Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Datasheet

Cynara cardunculus
(cardoon)

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Datasheet

Cynara cardunculus (cardoon)

Summary

  • Last modified
  • 27 September 2018
  • Datasheet Type(s)
  • Invasive Species
  • Host Plant
  • Preferred Scientific Name
  • Cynara cardunculus
  • Preferred Common Name
  • cardoon
  • Taxonomic Tree
  • Domain: Eukaryota
  •   Kingdom: Plantae
  •     Phylum: Spermatophyta
  •       Subphylum: Angiospermae
  •         Class: Dicotyledonae
  • Summary of Invasiveness
  • C. cardunculus is an erect perennial herb, commonly known as cardoon or artichoke thistle. Native to southern Europe and North Africa, it has been widely introduced and is recognised as invasive in parts of Aus...

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Pictures

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PictureTitleCaptionCopyright
Cynara cardunculus (cardoon); flowering habit. Cobbler Creek, Adelaide, South Australia. December 2007
TitleFlowering habit
CaptionCynara cardunculus (cardoon); flowering habit. Cobbler Creek, Adelaide, South Australia. December 2007
Copyright©Peripitus/via wikipedia - CC BY-SA 3.0
Cynara cardunculus (cardoon); flowering habit. Cobbler Creek, Adelaide, South Australia. December 2007
Flowering habitCynara cardunculus (cardoon); flowering habit. Cobbler Creek, Adelaide, South Australia. December 2007©Peripitus/via wikipedia - CC BY-SA 3.0
Cynara cardunculus (cardoon); close view of flowers. Real Jardín Botánico de Madrid. July 2008.
TitleFlowers
CaptionCynara cardunculus (cardoon); close view of flowers. Real Jardín Botánico de Madrid. July 2008.
Copyright©Cillas/via wikipedia - CC BY-SA 4.0
Cynara cardunculus (cardoon); close view of flowers. Real Jardín Botánico de Madrid. July 2008.
FlowersCynara cardunculus (cardoon); close view of flowers. Real Jardín Botánico de Madrid. July 2008.©Cillas/via wikipedia - CC BY-SA 4.0
Cynara cardunculus (cardoon); leafy habit. USA.
TitleHabit
CaptionCynara cardunculus (cardoon); leafy habit. USA.
Copyright©John M. Randall/The Nature Conservancy/Bugwood.org - CC BY-NC 3.0 US
Cynara cardunculus (cardoon); leafy habit. USA.
HabitCynara cardunculus (cardoon); leafy habit. USA.©John M. Randall/The Nature Conservancy/Bugwood.org - CC BY-NC 3.0 US
Cynara cardunculus (cardoon); leaves. Botanische tuin TU Delft in Delft, The Netherlands. May 2006.
TitleLeaves
CaptionCynara cardunculus (cardoon); leaves. Botanische tuin TU Delft in Delft, The Netherlands. May 2006.
CopyrightPublic Domain - via wikipedia
Cynara cardunculus (cardoon); leaves. Botanische tuin TU Delft in Delft, The Netherlands. May 2006.
LeavesCynara cardunculus (cardoon); leaves. Botanische tuin TU Delft in Delft, The Netherlands. May 2006.Public Domain - via wikipedia

Identity

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Preferred Scientific Name

  • Cynara cardunculus

Preferred Common Name

  • cardoon

Other Scientific Names

  • Carduus cardunculus (L.) Baill.
  • Carduus cynara E.H.L. Krause
  • Carduus scolymus Baill.
  • Cnicus communis Lam.
  • Cynara corsica Viv.
  • Cynara ferox Ten. ex Steud.
  • Cynara horrida Aiton
  • Cynara spinosissima J. Presl & C. Presl
  • Cynara sylvestris Lam.

International Common Names

  • English: artichoke; desert artichoke; European cardoon; globe artichoke; scotch thistle; Scottish thistle; Spanish artichoke; wild artichoke; wild cardoon
  • Spanish: alcachofa; alcaucil; cardo; cardo de comer
  • French: artichaut commun; carde; cardon d’Espagne
  • Russian: artišok ispanskij
  • Arabic: al harshuff

Local Common Names

  • Finland: Isoartisokka
  • Germany: artishocke; gemüseartishocke; gemüse-artishocke; kardone
  • Italy: carciofo
  • Netherlands: kardoen
  • Portugal: alcachofra; cardo
  • Spain: card; card comestible; card comú; herbacol
  • Sweden: kardon
  • UK/England and Wales: march-ysgall

EPPO code

  • CYUCA (Cynara cardunculus)

Summary of Invasiveness

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C. cardunculus is an erect perennial herb, commonly known as cardoon or artichoke thistle. Native to southern Europe and North Africa, it has been widely introduced and is recognised as invasive in parts of Australia, the USA, Chile and Argentina. It can form dense monocultures, displacing native vegetation and degrading native plant communities. In California, it is categorized as a Most Invasive Wildland Pest Plant, category A-1, on the Californian Exotic Pest Plants of Greatest Ecological Concern. It can aggressively invade and disrupt natural habitats and has been described as a robust invasive plant that exhibits characteristics of the world’s worst weeds.

