Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Datasheet

Sonchus oleraceus
(common sowthistle)

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Datasheet

Sonchus oleraceus (common sowthistle)

Summary

  • Last modified
  • 20 November 2018
  • Datasheet Type(s)
  • Invasive Species
  • Pest
  • Host Plant
  • Preferred Scientific Name
  • Sonchus oleraceus
  • Preferred Common Name
  • common sowthistle
  • Taxonomic Tree
  • Domain: Eukaryota
  •   Kingdom: Plantae
  •     Phylum: Spermatophyta
  •       Subphylum: Angiospermae
  •         Class: Dicotyledonae
  • Summary of Invasiveness
  • S. oleraceus is a common seed crop contaminant and has been carried either deliberately or accidentally by humans to almost every corner of the earth, where it invades mainly open and disturbed areas. It grows...

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Pictures

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PictureTitleCaptionCopyright
S. oleraceus plantule with five proper leaves.  Leaves have small, soft teeth, with two pointed auricles at the limb base.
TitleLeaves
CaptionS. oleraceus plantule with five proper leaves. Leaves have small, soft teeth, with two pointed auricles at the limb base.
CopyrightC. Chirila
S. oleraceus plantule with five proper leaves.  Leaves have small, soft teeth, with two pointed auricles at the limb base.
LeavesS. oleraceus plantule with five proper leaves. Leaves have small, soft teeth, with two pointed auricles at the limb base.C. Chirila
TitleSeedling
Caption
CopyrightNOVARTIS
SeedlingNOVARTIS
Left, upper part of stem before flowering, showing leaves with pointed auricles; right, mature S. oleraceus plant on the edge of a maize crop.
TitleGrowth habit
CaptionLeft, upper part of stem before flowering, showing leaves with pointed auricles; right, mature S. oleraceus plant on the edge of a maize crop.
CopyrightC. Chirila
Left, upper part of stem before flowering, showing leaves with pointed auricles; right, mature S. oleraceus plant on the edge of a maize crop.
Growth habitLeft, upper part of stem before flowering, showing leaves with pointed auricles; right, mature S. oleraceus plant on the edge of a maize crop.C. Chirila
Leaves large, alternate, soft, glabrous and dull-green, with violet shades in autumn. 20-50 flower-heads, each containing 80-250 yellow flowers which are longer than the involucre. Thistledown is white and persistent.
TitleFlowers and leaves
CaptionLeaves large, alternate, soft, glabrous and dull-green, with violet shades in autumn. 20-50 flower-heads, each containing 80-250 yellow flowers which are longer than the involucre. Thistledown is white and persistent.
CopyrightNOVARTIS
Leaves large, alternate, soft, glabrous and dull-green, with violet shades in autumn. 20-50 flower-heads, each containing 80-250 yellow flowers which are longer than the involucre. Thistledown is white and persistent.
Flowers and leavesLeaves large, alternate, soft, glabrous and dull-green, with violet shades in autumn. 20-50 flower-heads, each containing 80-250 yellow flowers which are longer than the involucre. Thistledown is white and persistent.NOVARTIS
S. oleraceus leaf, green, greasy to touch and smooth.
TitleLeaf - line drawing
CaptionS. oleraceus leaf, green, greasy to touch and smooth.
CopyrightNOVARTIS
S. oleraceus leaf, green, greasy to touch and smooth.
Leaf - line drawingS. oleraceus leaf, green, greasy to touch and smooth.NOVARTIS
S. oleraceus fruit (4x natural size, transverse section 8x).
TitleFruit - line drawing
CaptionS. oleraceus fruit (4x natural size, transverse section 8x).
CopyrightNOVARTIS
S. oleraceus fruit (4x natural size, transverse section 8x).
Fruit - line drawingS. oleraceus fruit (4x natural size, transverse section 8x).NOVARTIS
Roots in different stages of plant growth. Roots are upright with many branches, especially near the soil surface.
TitleRoot growth stages
CaptionRoots in different stages of plant growth. Roots are upright with many branches, especially near the soil surface.
CopyrightC. Chirila
Roots in different stages of plant growth. Roots are upright with many branches, especially near the soil surface.
Root growth stagesRoots in different stages of plant growth. Roots are upright with many branches, especially near the soil surface.C. Chirila

Identity

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Preferred Scientific Name

  • Sonchus oleraceus L.

Preferred Common Name

  • common sowthistle

Other Scientific Names

  • Sonchus angustissimus Hook.f.
  • Sonchus australis Hort. ex Trev.
  • Sonchus ciliatus Lamarck
  • Sonchus fabrae Sennen
  • Sonchus gracilis Phil.
  • Sonchus jacinthoides DC.
  • Sonchus lacerus. Willd.
  • Sonchus laevis Vill.
  • Sonchus laevis camer ex Sch.Bip
  • Sonchus longifolius Trevir
  • Sonchus pallescens Panc.
  • Sonchus parviflorus Lej.
  • Sonchus reversus E.Mey. ex DC
  • Sonchus rivularis Phil.
  • Sonchus roseus Besser ex Spreng
  • Sonchus royleanus DC.
  • Sonchus schimperi A.Braun & Bouch
  • Sonchus schmidianus K.Koch
  • Sonchus spinulifoius Sennen
  • Sonchus subbipinnatifidus (Guss.) Zenari
  • Sonchus sundaicus Blume
  • Sonchus umbellifer Thunb.
  • Sonchus zacinthoides DC.

International Common Names

  • English: annual sowthistle; colewort; field sow-thistle; hare’s lettuce; hare’s thistle; milk thistle; small sow thistle; smooth sowthistle; sow thistle; sowthistle
  • Spanish: borraja; cerraja comun; chinita; envidia; lechecino; lechugilla; muela de caballo
  • French: laiteron lisse; laiteron maraicher
  • Chinese: ku gu cai
  • Portuguese: serralha-lisa; serralha-macia

Local Common Names

  • : borraja; colmillo de leon; serraja; serrajilla
  • Brazil: chicória-brava; laiteron potager; serradela-branca
  • Canada: laiteron commum
  • Chile: nirhue
  • Cuba: algodoncillo; cerraja; cerraja lechosa
  • Dominican Republic: achicoria; borraja; borraja morada; chicoria; lechuguillo
  • Germany: Gewoehnliche Gaensedistel; Kohl-Gänsedistel
  • Haiti: chicorée marrón
  • Italy: cicerbita; crespigna; crespino liscio; sonco
  • Japan: harunonogeshi; nogeshi
  • Lesser Antilles: bouton blanc; herbe à lapin; laitue
  • Mexico: achicoria dulce; borrajilla; cardo; endivia; falso diente de león; mitihuaraca; muela de caballo
  • Morocco: oulden-en-mahja
  • Netherlands: gewone Melkdistel
  • Puerto Rico: achicoria; achicoria silvestre
  • Russian Federation: osot ogorodny
  • Saudi Arabia: kuwwaysh
  • Sweden: mjoelktistel

EPPO code

  • SONOL (Sonchus oleraceus)

Summary of Invasiveness

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S. oleraceus is a common seed crop contaminant and has been carried either deliberately or accidentally by humans to almost every corner of the earth, where it invades mainly open and disturbed areas. It grows in a wide variety of environments on a wide range of substrates – roadsides, cultivated land, gardens, construction sites, sand dunes, logged or burned areas, on walls, mountain slopes, and near water. Once introduced to a new area the plants spread quickly because they grow and flower quickly and produce copious wind- and bird-dispersed seeds that germinate quickly in large numbers. They invade many cropped areas, especially among vegetable and winter crops. They are almost perfect ‘designer weeds’. Additionally, this species has small light seeds which are easily dispersed by wind and water. 

