDA-ARS, 2007. Germplasm Resources Information Network (GRIN). Online Database. In: Germplasm Resources Information Network (GRIN). Online Database, Beltsville, USA: National Germplasm Resources Laboratory. http://www.ars-grin.gov/cgi-bin/npgs/html/tax_search.pl

USDA-NRCS, 2007. The PLANTS Database., Greensboro, North Carolina, USA: USA National Plant Data Team. https://plants.sc.egov.usda.gov

Contributors

11/01/2008 Updated by:

Nick Pasiecznik, Consultant, France

Distribution Maps