Taxonomic Tree

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  • Domain: Eukaryota
  •     Kingdom: Plantae
  •         Phylum: Spermatophyta
  •             Subphylum: Angiospermae
  •                 Class: Dicotyledonae
  •                     Order: Asterales
  •                         Family: Asteraceae
  •                             Genus: Cynara
  •                                 Species: Cynara cardunculus

Notes on Taxonomy and Nomenclature

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Cynara cardunculus is an accepted species of the Asteraceae family, sometimes referred to as the Compositae family (Weeds of Australia, 2016). The Plant List (2013) includes 44 named species from the genus Cynara, 11 of which are accepted species names. The Plant List (2013) has 17 recorded synonyms.

Cynara is derived from the Greek word, meaning ‘dog’, and cardunculus is a combination of the Latin words ‘carduus’ and ‘uncus’, meaning ‘thistle’ and ‘hook’ or ‘claw’, respectively. Thus the name, Cynara cardunculus, alludes the sharp claw like bracts around the flower head (Parsons and Cuthbertson, 2001).

C. cardunculus is commonly referred to as artichoke thistle or cardoon (Weeds of Australia, 2016). It is sometimes mistakenly referred to as globe artichoke, a closely related cultivated species (Australian Government, 2016).

Recent studies regarding the classification of the Cynara genus have sparked debate over whether the wild cardoon, cultivated cardoon (Cynara altilis) and globe artichoke (Cynara scolymus) should be classified as different species or as subspecies (CIP, 2016). Wiklund (1992) supports, through a study of morphology and phytogeography of the Cynara genus, that wild cardoon, globe artichoke and cultivated cardoon are a single species and should therefore be classified as subspecies. Rottenberg and Zohary (1996) concluded that wild cardoon is the ancestor of the cultivated globe artichoke and cardoon, further supporting the argument for the classification as subspecies.

In this datasheet, globe artichoke (C. scolymus), cultivated cardoon (C. altilis) and wild cardoon (C. cardunculus) are referred to as separate species. However, it is important to note that other sources (The Plant List, 2013; GISD, 2016) recognise these plants as varieties: cultivated artichoke C. cardunculus var. scolymus (L.) Fiori, the wild cardoon C. cardunculus var. sylvestris (Lam.) Fiori and the leafy cultivated cardoon C. cardunculus var. altilis DC (Pignone and Sonnante, 2004).  

Description

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C. cardunculus is an erect perennial herb that can grow between 60 and 150 cm, but has been known to grow as tall as 2 m with a spread of 2 m (Weeds of Australia, 2016; Elzebroek and Wind, 2008). It has a large taproot that regenerates each year (Kelly and Pepper, 1996). The root can grow to the depth of 2 m (Parsons and Cuthbertson 2001). The stems are thick and rigid, which often branch in the upper parts, they are longitudinally ribbed and covered in a cotton down. The above-ground portion of the plant dies down each year, but off-shoots rise from the rootstock next growing season (Elzebroek and Wind, 2008).

The leaves form a basal rosette that can be as large as 120 by 30 cm. The leaves further up the stem are comparatively smaller, 10-50 cm in length. The leaves are greyish-green on the upper surface and slightly hairy. On the underside they are covered in dense hair giving a white wooly appearance. Each leaf is deeply lobed, with each lobe often partly divided again. The tips of the leaves are spiked with yellowish/orange spines, 5-20 mm long.

The inflorescence occurs singly at the top of a branch on a thick stalk, 1-6 cm long. The flower heads are almost round in shape and grow to be 4-5cm across. They consist of blue, pink or purple florets arranged on a fleshy receptacle, and enclosed by a number of large bracts. The bracts are purplish in colour and taper to end in a flattened spine.

The seeds of C. cardunculus are 6-8 mm long, four sided and smooth. They are light grey, brown or black in colour, sometimes with longitudinal streaks. At the top of each seed is a circle of feathery hairs, 25-40 mm in length that readily fall off (Weeds of Australia, 2016).

Plant Type

Top of page Herbaceous
Perennial
Seed propagated

Distribution

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C. cardunculus is native to the Mediterranean basin in both southern Europe and North Africa. It has also been naturalized in parts of Australia and New Zealand, the USA, Mexico and South America (Weeds of Australia, 2016). C. cardunculus is also reported in northern parts of Europe and the Middle East, and isolated records from Central and East Asia (GBIF, 2016).

Distribution Table

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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.

Continent/Country/RegionDistributionLast ReportedOriginFirst ReportedInvasiveReferenceNotes

Asia

AzerbaijanPresentIntroducedGBIF, 2016
ChinaPresentPresent based on regional distribution.
-BeijingPresentIntroducedGBIF, 2016
IsraelPresentIntroducedGBIF, 2016Palestine
JordanPresentIntroducedGBIF, 2016
LebanonPresentIntroducedGBIF, 2016
MalaysiaPresentIntroducedGBIF, 2016
SyriaPresentIntroducedGBIF, 2016
TurkeyPresentNativeWeeds of Australia, 2016

Africa

AlgeriaPresentNativeUSDA-ARS, 2016
LibyaPresentNativeUSDA-ARS, 2016
MoroccoPresentNativeUSDA-ARS, 2016
Spain
-Canary IslandsPresentNativeWeeds of Australia, 2016
TunisiaPresentNativeUSDA-ARS, 2016