Taxonomic Tree

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

Notes on Taxonomy and Nomenclature

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Asteraceae is one of the most species rich families among the group of flowering plants. This family includes 1620 genera and about 23,600 species (Stevens, 2012). Species within the Asteraceae are very variable in their growth form and habitat, but may be recognized by their “capitulate” and involucrate inflorescences in which numerous small flowers open first on the outside and are infrequently subtended by bracts. The anthers in this family are usually fused and form a tube through which the style extends before the two stigmatic lobes separate and become recurved. The rather small, single-seeded fruits usually have a plumose “pappus” and are frequently dispersed by wind (Stevens, 2012).

The genus Sonchus includes approximately 60 species, and three of them have become common weeds throughout the world. These are S. arvensis, perennial sow thistle, and the two annual species S. oleraceus, common sow thistle, and S. asper, prickly sow thistle.

S. oleraceus belongs to the Lactuceae tribe, subfamily Lactucoidae, of the family Asteraceae (Audus and Heywood, 1980). The species has previously been placed in the Crepideae tribe, subfamily Liguliflorae (Nyárády, 1965). Stebbins (1953) is reported in Hutchinson et al. (1984) as suggesting that S. oleraceus is an amphidiploid which received 18 chromosomes from S. asper and 14 from S. tenerrimus.

Description

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S. oleraceus is an annual and sometimes biennial herb, 40-150 cm tall, containing white latex in all plant parts. The taproot is upright with many branches, especially near the soil surface. Stem below synflorescence simple or branched, glabrous. Basal and lower stem leaves with basal portion petiole-like and attenuate, mostly smaller than middle stem leaves, otherwise similar. Middle and upper stem leaves extremely variable, elliptic, oblanceolate, or lanceolate, 6-20 × 2-9 cm, almost entire to ± irregularly, soft, glabrous, adaxially dull green, base auriculately clasping with auricles usually acutely prostrate, margin ± coarsely spinulosely dentate, apex acute; lateral lobes triangular to elliptic, usually recurved, apex acute to acuminate; terminal lobe larger than others, broadly triangular, broadly hastate, or obovate-cordate. Synflorescence shortly corymbiform or racemiform, with few to several capitula. The flower-head has a green involucre consisting of 27-35 lance-shaped bracts, 10-13 mm long and hairy while young. Each flower-head contains 80-250 ligulate flowers which are longer than the involucre. The flowers are yellow and the ligule is about as long as the corolla tub. Achenes are brown, 2.5-3.75 x 0.7-1 mm, oblanceolate, and transversely tuberculate-rugose. Thistledown is white and persistent. One plant may produce 4000-6000 seeds or more (Nyárády, 1965; Anghel et al., 1972; Boulos, 1976; Hutchinson et al., 1984; Ciocârlan, 1990).

Distribution

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S. oleraceus originates from Europe (Munz, 1968; Gleason and Cronquist, 1991; Matthei et al., 1993), Northern Africa and Western Asia (Hegi, 1929; Garcke, 1972). It has spread to North and South America, India, China, Australia (Hegi, 1929; Grieson, 1980), Pacific Isles (Lambinon et al., 1992) and the Antarctic Isles (Walter, 1968). It is considered a cosmopolitan species by Ciocârlan V (1990) and Gleason and Cronquist (1991) and subcosmopolitan by Lambinon et al. (1992).

In countries with extensive farming practices, although S. oleraceus is widespread, some quantitative distinctions can be made based on favourable conditions for the species. For example, it occurs in all the states of the USA, but a greater density is recorded along the Pacific Coast, as well as in south-western and south-eastern states (Anonymous, 1976).

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

AfghanistanPresentNativeKirpichnikov, 1964; USDA-ARS, 2014
ArmeniaPresentNativeUSDA-ARS, 2014
AzerbaijanPresentNativeKirpichnikov, 1964; USDA-ARS, 2014
BahrainPresentAbbas et al., 1992
BhutanPresentIntroducedParker, 1992; USDA-ARS, 2014Naturalized
CambodiaPresentIntroducedUSDA-ARS, 2014Naturalized
ChinaWidespreadAnon., 1975; Wang et al., 1990; Grieson, 1980
-AnhuiPresentIntroducedFlora of China Editorial Committee, 2014Naturalized
-FujianPresentIntroducedFlora of China Editorial Committee, 2014Naturalized
-GansuPresentIntroducedFlora of China Editorial Committee, 2014; Flora of China Editorial Committee, 2014Naturalized
-GuangxiPresentIntroducedFlora of China Editorial Committee, 2014Naturalized
-GuizhouPresentIntroducedFlora of China Editorial Committee, 2014Naturalized
-HainanPresentIntroducedFlora of China Editorial Committee, 2014Naturalized
-HebeiPresentIntroducedFlora of China Editorial Committee, 2014
-Hong KongPresent
-HubeiPresentIntroducedFlora of China Editorial Committee, 2014Naturalized
-HunanPresentIntroducedFlora of China Editorial Committee, 2014
-JiangsuPresentIntroducedFlora of China Editorial Committee, 2014Naturalized
-JiangxiPresentIntroducedFlora of China Editorial Committee, 2014Naturalized
-LiaoningPresentIntroducedFlora of China Editorial Committee, 2014Naturalized
-NingxiaPresentIntroducedFlora of China Editorial Committee, 2014Naturalized
-QinghaiPresentIntroducedFlora of China Editorial Committee, 2014Naturalized
-ShaanxiPresentIntroducedFlora of China Editorial Committee, 2014Naturalized
-ShandongPresentIntroducedFlora of China Editorial Committee, 2014Naturalized
-ShanxiPresentIntroducedFlora of China Editorial Committee, 2014Naturalized
-TibetPresentIntroducedFlora of China Editorial Committee, 2014Naturalized
-XinjiangPresentIntroducedFlora of China Editorial Committee, 2014Naturalized
-YunnanPresentIntroducedFlora of China Editorial Committee, 2014Naturalized
-ZhejiangPresentIntroducedFlora of China Editorial Committee, 2014Naturalized
Christmas Island (Indian Ocean)PresentIntroduced Invasive Queensland Department of Primary Industries and Fisheries, 2011
Cocos IslandsPresentIntroducedQueensland Department of Primary Industries and Fisheries, 2011
Georgia (Republic of)PresentNativeKirpichnikov, 1964; USDA-ARS, 2014
IndiaPresentNasir et al., 1972; Grieson, 1980
-Arunachal PradeshPresentIntroduced Invasive Chandra, 2012
-AssamPresentIntroduced Invasive Chandra, 2012
-Himachal PradeshPresentIntroduced Invasive Chandra, 2012
-Jammu and KashmirPresentIntroduced Invasive Chandra, 2012
-ManipurPresentIntroduced Invasive Chandra, 2012
-MeghalayaPresentIntroduced Invasive Chandra, 2012
-MizoramPresentIntroduced Invasive Chandra, 2012
-NagalandPresentIntroduced Invasive Chandra, 2012
-SikkimPresentIntroduced Invasive Chandra, 2012
-TripuraPresentIntroduced Invasive Chandra, 2012
-UttarakhandPresentIntroduced Invasive Chandra, 2012
-West BengalPresentIntroduced Invasive Chandra, 2012
IndonesiaPresentIntroducedUSDA-ARS, 2014Naturalized
IranPresentNativeHolm et al., 1977; USDA-ARS, 2014
IraqPresentNativeUSDA-ARS, 2014
IsraelPresentNativeKirpichnikov, 1964; USDA-ARS, 2014
JapanPresentIntroduced Invasive Holm et al., 1977; Yamaguchi, 1992
JordanPresentNativeUSDA-ARS, 2014
KazakhstanPresentNativeKirpichnikov, 1964; USDA-ARS, 2014
Korea, DPRPresentNativeUSDA-ARS, 2014
Korea, Republic ofPresentNativeUSDA-ARS, 2014
KyrgyzstanPresentNativeKirpichnikov, 1964; USDA-ARS, 2014
LebanonPresentNativeUSDA-ARS, 2014
MalaysiaPresentIntroducedUSDA-ARS, 2014Naturalized
MongoliaPresentIntroducedUSDA-ARS, 2014Naturalized
MyanmarPresentIntroducedUSDA-ARS, 2014Naturalized
NepalPresentIntroducedUSDA-ARS, 2014Naturalized
OmanPresentIntroducedUSDA-ARS, 2014Naturalized
PakistanPresentNativeNasir et al., 1972; USDA-ARS, 2014
PhilippinesPresentIntroduced Invasive Holm et al., 1977
Saudi ArabiaPresentMandaville, 1990
Sri LankaPresentIntroducedGrieson, 1980; USDA-ARS, 2014Naturalized
SyriaPresentNativeUSDA-ARS, 2014
TaiwanPresentIntroduced Invasive Flora of China Editorial Committee, 2014
TajikistanPresentVasilcenko, 1953; Kirpichnikov, 1964; USDA-ARS, 2014
ThailandPresentIntroducedUSDA-ARS, 2014Naturalized
TurkeyPresentNativeUSDA-ARS, 2014
TurkmenistanPresentNikitin, 1957; Kirpichnikov, 1964
UzbekistanPresentHudaikulov, 1956; Vvedenski, 1962
VietnamPresentIntroduced Invasive USDA-ARS, 2014
YemenPresentSchwartz, 1939; USDA-ARS, 2014

Africa

AlgeriaPresentNativeQuezel and Santa, 1963; USDA-ARS, 2014
AngolaPresentIntroducedUSDA-ARS, 2014Naturalized
BotswanaPresentIntroducedUSDA-ARS, 2014Naturalized
BurundiPresentIntroducedUSDA-ARS, 2014Naturalized
CameroonPresentIntroducedUSDA-ARS, 2014Naturalized
Cape VerdePresentIntroducedUSDA-ARS, 2014Naturalized
EgyptPresentTõckholm, 1974; Schwartz, 1939; USDA-ARS, 2014
Equatorial GuineaPresentIntroducedUSDA-ARS, 2014Naturalized
EritreaPresentIntroducedUSDA-ARS, 2014Naturalized
EthiopiaPresentIntroducedUSDA-ARS, 2014Naturalized
GhanaPresent
GuineaPresentIntroducedUSDA-ARS, 2014Naturalized
KenyaPresentIntroducedUSDA-ARS, 2014Naturalized
LesothoPresentIntroducedUSDA-ARS, 2014Naturalized
LibyaPresentNativeTõckholm, 1974; USDA-ARS, 2014
MalawiPresentIntroducedTerry and Michieka, 1987; USDA-ARS, 2014Naturalized
MaliPresentIntroducedUSDA-ARS, 2014Naturalized
MauritiusPresentIntroduced Invasive Holm et al., 1977
MoroccoPresentNativeNègre, 1962; USDA-ARS, 2014
MozambiquePresentIntroducedUSDA-ARS, 2014Naturalized
NamibiaPresentIntroducedUSDA-ARS, 2014Naturalized
NigeriaPresentIntroducedUSDA-ARS, 2014Naturalized
RéunionPresentIntroducedUSDA-ARS, 2014Naturalized
Rodriguez IslandPresentIntroduced Invasive Holm et al., 1977
RwandaPresentIntroducedUSDA-ARS, 2014Naturalized
SenegalPresentUSDA-ARS, 2014
SomaliaPresentIntroducedUSDA-ARS, 2014Naturalized
South AfricaPresentIntroduced Invasive Grieson, 1980; Henderson, 2007
Spain
-Canary IslandsPresentBoulos, 1976; Siverio et al., 2011
SudanPresentBrown & Massey, 1929
SwazilandPresentIntroducedUSDA-ARS, 2014Naturalized
TanzaniaPresentTerry and Michieka, 1987; USDA-ARS, 2014
TunisiaPresentNativeUSDA-ARS, 2014
UgandaPresentIntroducedTerry and Michieka, 1987; USDA-ARS, 2014Naturalized
ZambiaWidespreadTerry and Michieka, 1987; USDA-ARS, 2014
ZimbabwePresentIntroducedUSDA-ARS, 2014Naturalized