North America

MexicoPresentIntroduced Invasive PIER, 2016; USDA-ARS, 2016Guanajuato, Michoacan, Queretaro
USAPresentPresent based on regional distribution.
-CaliforniaPresentIntroduced Invasive USDA-NRCS, 2016
-OregonPresentIntroduced Invasive ISSG, 2016
-WashingtonPresentIntroduced Invasive ISSG, 2016

South America

ArgentinaPresentIntroduced Invasive GBIF, 2016; Weeds of Australia, 2016Entre Ríos, La Pampa, Argentina Distrito Federal, Mendoza, Bueno Aires, Catamarca
BrazilPresentIntroducedWeeds of Australia, 2016
-Rio Grande do SulPresentIntroducedGBIF, 2016
ChilePresentIntroduced Invasive GBIF, 2016; ISSG, 2016Valparaíso, Maule, Coquimbo, Biobio, Santiago, O’Higgins, Juan Fernandez Islands
-Easter IslandPresentIntroducedGBIF, 2016
EcuadorPresentIntroduced Invasive PIER, 2016; USDA-ARS, 2016
PeruPresent only in captivity/cultivationIntroducedUSDA-ARS, 2016
UruguayPresentIntroducedWeeds of Australia, 2016

Europe

AlbaniaPresentNativeUSDA-ARS, 2016
AndorraPresentGBIF, 2016
AustriaPresentIntroducedGBIF, 2016
BelgiumPresentIntroducedGBIF, 2016
Bosnia-HercegovinaPresentIntroducedGBIF, 2016
CroatiaPresentNativeUSDA-ARS, 2016
CyprusPresentNativeWeeds of Australia, 2016
FrancePresentNativeWeeds of Australia, 2016Southern France
GermanyPresentIntroducedGBIF, 2016
GibraltarPresentNativeGBIF, 2016
GreecePresentNativeUSDA-ARS, 2016
IrelandPresentIntroducedGBIF, 2016
ItalyPresentNativeGBIF, 2016; Weeds of Australia, 2016Sicily, Sardinia, Vatican City
LiechtensteinPresentIntroducedGBIF, 2016
LuxembourgPresentIntroducedGBIF, 2016
MaltaPresentNativeGBIF, 2016
MoldovaPresentIntroducedGBIF, 2016
MonacoPresentGBIF, 2016
NetherlandsPresentIntroducedGBIF, 2016
PortugalPresentNativeUSDA-ARS, 2016
-MadeiraPresentNativeGBIF, 2016
RomaniaPresentIntroducedGBIF, 2016
SpainPresentNativeWeeds of Australia, 2016Baleares
SwitzerlandPresentIntroducedGBIF, 2016
UKPresentIntroducedWeeds of Australia, 2016
UkrainePresentIntroducedGBIF, 2016
Yugoslavia (former)PresentNativeWeeds of Australia, 2016

Oceania

AustraliaPresentPresent based on regional distribution.
-Australian Northern TerritoryPresentAVH, 2015
-New South WalesPresentIntroduced Invasive PIER, 2016Sub-coastal regions
-QueenslandPresentIntroduced Invasive Weeds of Australia, 2016South-eastern QLD
-South AustraliaWidespreadIntroduced Invasive Weeds of Australia, 2016South-eastern SA
-TasmaniaPresentIntroducedWeeds of Australia, 2016
-VictoriaWidespreadIntroduced Invasive ISSG, 2016; Weeds of Australia, 2016
-Western AustraliaPresentIntroducedWeeds of Australia, 2016South-western WA
New CaledoniaPresentIntroducedPIER, 2016cultivated
New ZealandPresentIntroduced Invasive PIER, 2016; Weeds of Australia, 2016

History of Introduction and Spread

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C. cardunculus has been introduced and has spread in many temperate regions of the world. In the USA it is believed to have been introduced as an edible plant (Parsons and Cuthbertson, 2001). Kelly and Pepper (1996) suggest that C. cardunculus was introduced to the USA as cultivated cardoon in the mid 1800s, which subsequently escaped and propagated by seed, resulting in a reversion to its wild characteristics.

Although unconfirmed, it is likely that C. cardunculus was introduced to Australia initially for horticultural purposes. The earliest record is from Adelaide in 1839. In 1845 it was known to have been sold in a Tasmanian nursery as a culinary plant. It was also known to be sold as an ornamental flower for New Year celebrations in Melbourne. By 1879 C. cardunculus had become naturalized in South Australia (Parsons and Cuthbertson, 2001).

In South America introduction occurred earlier. This is evident by Charles Darwin’s reference to the already established and extensive spread of C. cardunculus across the South American pampas in 1833 when Darwin reached Argentina on the HMS Beagle voyage (Mack, 1989).