North America

BermudaPresentMoore, 1906
CanadaPresentHutchinson et al., 1984
-AlbertaPresentIntroducedUSDA-NRCS, 2014
-British ColumbiaPresentIntroducedUSDA-NRCS, 2014
-ManitobaPresentIntroducedUSDA-NRCS, 2014
-New BrunswickPresentIntroducedUSDA-NRCS, 2014
-Newfoundland and LabradorPresentIntroducedUSDA-NRCS, 2014
-Northwest TerritoriesPresentIntroducedUSDA-NRCS, 2014
-Nova ScotiaPresentIntroducedUSDA-NRCS, 2014
-OntarioPresentIntroducedUSDA-NRCS, 2014
-Prince Edward IslandPresentIntroducedUSDA-NRCS, 2014
-QuebecPresentIntroducedUSDA-NRCS, 2014
-SaskatchewanPresentIntroducedUSDA-NRCS, 2014
GreenlandPresentIntroducedDAISIE, 2014
MexicoPresentIntroduced Invasive Vibrans, 2009
Saint Pierre and MiquelonPresentIntroducedUSDA-NRCS, 2014
USAWidespreadAnon., 1976; Gleason and Cronquist, 1991
-AlabamaPresentIntroduced Invasive USDA-NRCS, 2014
-AlaskaPresentUSDA-NRCS, 2014
-ArizonaPresentIntroduced Invasive
-ArkansasPresentIntroduced Invasive USDA-NRCS, 2014
-CaliforniaPresentIntroduced Invasive USDA-NRCS, 2014
-ColoradoPresentIntroduced Invasive USDA-NRCS, 2014
-ConnecticutPresentIntroduced Invasive USDA-NRCS, 2014
-DelawarePresentIntroduced Invasive USDA-NRCS, 2014
-District of ColumbiaPresentIntroduced Invasive USDA-NRCS, 2014
-FloridaPresentIntroduced Invasive USDA-NRCS, 2014
-GeorgiaPresentIntroduced Invasive USDA-NRCS, 2014
-HawaiiPresentIntroduced Invasive USDA-NRCS, 2014
-IdahoPresentIntroduced Invasive USDA-NRCS, 2014
-IllinoisPresentIntroduced Invasive USDA-NRCS, 2014
-IndianaPresentIntroduced Invasive USDA-NRCS, 2014
-IowaPresentIntroduced Invasive USDA-NRCS, 2014
-KansasPresentIntroduced Invasive USDA-NRCS, 2014
-KentuckyPresentIntroduced Invasive USDA-NRCS, 2014
-LouisianaPresentIntroduced Invasive USDA-NRCS, 2014
-MainePresentIntroduced Invasive USDA-NRCS, 2014
-MarylandPresentIntroduced Invasive USDA-NRCS, 2014
-MassachusettsPresentIntroduced Invasive USDA-NRCS, 2014
-MichiganPresentIntroduced Invasive USDA-NRCS, 2014
-MinnesotaPresentIntroduced Invasive USDA-NRCS, 2014
-MississippiPresentIntroduced Invasive USDA-NRCS, 2014
-MissouriPresentIntroduced Invasive USDA-NRCS, 2014
-MontanaPresentIntroduced Invasive USDA-NRCS, 2014
-NebraskaPresentIntroduced Invasive USDA-NRCS, 2014; USDA-NRCS, 2014
-NevadaPresentIntroduced Invasive USDA-NRCS, 2014
-New HampshirePresentIntroduced Invasive USDA-NRCS, 2014
-New JerseyPresentIntroduced Invasive USDA-NRCS, 2014
-New MexicoPresentIntroduced Invasive USDA-NRCS, 2014
-New YorkPresentIntroduced Invasive USDA-NRCS, 2014
-North CarolinaPresentIntroduced Invasive USDA-NRCS, 2014
-North DakotaPresentIntroduced Invasive USDA-NRCS, 2014
-OhioPresentIntroduced Invasive USDA-NRCS, 2014
-OklahomaPresentIntroduced Invasive USDA-NRCS, 2014
-OregonPresentIntroduced Invasive USDA-NRCS, 2014
-PennsylvaniaPresentIntroduced Invasive USDA-NRCS, 2014
-Rhode IslandPresentIntroduced Invasive USDA-NRCS, 2014
-South CarolinaPresentIntroduced Invasive USDA-NRCS, 2014
-South DakotaPresentIntroduced Invasive USDA-NRCS, 2014
-TennesseePresentIntroduced Invasive USDA-NRCS, 2014
-TexasPresentIntroduced Invasive USDA-NRCS, 2014
-UtahPresentIntroduced Invasive USDA-NRCS, 2014
-VermontPresentIntroduced Invasive USDA-NRCS, 2014
-VirginiaPresentIntroduced Invasive USDA-NRCS, 2014
-WashingtonPresentIntroduced Invasive USDA-NRCS, 2014
-West VirginiaPresentIntroduced Invasive USDA-NRCS, 2014
-WisconsinPresentIntroduced Invasive USDA-NRCS, 2014
-WyomingPresentIntroduced Invasive USDA-NRCS, 2014

Central America and Caribbean

AnguillaPresentIntroducedBroome et al., 2007
Antigua and BarbudaPresentIntroducedBroome et al., 2007
BahamasPresentIntroducedAcevedo-Rodriguez and Strong, 2012
BarbadosPresentIntroducedBroome et al., 2007
BelizePresentIntroducedUSDA-ARS, 2014Naturalized
British Virgin IslandsPresentIntroduced Invasive Acevedo-Rodriguez and Strong, 2012Tortola
Costa RicaPresentIntroduced Invasive Chacon and Saborio, 2012
CubaPresentIntroduced Invasive Oviedo Prieto et al., 2012
DominicaPresentIntroducedBroome et al., 2007
Dominican RepublicPresentIntroducedAcevedo-Rodriguez and Strong, 2012
El SalvadorPresentIntroducedUSDA-ARS, 2014Naturalized
GrenadaPresentIntroducedBroome et al., 2007
GuadeloupePresentIntroducedBroome et al., 2007
GuatemalaPresentIntroducedUSDA-ARS, 2014Naturalized
HaitiPresentIntroducedAcevedo-Rodriguez and Strong, 2012
HondurasPresentIntroducedUSDA-ARS, 2014Naturalized
JamaicaPresentIntroduced
MartiniquePresentIntroducedBroome et al., 2007
MontserratPresentIntroducedBroome et al., 2007
Netherlands AntillesPresentIntroducedBroome et al., 2007
NicaraguaPresentIntroducedUSDA-ARS, 2014Naturalized
PanamaPresentIntroducedUSDA-ARS, 2014Naturalized
Puerto RicoPresentKuntze, 1891; Acevedo-Rodriguez and Strong, 2012
Saint LuciaPresentIntroducedBroome et al., 2007
Saint Vincent and the GrenadinesPresentIntroducedBroome et al., 2007
Trinidad and TobagoPresentIntroducedAcevedo-Rodriguez and Strong, 2012Trinidad
United States Virgin IslandsPresentIntroduced Invasive Acevedo-Rodriguez and Strong, 2012St Thomas. St Croix, St John

South America

ArgentinaPresentIntroduced Invasive Istilart, 2005; IABIN, 2014
BrazilPresentIntroducedUsteri, 1911; USDA-ARS, 2014Naturalized
-BahiaPresentLorenzi, 1982
-Espirito SantoPresentLorenzi, 1982
-GoiasPresentLorenzi, 1982
-Mato GrossoPresentLorenzi, 1982
-Mato Grosso do SulPresentLorenzi, 1982
-Minas GeraisPresentLorenzi, 1982
-ParanaPresentLorenzi, 1982
-Rio de JaneiroPresentLorenzi, 1982
-Rio Grande do SulPresentLorenzi, 1982
-Santa CatarinaPresentLorenzi, 1982
-Sao PauloPresentLorenzi, 1982
ChilePresentJohow, 1896; USDA-ARS, 2014
-Easter IslandPresentIntroducedPIER, 2014
ColombiaPresentIntroduced Invasive USDA-ARS, 2014
EcuadorPresentIntroduced Invasive USDA-ARS, 2014
-Galapagos IslandsPresentIntroducedCharles Darwin Foundation, 2013
Falkland IslandsPresentIntroduced Invasive ISSG, 2014
ParaguayPresentIntroduced Invasive IABIN, 2014
PeruPresentIntroduced Invasive Gutte, 1978; USDA-ARS, 2014
UruguayPresentIntroduced Invasive IABIN, 2014
VenezuelaPresentIntroducedKuntze, 1891; USDA-ARS, 2014Naturalized

Europe

AlbaniaPresentNativeDemiri, 1983; USDA-ARS, 2014
AndorraPresentBoulos, 1976
AustriaPresentNativeHubl and Holzner, 1974; USDA-ARS, 2014
BelarusPresentNativeBoulos, 1976; USDA-ARS, 2014
BelgiumPresentNativeUSDA-ARS, 2014
Bosnia-HercegovinaPresentNativeBoulos, 1976; USDA-ARS, 2014
BulgariaPresentKolev, 1963; DAISIE, 2014
CroatiaPresentKovacevic, 1961; Boulos, 1976; USDA-ARS, 2014
CyprusPresentNativeUSDA-ARS, 2014
Czech RepublicPresentHejny, 1974; Boulos, 1976; DAISIE, 2014
Czechoslovakia (former)PresentBoulos, 1976
DenmarkPresentNativeMadsen and Jensen, 1995; USDA-ARS, 2014
EstoniaPresentNativeBoulos, 1976; USDA-ARS, 2014
FinlandPresentBoulos, 1976; DAISIE, 2014
FrancePresentNativeBoulos, 1976; USDA-ARS, 2014
-CorsicaPresentBoulos, 1976; USDA-ARS, 2014
GermanyPresentNativeGarcke, 1972; USDA-ARS, 2014
GibraltarPresentBoulos, 1976
GreecePresentHayek, 1931; Borkowsky, 1994; USDA-ARS, 2014
HungaryPresentNativeSoó, 1980; USDA-ARS, 2014
IrelandPresentNativeBoulos, 1976; USDA-ARS, 2014
ItalyPresentLorenzoni, 1963; Lorenzoni, 1978; USDA-ARS, 2014
LatviaPresentNativeFatare, 1989; USDA-ARS, 2014
LiechtensteinPresentBoulos, 1976
LithuaniaPresentNativeKirpichnikov, 1964; USDA-ARS, 2014
LuxembourgPresent
MacedoniaPresentHayek, 1931; Boulos, 1976; USDA-ARS, 2014
MaltaPresentWestra and Roodin, 1974
MoldovaPresentNativeGeideman, 1954; USDA-ARS, 2014
MonacoPresentBoulos, 1976
MontenegroPresentNativeUSDA-ARS, 2014
NetherlandsPresentNativeBoulos, 1976; USDA-ARS, 2014
NorwayPresentIntroduced Invasive Boulos, 1976; DAISIE, 2014
PolandPresentNativeRostanski, 1978; USDA-ARS, 2014
PortugalPresentNativeCoutinho, 1939; USDA-ARS, 2014
-AzoresPresentBoulos, 1976; DAISIE, 2014
-MadeiraPresentBoulos, 1976; USDA-ARS, 2014
RomaniaWidespreadCiocÔrlan, 1990; USDA-ARS, 2014
Russian FederationPresentKirpichnikov, 1964
-Eastern SiberiaPresentNativeUSDA-ARS, 2014
-Russian Far EastPresentNativeUSDA-ARS, 2014
-Western SiberiaPresentNativeUSDA-ARS, 2014
San MarinoPresentBoulos, 1976
SerbiaPresentNativeUSDA-ARS, 2014
SlovakiaPresentNativeRostanski, 1978; USDA-ARS, 2014
SloveniaPresentBoulos, 1976; Macek, 1990; USDA-ARS, 2014
SpainPresentSmythies, 1984; Alcaraz, 1984; USDA-ARS, 2014
-Balearic IslandsPresentSmythies, 1984
SwedenPresentIntroduced Invasive Boulos, 1976; DAISIE, 2014
SwitzerlandPresentSchinz and Keller, 1900; Boulos, 1976; USDA-ARS, 2014
UKPresentNativeBoulos, 1976; USDA-ARS, 2014
-Channel IslandsPresentBoulos, 1976
UkrainePresentBoulos, 1976; Soó, 1980; DAISIE, 2014
Yugoslavia (former)PresentBoulos, 1976; Soó, 1980
Yugoslavia (Serbia and Montenegro)PresentHayek, 1931; Boulos, 1976

Oceania

AustraliaPresentBoutsalis and Powles, 1995
-Australian Northern TerritoryPresentIntroducedQueensland Department of Primary Industries and Fisheries, 2011Naturalized
-New South WalesPresentIntroduced Invasive Queensland Department of Primary Industries and Fisheries, 2011
-QueenslandPresentIntroduced Invasive Queensland Department of Primary Industries and Fisheries, 2011
-South AustraliaPresentIntroduced Invasive Queensland Department of Primary Industries and Fisheries, 2011
-TasmaniaPresentIntroduced Invasive Queensland Department of Primary Industries and Fisheries, 2011
-VictoriaPresentIntroduced Invasive Queensland Department of Primary Industries and Fisheries, 2011
-Western AustraliaPresentIntroduced Invasive Queensland Department of Primary Industries and Fisheries, 2011
Cook IslandsPresentPIER, 2014
FijiPresentIntroduced Invasive Smith, 1991
French PolynesiaPresentIntroduced Invasive Florence et al., 2013
GuamPresentIntroduced Invasive PIER, 2014
KiribatiPresentIntroduced Invasive PIER, 2014
Marshall IslandsPresentIntroduced Invasive PIER, 2014
Micronesia, Federated states ofPresentIntroduced Invasive Herrera et al., 2010
New CaledoniaPresentIntroduced Invasive MacKee, 1994
New ZealandPresentIntroduced Invasive Rahman and James, 1993; ISSG, 2014
NiuePresentIntroduced Invasive PIER, 2014
Norfolk IslandPresentIntroduced Invasive Orchard, 1994
Papua New GuineaPresentIntroduced Invasive PIER, 2014
Pitcairn IslandPresentIntroduced Invasive PIER, 2014
SamoaPresentIntroducedPIER, 2014
TongaPresentIntroduced Invasive PIER, 2014
US Minor Outlying IslandsPresentIntroduced Invasive PIER, 2014
VanuatuPresentIntroducedSwarbrick, 1997
Wake IslandPresentIntroduced Invasive PIER, 2014
Wallis and Futuna IslandsPresentIntroduced Invasive PIER, 2014

History of Introduction and Spread

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In the United States, S. oleraceus was recorded in California in 1824 (Guertin, 2003). During the 1800s Europeans in large numbers settled in many parts of the world, carrying their crops (and weeds) with them. Thus they took S. oleraceus to Australia and New Zealand (and no doubt many other countries) during that expansion. In the West Indies, this species was recorded late in the 1800s and it was collected in 1885 in Puerto Rico, 1892 in Guadeloupe, and 1897 in Jamaica (US National Herbarium).