Introductions

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Introduced toIntroduced fromYearReasonIntroduced byEstablished in wild throughReferencesNotes
Natural reproductionContinuous restocking
Australia mid 1800s Horticulture (pathway cause) Yes Parsons and Cuthbertson (2001) Introduced from the Mediterranean basin. Earliest record in Adelaide 1839
USA mid 1800s Horticulture (pathway cause) Yes Kelly and Pepper (1996) Introduced from the Mediterranean basin. Escaped from cultivation, and subsequently propagated

Risk of Introduction

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This species is reported as a significant weed in the USA, Australia and South America. Considered to be a highly invasive species, its spread and risk of further introduction should be of concern. 

Habitat

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It is well adapted to Mediterranean regions and occurs in disturbed areas, pastures or rangelands, and undisturbed habitats such as riparian woodlands, grasslands, coastal scrub and, chaparral habitats (Kelly and Pepper, 1996).

Habitat List

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CategoryHabitatPresenceStatus
Littoral
Coastal dunes Present, no further details Harmful (pest or invasive)
Coastal dunes Present, no further details Natural
Terrestrial-managed
Cultivated / agricultural land Principal habitat Harmful (pest or invasive)
Cultivated / agricultural land Principal habitat Productive/non-natural
Disturbed areas Principal habitat Harmful (pest or invasive)
Disturbed areas Principal habitat Natural
Managed grasslands (grazing systems) Principal habitat Harmful (pest or invasive)
Managed grasslands (grazing systems) Principal habitat Natural
Rail / roadsides Present, no further details Harmful (pest or invasive)
Rail / roadsides Present, no further details Natural
Terrestrial-natural/semi-natural
Natural grasslands Present, no further details Harmful (pest or invasive)
Natural grasslands Present, no further details Natural
Riverbanks Present, no further details Harmful (pest or invasive)
Riverbanks Present, no further details Natural
Scrub / shrublands Present, no further details Harmful (pest or invasive)
Scrub / shrublands Present, no further details Natural

Hosts/Species Affected

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C. cardunculus is known to be a significant agricultural pest, in particular pastoral activity (Weeds of Australia, 2016). Once established C. cardunculus can become the dominant vegetation in an area by monopolising light, moisture and nutrients from the soil. In Australia it has known to adversely affect pastures, and lucerne, by crop contamination. The prickly nature of the herb deters grazing sheep and cattle (Parsons and Cuthbertson, 2001). A thick infestation can also limit the movement of livestock (Thomsen et al., 1986).

Host Plants and Other Plants Affected

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Plant nameFamilyContext
Medicago sativa (lucerne)FabaceaeMain

Growth Stages

Top of page Post-harvest, Vegetative growing stage

Biology and Ecology

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Reproductive Biology

C. cardunculus principally reproduces by seed, however new plants can be germinated from pieces of cut root (Parsons and Cuthbertson, 2001). Although the flowers are self-compatible, they are predominantly cross-pollinated due to protandry (Rottenberg and Zohary, 1996).

A single plant may produce more than a dozen flowers, and a single flower head can yield up to 200 seeds. Plant and flower size does vary with seasonal conditions; drier years will see smaller plants and flowers and subsequently less seeds when compared to a wetter year (Kelly, 2000).

Growth stages and life history

C. cardunculus is a perennial herb that can survive for a number of years (over 10) re-sprouting annually from its large perennial taproot (Kelly, 2000; Archontoulis et al., 2010). During it's natural cycle, cardoon sprouts in autumn, passes the winter in a rosette form and in spring develops a floral scape that dries in the summer, while the roots remain alive. Beginning in the autumn, the buds in the upper parts of the roots develop a new rosette in order to continue the cycle for several years (Bassam, 2010). Dispersed seeds primarily germinate after autumn rains, and develop slowly through winter, though germination may occur at any time of the year (Parsons and Cuthbertson, 2001). More rapid growth occurs through spring and as the flower stems develop the lower rosette leaves begin to die off. Seedlings generally do not flower in their first year, rather their energy is focused on the development of its deep taproot. New growth occurs with the autumn rains, and the cycle starts over (Parsons and Cuthbertson, 2001).

Environmental Requirements

C. cardunculus is found in a range of climates, though predominantly prefers its native Mediterranean type climate, cool humid winter and hot dry summers. It can tolerate high temperatures, and drought conditions in the summer (Archontoulis et al., 2010). Cardoon is well adapted to Mediterranean regions and occurs in disturbed areas, pastures or rangelands, and undisturbed habitats such as riparian woodlands, grasslands, coastal scrub and, chaparral habitats (Kelly and Pepper, 1996). The plant is quite sensitive to frost in the seedling stage but established plants are more frost tolerant (Neagu, 2013).

For good development of the plants, rainfall during autumn, winter and spring months should be about 400mm or more. Low rainfall significantly impacts biomass production.

C. cardunculus favours light deep and limy soils (pH optimum 6-6.8),with the capacity of retaining winter and spring water in the subsoil (1-3m). It avoids shallow calcareous soils (Pignone and Sonnante, 2004); nonetheless it can tolerate poor stony soils (Archontoulis et al., 2010). Its large vertical taproot enables the plant greater access to nutrients and water within the soil profile (Ierna and Mauromicale, 2010).