Meurk (1975) records transient introductions to the subantarctic Campbell Island in garden soil, and records that the species had previously been found near the Enderby settlement, Auckland Islands. 

Introductions

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Introduced toIntroduced fromYearReasonIntroduced byEstablished in wild throughReferencesNotes
Natural reproductionContinuous restocking
New Zealand UK 1832 Yes Webb et al. (1988) Possibly accidental
Quebec Mediterranean countries 1871 Yes Hutchinson et al. (1984) Possibly accidental
USA Europe 1824 Yes Guertin (2003) Possibly accidental
Western Australia UK 1838 Yes CHAH (2014); Council of Heads of Australasian Herbaria (2013) Possibly accidental

Risk of Introduction

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S. oleraceus is so widespread globally that few countries are not yet home to it, so its introduction to yet more countries is hardly a serious risk.

Habitat

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S. oleraceus is a common weed and can be found growing in open disturbed areas in cultivated land, gardens, sand dunes, waste places, roadsides, near waterways, burned areas, construction sites, and rail yards. It rarely grows in closed communities like forest or pasture because it needs light to germinate and grow and it is grazed by both wild and farmed livestock. In desert areas it is usually only found near waterways (Guertin, 2003). It grows from sea-level to over 2500 m (Nepal Checklist, 2014).

S. oleraceus is found on many different substrates, including saline soils, but never on acid peat (Lewin, 1948). It primarily occurs on relatively moist soils, rich in sodium, phosphorus, potassium and calcium (Kovacevic, 1961; Rehder, 1964; Hutchinson et al., 1984). The species occurs in a wide range of climates, from cool northern Canada (Hutchinson et al., 1984) to tropical Kenya and Uganda (PROTA, 2014). 

Habitat List

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CategorySub-CategoryHabitatPresenceStatus
Terrestrial
Terrestrial – ManagedCultivated / agricultural land Principal habitat Harmful (pest or invasive)
Cultivated / agricultural land Principal habitat Natural
Disturbed areas Principal habitat Harmful (pest or invasive)
Disturbed areas Principal habitat Natural
Rail / roadsides Principal habitat Harmful (pest or invasive)
Rail / roadsides Principal habitat Natural
Urban / peri-urban areas Principal habitat Harmful (pest or invasive)
Urban / peri-urban areas Principal habitat Natural
Terrestrial ‑ Natural / Semi-naturalNatural forests Present, no further details Harmful (pest or invasive)
Natural forests Present, no further details Natural
Natural grasslands Present, no further details Harmful (pest or invasive)
Natural grasslands Present, no further details Natural
Riverbanks Principal habitat Harmful (pest or invasive)
Riverbanks Principal habitat Natural
Wetlands Present, no further details Harmful (pest or invasive)
Wetlands Present, no further details Natural
Arid regions Present, no further details Harmful (pest or invasive)
Arid regions Present, no further details Natural
Littoral
Coastal areas Principal habitat Harmful (pest or invasive)
Coastal areas Principal habitat Natural
Coastal dunes Principal habitat Harmful (pest or invasive)
Coastal dunes Principal habitat Natural

Hosts/Species Affected

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S. oleraceus may occur as a weed in annual or perennial crops, particularly those which are widely-spaced or have a longer vegetation period, such as Helianthus annuus, Nicotiana tabacum, Arachis hypogaea, Phaseolus vulgaris and Citrulluslanatus. S. oleraceus competes with cultivated plants during fructification, and thus has a detrimental effect on yield (Holm et al., 1977). S. oleraceus grows well in optimally interspaced maize crops (Lorenzoni, 1963).

Growth Stages

Top of page Flowering stage, Fruiting stage, Seedling stage, Vegetative growing stage

Biology and Ecology

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Genetics

The chromosome number reported for S. oleraceus is 2n = 32 (Nyárády, 1965; Anghel et al., 1972; Boulos, 1976; Hutchinson et al., 1984; Ciocârlan, 1990) and in view of its worldwide distribution and abundance there is no threat of genetic erosion.

S. oleraceus leaves have a great plasticity. They may show different incision degrees and different shapes of the terminal lobe. The foliar limb can be pinnatifid to pinnatisect, lyrate, runcinate or almost whole. Auricles are usually pointed, but may sometimes be rounded (Gleason and Cronquist, 1991). This variability may be due to the ease of cross-breeding between species of the Sonchus genus. Nyárády (1965) describes the hybrid Sonchus x clujensis, which resembles S. asper in its green, glossy, rigid leaves, the lower ones being thorny, and resembles S. oleraceus in its upper non-thorny leaves, with pointed auricles and completely verruculose achenes. Kirpichnikov (1964) notes Sonchus x rotundifolia, a hybrid between S. oleraceus and S. asper, while Hutchinson et al. (1984) cites the opinion of other authors who claim the existence of hybrids with S. tenerrimus.

Reproductive Biology

Flowers in S. oleraceus are hermaphrodite and self-fertile, an advantage in a pioneer species with fluctuating populations that occupies sometimes marginal environments (Stebbins, 1958, cited in Harper, 1977). Flowers are insect pollinated by bees and flies and seeds are produced through both selfing and outcrossing (Hutchinson et al., 1984). Salisbury (1962), quoted in Lewin (1948), estimated 140 as the average number of achenes per capitulum, and Salisbury (1964) estimated maximum seed production of about 40,000 for a large plant.

Physiology and Phenology

S. oleraceus is an annual or winter annual species, whose seeds can germinate at any time of the year if soil temperature and moisture are adequate. Autumn- and winter-germinated seedlings spend the winter and early spring months as low-growing rosettes, and the plants only bolt (form a flowering stem) in mid to late spring. Light seems to be essential for successful germination so that burial in the soil or a vegetation cover inhibits seed germination (Sheldon 1974; Fenner, 1978). Seedling mortality can be high (Hutchinson et al., 1984).

Emergence of seedlings takes place mainly during late spring in both Canada and Britain (Hutchinson et al., 1984). Plant development may be rapid: under certain conditions capitula may be produced within 6 weeks of germination (Lewin, 1948) but this usually takes longer. Lewin (1948) observed that in Britain autumn-germinating plants produced a flowering stem in mid-March and flowered at the end of April. Seedlings germinating in March rarely flowered before the beginning of June. The plants are then in flower from June to August, and the seeds ripen from July to September.

Longevity

The plants are annuals, emerging in the spring and flowering in the following summer, or winter annuals, emerging in the autumn, overwintering in rosette form, and flowering the following spring or summer. Lewin (1948) firmly asserted that ‘in no case does the individual survive after a single flowering season’.

The species survives through seasons unfavourable to growth in the form of seeds. In laboratory storage, seeds can apparently survive for about 10 years (Ewart, 1908): in the soil Roberts and Neilson (1981) observed survival of a very low proportion (3.4 to 5 % of seeds sown) of viable seeds after 5 years. Widderick et al. (2010), in Australia, found that 12 % of seeds buried 10 cm deep survived after 30 months.

Population Size and Structure

The size and densities of populations depends on supply of seed and conditions for growth. Seedling mortality can be high, sometimes due to slug damage or damping-off fungi (Hutchinson et al., 1984).

Guthrie-Smith (1953) reported that in his hill country property in New Zealand, S. oleraceus was a ‘most prominent fire plant, temporarily possessing hundreds of acres of newly burnt forest land.’ He went on to say that millions upon millions of seedlings emerged after bush or New Zealand flax (Phormium tenax) had been burned.

Nutrition

Plants appear to grow best on fertile soils, but can survive and reproduce even on the bare sides of chalk or other cliffs, or on saline soils (Lewin, 1948).

Environmental Requirements

Light and a lack of vegetation cover seem to be the major requirement of the species, which can grow in a large range of open environments from 70o north to 50o south, and from sea level up to 2650 m altitude. In desert areas it grows in wetter places, near springs and ponds and along washes (Guertin, 2003). Seed germination can take place at temperatures ranging from 7°C to over 35°C. This species prefers light (sandy), medium (loamy) and heavy (clay) soils. The plant prefers acid, neutral and basic (alkaline) soils. It cannot grow in the shade. It requires moist soil (PROTA, 2014).

Associations

Together with other weeds, S. oleraceus forms many associations, such as Oxaleto-Chenopodietum polyspermi, Amarantho-Chenopodietum, Eclipta alba-Paspalum racemosum, and Nasturtium officinale-Commelina communis (Lorenzoni, 1978; Gutte, 1978).

Lewin (1948) said, ‘S. oleraceus exhibits such a wide range of tolerances of soil conditions that it may be found associated with any other weeds of arable land.’ The same author goes on to list the species associated with this species as a pioneer species of bare chalk, as a weed of bombed sites in London in 1943, and as part of a community on maritime cliffs in the Channel Islands. Hutchinson et al. (1984) similarly says it is a pioneer species invading sites disturbed by man, such as roadsides, cultivated land, gravel pits, logged areas, but is also common in coastal areas.

Climate

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ClimateStatusDescriptionRemark
Am - Tropical monsoon climate Tolerated Tropical monsoon climate ( < 60mm precipitation driest month but > (100 - [total annual precipitation(mm}/25]))
As - Tropical savanna climate with dry summer Tolerated < 60mm precipitation driest month (in summer) and < (100 - [total annual precipitation{mm}/25])
Aw - Tropical wet and dry savanna climate Tolerated < 60mm precipitation driest month (in winter) and < (100 - [total annual precipitation{mm}/25])
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
Cw - Warm temperate climate with dry winter Preferred Warm temperate climate with dry winter (Warm average temp. > 10°C, Cold average temp. > 0°C, dry winters)
Df - Continental climate, wet all year Preferred Continental climate, wet all year (Warm average temp. > 10°C, coldest month < 0°C, wet all year)
Ds - Continental climate with dry summer Preferred Continental climate with dry summer (Warm average temp. > 10°C, coldest month < 0°C, dry summers)
Dw - Continental climate with dry winter Preferred Continental climate with dry winter (Warm average temp. > 10°C, coldest month < 0°C, dry winters)

Latitude/Altitude Ranges

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Latitude North (°N)Latitude South (°S)Altitude Lower (m)Altitude Upper (m)
70 50

Rainfall

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ParameterLower limitUpper limitDescription
Mean annual rainfall3002800mm; lower/upper limits

Notes on Natural Enemies

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Lewin (1948) listed 23 species of insects found feeding on annual species of Sonchus, including aphids, leaf-mining and gall-forming flies, lepidoptera, mites, and nematodes. He also noted diseases recorded on the species – water moulds, botrytis, powdery mildew, and rust fungi. Hutchinson et al. (1984) listed invertebrates found attacking S. oleraceus in Canada. The list included aphids, leaf miners and nematodes (Ditylenchus destructor, Aphelenchoides ritzemabosi and Pratylenchus penetrans).

S. oleraceus is a host to fungi including Bremia sonchi, B. lactucae, Golovinomyces cichoracearum var. cichoracearum, Coleosporium tussilaginis f.sp. sonchi, Podosphaera fuliginea, Miyagia pseudosphaeria, Puccinia littoralis, Alternaria sonchi, and Aecidium sonchi.

Insects known to be specific to Sonchus spp. include Ensina hyalipennis, E. sonchi, Tephritis formosa, and Pegohylemyia sonchi.

Means of Movement and Dispersal

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Natural Dispersal (non-biotic)

The achenes are adapted for wind dispersal and the height of the relatively tall fruiting plants provides an advantage for this. Water dispersal is also possible, as the seeds can float for a few days (Praegar, 1911, in Lewin 1948).

Vector Transmission (biotic)

Humans themselves have carried the seeds of this species to very many parts of the world, whether deliberately or accidentally. Seeds can also be dispersed after being eaten by birds or mammals and then passed intact through the digestive tract (Lewin, 1948; Hutchinson et al., 1984). Salisbury (1964) included S. oleraceus in a list of species whose seeds have been raised from the excreta of various birds. Guertin (2003) noted Ridley’s (1930) observation that the species had been observed sprouting from bull finch (Pyrrhula pyrrhula) droppings. Dorph-Peterson (1924) reported that 27% of the achenes of the closely-related S. asper fed to a cow germinated in the manure. Hutchinson et al. (1984) also suggested that the pappus may tangle in feathers or wool.

Accidental Introduction

Before modern phytosanitary regulations were introduced to international trade, new settlers took vegetation from home to their new establishments in the form of hay and straw for livestock, packing for household items, stuffing for palliasses, and seed for crops and pastures. S. oleraceus, always closely associated with human activities, would naturally have been included, and this is probably how the species arrived in the Americas, Australia and elsewhere. Long-distance accidental transport of seed is less likely now.

Intentional Introduction

S. oleraceus has many medicinal and herbal uses and seed must have been deliberately taken to new lands by settlers keen to take their own cures and herbal remedies with them.