Climate

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ClimateStatusDescriptionRemark
BS - Steppe climate Tolerated > 430mm and < 860mm annual precipitation
BW - Desert climate Tolerated < 430mm annual precipitation
Cf - Warm temperate climate, wet all year Preferred Warm average temp. > 10°C, Cold average temp. > 0°C, wet all year
Cs - Warm temperate climate with dry summer Preferred Warm average temp. > 10°C, Cold average temp. > 0°C, dry summers

Latitude/Altitude Ranges

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Latitude North (°N)Latitude South (°S)Altitude Lower (m)Altitude Upper (m)
63 43

Air Temperature

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Parameter Lower limit Upper limit
Absolute minimum temperature (ºC) -23 -20
Mean annual temperature (ºC) 10 22
Mean maximum temperature of hottest month (ºC) 22
Mean minimum temperature of coldest month (ºC) -3 18

Rainfall

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ParameterLower limitUpper limitDescription
Mean annual rainfall400860mm; lower/upper limits

Rainfall Regime

Top of page Uniform
Winter

Soil Tolerances

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Soil drainage

  • free
  • seasonally waterlogged

Soil reaction

  • acid
  • alkaline
  • neutral

Soil texture

  • heavy
  • light
  • medium

Special soil tolerances

  • infertile
  • saline

Natural enemies

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Natural enemyTypeLife stagesSpecificityReferencesBiological control inBiological control on
Terellia fuscicornis Predator Seeds N

Notes on Natural Enemies

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The artichoke fly (Terellia fuscicornis) is native to the Mediterranean region and was recently accidently introduced to California. The fly’s larvae feed on the mature flower head of C. cardunculus and C. scolymus. Due to C. scolymus flower heads being cultivated prior to maturity it does not affect commercial crops (DiTomaso et al., 2013).

Means of Movement and Dispersal

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Natural Dispersal

C. cardunculus seeds are topped by a circle of feathery hairs, presumably to aid dispersal by wind, however the relatively heavy seed is only dispersed short distances in this manner (Weeds of Australia, 2016). Seeds are usually carried by wind no more than 20 m from the mother plant (Kelly, 2000). Marushia and Holt (2006) observed a dramatic difference in the dispersal distance of seeds when comparing vegetated and non-vegetated (ie. disturbed sites) sites. In non-vegetated sites, seeds were found to disperse up to 40 m, compared to 20 m in vegetated sites. However, in another study Marushia and Holt (2008) found that the main majority of seeds established themselves no more than 2 m from their mother plant. Nonetheless over a number of years the dispersal of seeds can result in large established populations of C. cardunculus (Kelly, 2000).

Kelly (2000) observed that water and gravity also play a role in the natural dispersal of seed by studying the establishment of C. cardunculus on hillsides.

Vector Transmission (Biotic)

C. cardunculus seeds are also known to be dispersed by birds, cattle, sheep and other mammals (Parsons and Cuthbertson, 2001). The seeds provide a food source for birds; as such they may carry the seeds some distance (Kelly and Pepper, 1996). In addition seeds may attach to passing animals and dispersed further distances (Kelly, 2000).

Accidental Introduction

The spread of C. cardunculus along roadsides suggests seed dispersal may be facilitated by vehicles, resulting in long distance dispersal of seeds. The ability of C. cardunculus to germinate from cut root pieces can lead to dispersal where roots have been mechanically disturbed. In addition, inappropriate disposal of roots and flower heads are a cause of dispersal (Kelly, 2000).

Intentional Introduction

Historically, in Australia, C. cardunculus was introduced for cultivation and horticultural purposes (Parsons and Cuthbertson, 2001). In the USA the presence of C. cardunculus can be attributed to the introduction of its cultivated close relatives, the globe artichoke and cultivated cardoon (Thomsen et al., 1986).

Pathway Causes

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CauseNotesLong DistanceLocalReferences
Cut flower tradeCareless disposal results in seeds being spread Yes Yes Parsons and Cuthbertson, 2001
DisturbanceCommonly colonises disturbed fields associated with overgrazing Yes Thomsen et al., 1986
HitchhikerSeeds attach to passing animals or vehicles Yes Yes Kelly, 2000
HorticultureEscaped cultivation, grown from seed C. cardunculus reverts to its wild form Yes Yes Kelly and Pepper, 1996
Ornamental purposesCareless disposal results in seeds being spread Yes Yes Parsons and Cuthbertson, 2001

Pathway Vectors

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VectorNotesLong DistanceLocalReferences
Land vehiclesSeeds Yes Yes Kelly, 2000
LivestockSeeds Yes Kelly, 2000
Machinery and equipmentRoot fragments Yes Kelly, 2000
WaterSeeds Yes Kelly, 2000
WindSeeds Yes Kelly, 2000

Impact Summary

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CategoryImpact
Economic/livelihood Positive and negative
Environment (generally) Negative
Human health Negative

Economic Impact

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C. cardunculus has had significant effect on pastoral industries. The dense populations formed by C. cardunculus displace more favourable pasture species. Grazing animals tend to avoid C. cardunculus due to its prickly form, thus reducing the pastures’ forage productivity (Weeds of Australia, 2016). Furthermore, if it exists in high densities, C. cardunculus tends to limit the movement of grazing animals (Kelly, 2000).

In addition, due to C. cardunculus ability to monopolise an area, an infestation within crops would reduce and compromise the quality of the crop yield (Weeds of Australia, 2016).

However there are a number of studies regarding the efficiency and profitability of growing C. cardunculus as a source of biomass for bioenergy in the Mediterranean region. Fernandez et al. (2006) report two products that can potentially be harvested; biomass as a solid fuel source and, seed oil for biodiesel production.

Environmental Impact

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C. cardunculus is reported to have negative environmental impacts as a highly invasive species in its non-native regions. It can form dense monocultures, displacing native vegetation and degrading native plant communities (Marushia and Holt, 2006). It can invade acres of land, out competing native flora, and creating thick monocultures as dense as 20,000 plants per acre (Kelly and Pepper, 1996). In California it is categorized as ‘Most Invasive Wildland Pest Plant’, category A-1, on the Californian Exotic Pest Plants of Greatest Ecological Concern. It can aggressively invade and disrupt natural habitats (CalEPPC, 1999) and has been described by Kelly and Pepper (1996) as a robust invasive plant that exhibits characteristics of the world’s worst weeds.

It is known to be of particular concern in disturbed and over-grazed pastures and rangelands, however it has also invaded natural habitats. Its ability to monopolise soil nutrients, water and light, and form dense populations, smother the native species. Consequently forming vast monocultures of C. cardunculus and destroying the natural habitat (Weeds of Australia, 2016). Dense invasions impede wildlife movement and displace native vegetation, causing the fragmentation of native habitats (Kelly and Pepper, 1996). One such example of C. cardunculus’ threat to native flora due to invasion and displacement is the endangered San Diego thornmint (Acanthomintha ilicifolia) (Kelly, 2000).  

Conversely, C. cardunculus does provide an abundant source of pollen for bees, and birds have been known to feed on the seeds (Parsons and Cuthbertson, 2001).

Threatened Species

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Threatened SpeciesConservation StatusWhere ThreatenedMechanismReferencesNotes
Acanthomintha ilicifoliaNatureServe NatureServe; USA ESA listing as threatened species USA ESA listing as threatened speciesCaliforniaCompetition - monopolizing resourcesKelly, 2000; USDA-NRCS, 2016

Social Impact

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Similar to its cultivated relatives, C. solymus and C. altilis, C. cardunculus is also edible and grown as a food source. In addition, C. cardunculus has been regarded for its ornamental qualities. In Australia it was once sold due to its resemblance to the Scottish floral emblem.

Close contact with C. cardunculus has been known to cause dermatitis in some people (Parsons and Cuthbertson, 2001). 

Risk and Impact Factors

Top of page Invasiveness
  • Proved invasive outside its native range
  • Has a broad native range
  • Abundant in its native range
  • Highly adaptable to different environments
  • Is a habitat generalist
  • Tolerates, or benefits from, cultivation, browsing pressure, mutilation, fire etc
  • Pioneering in disturbed areas
  • Highly mobile locally
  • Fast growing
  • Has high reproductive potential
  • Has propagules that can remain viable for more than one year
  • Reproduces asexually
  • Has high genetic variability
Impact outcomes
  • Altered trophic level
  • Ecosystem change/ habitat alteration
  • Modification of successional patterns
  • Monoculture formation
  • Negatively impacts agriculture
  • Negatively impacts human health
  • Reduced amenity values
  • Reduced native biodiversity
  • Threat to/ loss of endangered species
  • Threat to/ loss of native species
Impact mechanisms
  • Allelopathic
  • Causes allergic responses
  • Competition - monopolizing resources
  • Competition - shading
  • Produces spines, thorns or burrs
Likelihood of entry/control
  • Highly likely to be transported internationally accidentally
  • Difficult to identify/detect as a commodity contaminant
  • Difficult/costly to control

Uses

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C. cardunculus is a minor vegetable crop in much of the world except in Italy, Spain and the South of France where it is crop of regional importance and is used in traditional dishes (Lanteri and Portis, 2008).The plant is grown for its blanched leaf-stalks and leaf bases, which can be eaten as a cooked vegetable - boiled, braised or sautéed, and used in salads and soups; they have an artichoke-like flavour (Welbaum, 2015; Elzebroek and Wind, 2008). The flowers are also collected for ornamental use. In addition, in both Spain and Portugal, the pistil or ovary of the flower is used as a vegetable rennet in cheese making (iNaturalist, 2016). The seeds contains ~25% oil which is of good alimentary quality. Furthermore, the seed material left after the extraction can be used as a component of animal feed.

The plant is also a significant source of pharmaceuticals; the roots and rhizomes provide a source of inulin, a demonstrated enhancer of the human intestinal flora, and the leaves provide a source of antioxidants, such as luteolin and di-caffeoylquinic acid (Lanteri and Portis, 2008). Leaves are also considered to possess diuretic effects, improve gall bladder and liver function, and stimulate digestion. In biological assays, C. cardunculus extracts demonstrated antimicrobial activity comparable with some antibiotics (Christaki et al., 2012)

Where C. cardunculus is considered invasive, i.e. USA and Australia, it is not widely used, if at all. However its initial introduction to such places can be attributed for culinary and ornamental use (Kelly, 2000).