Impact Summary

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

Economic Impact

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Annual Sonchus species are commonly regarded as weeds of roadsides, waste places, gardens and cultivated land. They take up water and nutrients and thus deprive desirable plant species of these. The new seedlings require full light to flourish and presumably do not offer serious competition in the early stages of growth. However, the plants grow quite tall and shade smaller crop plants. In addition the plants may be alternate hosts for pests and diseases like aphids which, in turn, may carry economically important crop diseases. S. oleraceus is a source of infection for lettuce necrotic yellows cytorhabdovirus and beet western yellows luteovirus in Europe, Australia and North America.

S. oleraceus has become a serious weed throughout the north-eastern cropping area of Australia, where it has become a much bigger problem with the progressive switch from conventional to conservation farming systems (Widderick et al., 1981; 2010), and the spread of resistance to ALS-inhibiting herbicides. In Canada, S. oleraceus and S. asper have been designated as noxious weeds in Alberta, British Columbia. Manitoba, Ontario and Saskatchewan.

In Africa, S. oleraceus hosts many virus diseases, including watermelon mosaic virus, pepino mosaic virus, tomato spotted wilt virus and alfalfa mosaic virus. It is also a host for castor whitefly (Trialeurodes ricini), Bemisia whiteflies, cotton bollworm (Helicoverpa armigera) and the nematode Radopholus similis. S. oleraceus is apparently a preferred host for the cotton bollworm (PROTA, 2014). 

Environmental Impact

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S. oleraceus probably has relatively little direct impact on habitats or biodiversity. As an annual species it rarely invades closed vegetation and would not persist as other vegetation develops. It can, however, delay natural successional processes or impede the establishment of native species in disturbed areas.

Risk and Impact Factors

Top of page Invasiveness
  • Invasive in its native range
  • 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
  • Benefits from human association (i.e. it is a human commensal)
  • Fast growing
  • Has high reproductive potential
  • Has propagules that can remain viable for more than one year
Impact outcomes
  • Altered trophic level
  • Damaged ecosystem services
  • Ecosystem change/ habitat alteration
  • Modification of nutrient regime
  • Modification of successional patterns
  • Monoculture formation
  • Negatively impacts agriculture
  • Reduced amenity values
  • Reduced native biodiversity
  • Soil accretion
  • Threat to/ loss of native species
Impact mechanisms
  • Competition - monopolizing resources
  • Competition - shading
  • Competition - smothering
  • Rapid growth
Likelihood of entry/control
  • Highly likely to be transported internationally accidentally
  • Difficult to identify/detect as a commodity contaminant
  • Difficult to identify/detect in the field
  • Difficult/costly to control

Uses

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S. oleraceus has been consumed for peoples in many parts of the world as a salad vegetable and pot herb. Annual sow thistles (S. oleraceus and S. asper) have many uses as human food and as medicines and herbs in Africa, and Asia where they are also used for feeding cattle and other livestock.

In Africa and elsewhere. S. oleraceus is collected from the wild, but apparently it is grown commercially on a small scale in Indonesia (PROTA, 2014). In New Zealand S. oleraceus is highly valued as a green vegetable which is usually cooked with meat. The juice is used as a tonic and laxative, and the white sap can be treated to use as chewing gum (Terrain, 2013; University of Auckland, 2013). 

Similarities to Other Species/Conditions

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S. oleraceus is very similar to other members of the Sonchus genus. Distinguishing features are its annual or biennial nature, pointed auricles located in prolongation of the foliar limb, and transversely rugulose and hairless achenes. Lower leaves are petiolate, while upper ones are amplexicaul. The root is upright, 70-80 cm deep and branched only in the first 10 cm. In the unploughed layer of the soil, root branches measure only 2-3 cm (Nikitin, 1957). As a seedling, it is distinguished from other Sonchus species by its more rounded cotyledons which are cut off at the base and petiolate.

S. oleraceus differs from the very similar S. asper in its flatter, less spiky leaf margins and its sharply acute, downward pointing auricles of leaves and bracts. The ripe achenes are quite different in the two species. In S. oleraceus the achenes are narrower, never winged at the margins and are transversely rugulose and scabrous at maturity: most are brown, but those of the outermost whorl are paler and more olive in colour (Hutchinson et al., 1984).

Prevention and Control

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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.

Prevention

Eradication of S. oleraceus plants from ruderal spots close to farm crops before flowering will prevent the achene spreading by means of wind. Cultivated plant seeds must be clean and of a good quality, and seeding must ensure optimum plant density. Crop rotations must be complied with, as well as suitable timing for summer and autumn ploughing. Hoeing must be carried out as often as needed, so that sow-thistle plants do not reach the flowering stage.

Physical/Mechanical Control

Young plants are easy to pull out and the tap roots will come with them, but as the plants get older and more firmly rooted, they cannot be pulled out without breaking off the stems, which will then regrow.

Plants which are cut off above soil level recover quickly. Hutchinson et al. (1984) recommended repeated autumn tillage in milder Canadian climates, or in spring after spring emergence of seedlings. Plants do not regrow from root fragments. However, deep burial of the seeds prolongs their survival.

Biological Control

CSIRO (2007) in Australia has been exploring the possibility of biological control of this weed and has so far identified a rust fungus Miyagia pseudosphaeria, Aceria thalgi and the potential mycoherbicide pathogen, Aschochyta sonchi. The possibility of biological control had apparently been explored earlier in Canada (ISSG, 2014)

Chemical Control

A very wide range of herbicides have and are being used to control S. oleraceus either pre- or post-emergence in different crops (Hutchinson et al., 1984). However the species has now developed resistance to ALS-inhibiting herbicides such as chlorsulfuron and metsulfuron-methyl in Australia (St John-Sweeting et al., 2010). Widderick and Walker (2009) provide advice on appropriate herbicides for its control in wheat, how to manage the weed in Queensland and Northern New South Wales, and how to avoid further development and spread of herbicide resistance, including the dreadful prospect of glyphosate resistance.

Control by utilization

Cattle and sheep readily graze the plants, one of the reasons for its lack of persistence in pastures.

References

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Links to Websites

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WebsiteURLComment
GISD/IASPMR: Invasive Alien Species Pathway Management Resource and DAISIE European Invasive Alien Species Gatewayhttps://doi.org/10.5061/dryad.m93f6Data source for updated system data added to species habitat list.
Global register of Introduced and Invasive species (GRIIS)http://griis.org/Data source for updated system data added to species habitat list.

Contributors

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10/01/14 Updated by:

Julissa Rojas-Sandoval, Department of Botany-Smithsonian NMNH, Washington DC, USA

Pedro Acevedo-Rodríguez, Department of Botany-Smithsonian NMNH, Washington DC, USA


09/01/13 Updated by:

AI Popay, Consultant, Hamilton, UK

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