Furthermore, research into the cultivating of C. cardunculus as a source of biofuel is being undertaken in the Mediterranean region. Ierna and Mauromicale (2010) found that C. cardunculus is well suited to the Mediterranean climate as a low input perennially cultivated crop with high biomass and yield; as such it would be a competitive bioenergy crop and also used for paper pulp.

Uses List

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Fuels

  • Biofuels

General

  • Sociocultural value

Human food and beverage

  • Vegetable

Ornamental

  • Cut flower

Similarities to Other Species/Conditions

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As previously alluded C. cardunculus is related and similar to its cultivated forms, C. scolymus and C. altilis. The cultivated forms are selected for characteristics that are favourable for harvest and human consumption. Hence they differ from the wild form by being generally larger, with larger stems and flowers, and less spiny (iNaturalist, 2016).

In Australia, C. cardunculus may also be confused with other thistles such as, Silybum marianum,Cirsium spp., Carduus spp. and Onopordum spp.. The first of the mentioned species can be distinguished from C. cardunculus by the broad based bracts on the flower head with a curled upper part ending in a long spine. The ‘winged’ stems of the other thistle species distinguish them from C. cardunculus, which has ‘wingless’ stems (Weeds of Australia, 2016). 

Prevention and Control

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Control       

Control and eradication of C. cardunculus must be a task undertaken over a number of years. This is due to its ability to re-sprout from its perennial root and the build up of seeds that can survive up to 5 years (Kelly, 2000). Thus, ongoing detection and suppression is important in the control and eradication of C. cardunculus (Thomsen et al., 1986).

Cultural Control

In a number of states in Australia movement or sale of C. cardunculus is restricted by legislation (Weeds of Australia, 2016).

Physical/Mechanical Control

Removing individual plants is only practical where individual plants are scattered or occur in small populations. It is important to ensure the entire taproot has been removed as C. cardunculus can regrow from the cut root. This may be difficult due to the size of the taproot and depth that it can grow (Kelly, 2000). Alternatively, removing flower heads, and subsequently seeds, before they mature and become viable can slow the movement and further spread of C. cardunculus. This action can dramatically reduce the seed bank over a number of years, in turn reducing the number of new seedlings and spread (Kelly and Pepper, 1996). After removal, the plants should be taken off site and disposed of appropriately to reduce the risk of regrowth.

Mechanical methods such as ploughing, are not recommended. Removing the extensive root system mechanically would be difficult and any pieces left behind can resprout through vegetative germination. Additionally, ploughing would leave the land disturbed and open to re-infestation to C. cardunculus or other native species (Kelly, 2000).

Biological Control

Biological control is not feasible as C. cardunculus has closely related cultivated species, Cynara scolymus and Cynara altilis. It is unlikely that any biological control would therefore be restricted to C. cardunculus (Thomsen et al., 1986).

However in the USA, the accidentally introduced artichoke fly attacks the flower head of C. cardunculus. It is not an approved biocontrol agent and does not significantly affect commercial C. scolymus crops. The fly’s affect on native thistles is still being studied, and the impact on C. cardunculus populations are not known (DiTomaso et al., 2013).

Chemical Control

Several herbicides are effective in the killing of C. cardunculus when applied correctly. Two methods of application have been reported to be successful; spray application and cut stump application (Kelly, 2000). Using the spray application, Kelly and Pepper (1996) found 95-98% of plants were killed with a single application when applied as plants were bolting. This application method is suited to where there is a large C. cardunculus population.

The cut stump method provides a more accurate application and is best suited where the C. cardunculus population is sparse and is within close proximity to sensitive species, with the herbicide brushed directly onto the exposed cut stump (Kelly, 2000). Kelly and Pepper (1996) reported that this method was effective at any stage of growth with a 98-99% successful kill rate.

Ecosystem Restoration

Once C. cardunculus has been eradicated, sites are readily recolonized by displaced vegetation (Kelly, 2000).

References

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Archontoulis SV; Struik PC; Vos J; Danalatos NG, 2010. Phenological growth stages of Cynara cardunculus: codification and description according to the BBCH scale. Annals of Applied Biology, 156(2):253-270. http://www.blackwell-synergy.com/loi/aab

Australian Government, 2016. Weeds in Australia. Canberra, Australia: Australian Government. http://www.environment.gov.au/biodiversity/invasive/weeds/index.html

AVH, 2015. Australia's Virtual Herbarium. Canberra, ACT, Australia: Council of Heads of Australasian Herbaria. http://avh.chah.org.au/

CalEPPC, 1999. The CalEPPC List: Exotic Pest Plants of Greatest Ecological Concern in California. California Exotic Plant Pest Council, USA.

DiTomaso JM; Kyser GB; Oneto SR; Wilson RG; Orloff SB; Anderson LW; Wright SD; Roncoroni JA; Miller TL; Prather TS; Ransom C; Beck KG; Duncan C; Wilson KA; Mann JJ, 2013. Weed Control in Natural Areas in the Western United States. Davis, California, USA: Weed Research and Information Center, University of California, 544 pp.

Encyclopedia of Life, 2016. Encyclopedia of Life. http://www.eol.org

Fernández J; Curt MD; Aguado PL, 2006. Industrial applications of Cynara cardunculus L. for energy and other uses. Industrial Crops and Products [2005 Annual meeting of the Association for the Advancement of Industrial Crops: The international conference on industrial crops and rural development, Murcia, Spain, 17-21 September 2005.], 24(3):222-229. http://www.sciencedirect.com/science/journal/09266690

GBIF, 2016. Global Biodiversity Information Facility. http://www.gbif.org/species

GISD, 2016. Global Invasive Species Database (GISD). http://www.issg.org/database/welcome/

Ierna A; Mauromicale G, 2010. Cynara cardunculus L. genotypes as a crop for energy purposes in a Mediterranean environment. Biomass and Bioenergy, 34(5):754-760. http://www.sciencedirect.com/science/journal/09619534

iNaturalist, 2016. iNaturalist. California, USA: University of California Berkley. http://www.inaturalist.org/

ISSG, 2016. Global Invasive Species Database (GISD). Invasive Species Specialist Group of the IUCN Species Survival Commission. http://www.issg.org/database/welcome/

Kelly M, 2000. Cynara cardunculus. In: Invasive Plants of California's Wildlands [ed. by Bossard, C. C. \Randall, J. M. \and Hoshovsky, M. C.]. Berkeley, USA: University of California Press, 139-145.

Kelly M; Pepper A, 1996. Controlling Cynara cardunculus (Artichoke thistle, cardoon etc.). California Exotic Pest Plant Council, 1996 Symposium Proceedings. 5 pp.

Mack RN, 1989. Chapter 7: Temperate Grasslands Vulnerable to Plant Invasions: Characteristics and Consequences. In: Biological Invasions: A Global Perspective [ed. by Drake, J. A.]. New Jersey, USA: John Wiley & Sons Ltd, 155-179.

Marushia RG; Holt JS, 2006. The effects of habitat on dispersal patterns of an invasive thistle, Cynara cardunculus. Biological Invasions, 8(4):577-594. http://www.springerlink.com/content/g04306147l605242/?p=c42816e73ac6468db314da672538f21b&pi=2

Marushia RG; Holt JS, 2008. Reproductive strategy of an invasive thistle: effects of adults on seedling survival. Biological Invasions, 10(6):913-924. http://www.springerlink.com/content/v598p533323t6572/?p=e80f1a83898b4a429f3316170c27d647&pi=11

Neagu C, 2013. Cardoon, renewable source of energy. Scientific Papers Series - Management, Economic Engineering in Agriculture and Rural Development, 13(2):283-287. http://managementjournal.usamv.ro/pdf/vol.XIII_2/Art48.pdf

NZVH, 2016. New Zealand Virtual Herbarium. Auckland, New Zealand: New Zealand Virtual Herbarium. http://www.virtualherbarium.org.nz/home

Parsons WT; Cuthbertson EG, 2001. Noxious Weeds of Australia. Collingwood, Australia: CSIRO Publishing, 698 pp.

PFAF, 2016. Plants for a Future. http://www.pfaf.org/user/default.aspx

PIER, 2016. Pacific Island Ecosystems at Risk. Honolulu, USA: HEAR, University of Hawaii. http://www.hear.org/pier/index.html

Pignone D; Sonnante G, 2003. Wild artichokes of south Italy: Did the story begin here? Genetic Resources and Crop Evolution, 51:577-580.

Pignone D; Sonnante G, 2004. Wild artichokes of south Italy: did the story begin here? Genetic Resources and Crop Evolution, 51:577-580.

Rottenberg A; Zohary D, 1996. The wild ancestry of the cultivated artichoke. Genetic Resources and Crop Evolution, 43(1):53-58.

The Cynares International Project (CIP), 2016. The Cynares International Project (CIP). Viterbo, Italy: The Cynares International Project (CIP). http://cynares.com/index.asp

The Plant List, 2013. The Plant List: a working list of all plant species. Version 1.1. London, UK: Royal Botanic Gardens, Kew. http://www.theplantlist.org

Thomsen CD; Barbe GD; Williams WA; George MR, 1986. "Escaped" artichokes are troublesome pests. California Agriculture, 40(3-4):7-9.

USDA-ARS, 2016. Germplasm Resources Information Network (GRIN). National Plant Germplasm System. Online Database. Beltsville, Maryland, USA: National Germplasm Resources Laboratory. https://npgsweb.ars-grin.gov/gringlobal/taxon/taxonomysearch.aspx

USDA-NRCS, 2016. The PLANTS Database. Baton Rouge, USA: National Plant Data Center. http://plants.usda.gov/

Virtuella Herbariat, 2016. Virtual Herbarium, Sweden. Oskarshamn, Sweden: Virtuella Herbariat. http://www.herbarium-ume.se/virtuella_herbariet/

Weeds of Australia, 2016. Weeds of Australia, Biosecurity Queensland Edition. http://keyserver.lucidcentral.org/weeds/data/03030800-0b07-490a-8d04-0605030c0f01/media/Html/search.html?zoom_query=

Wiklund A, 1992. The genus Cynara L. (Asteraceae-Cardueae). Botanical Journal of the Linnean Society, 109(1):75-123.

Contributors

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02/03/16 Original text by: 

Diana Quiroz, Naturalis Biodiversity Center, Netherlands

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