Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Datasheet

Foeniculum vulgare
(fennel)

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Datasheet

Foeniculum vulgare (fennel)

Summary

  • Last modified
  • 22 November 2018
  • Datasheet Type(s)
  • Invasive Species
  • Host Plant
  • Preferred Scientific Name
  • Foeniculum vulgare
  • Preferred Common Name
  • fennel
  • Taxonomic Tree
  • Domain: Eukaryota
  •   Kingdom: Plantae
  •     Phylum: Spermatophyta
  •       Subphylum: Angiospermae
  •         Class: Dicotyledonae
  • Summary of Invasiveness
  • Foeniculum vulgare, also known as sweet fennel, is a common kitchen herb used around the world - but it is also a highly invasive weed that can severely damage ecosystems. A risk assessment prepared for Hawaii...

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Pictures

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PictureTitleCaptionCopyright
Foeniculum vulgare (fennel or common fennel); flower umbel.
TitleFlower umbel
CaptionFoeniculum vulgare (fennel or common fennel); flower umbel.
Copyright©Trevor James/Hamilton, New Zealand-2014
Foeniculum vulgare (fennel or common fennel); flower umbel.
Flower umbelFoeniculum vulgare (fennel or common fennel); flower umbel.©Trevor James/Hamilton, New Zealand-2014
Foeniculum vulgare (fennel or common fennel); young leaves.
TitleYoung leaves
CaptionFoeniculum vulgare (fennel or common fennel); young leaves.
Copyright©Trevor James/Hamilton, New Zealand-2014
Foeniculum vulgare (fennel or common fennel); young leaves.
Young leavesFoeniculum vulgare (fennel or common fennel); young leaves.©Trevor James/Hamilton, New Zealand-2014
Foeniculum vulgare (fennel or common fennel); detail of young leaves.
TitleYoung leaves
CaptionFoeniculum vulgare (fennel or common fennel); detail of young leaves.
Copyright©Trevor James/Hamilton, New Zealand-2014
Foeniculum vulgare (fennel or common fennel); detail of young leaves.
Young leavesFoeniculum vulgare (fennel or common fennel); detail of young leaves.©Trevor James/Hamilton, New Zealand-2014
Foeniculum vulgare (fennel or common fennel); flowering plants.
TitleFlowering plants
CaptionFoeniculum vulgare (fennel or common fennel); flowering plants.
Copyright©Trevor James/Hamilton, New Zealand-2014
Foeniculum vulgare (fennel or common fennel); flowering plants.
Flowering plantsFoeniculum vulgare (fennel or common fennel); flowering plants.©Trevor James/Hamilton, New Zealand-2014
Plant parts of fennel (F. vulgare). Line drawing, not necessarily to scale. (A) flowering branch; (B) flower at male flowering stage; (C) flower at female flowering stage; (D) fruit; (E) cross-section of fruit; (F) 'bulb' of Florence fennel.
TitleMorphology
CaptionPlant parts of fennel (F. vulgare). Line drawing, not necessarily to scale. (A) flowering branch; (B) flower at male flowering stage; (C) flower at female flowering stage; (D) fruit; (E) cross-section of fruit; (F) 'bulb' of Florence fennel.
CopyrightPROSEA Foundation
Plant parts of fennel (F. vulgare). Line drawing, not necessarily to scale. (A) flowering branch; (B) flower at male flowering stage; (C) flower at female flowering stage; (D) fruit; (E) cross-section of fruit; (F) 'bulb' of Florence fennel.
MorphologyPlant parts of fennel (F. vulgare). Line drawing, not necessarily to scale. (A) flowering branch; (B) flower at male flowering stage; (C) flower at female flowering stage; (D) fruit; (E) cross-section of fruit; (F) 'bulb' of Florence fennel.PROSEA Foundation

Identity

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Preferred Scientific Name

  • Foeniculum vulgare Miller

Preferred Common Name

  • fennel

Other Scientific Names

  • Anethum dulce DC.
  • Anethum foeniculum L.
  • Anethum minus Gouan
  • Anethum panmori Roxb.
  • Anethum pannorium Roxb.
  • Anethum rupestre Salisb.
  • Foeniculum azoricum Mill.
  • Foeniculum capillaceum Gilib.
  • Foeniculum divaricatum Griseb.
  • Foeniculum dulce Mill.
  • Foeniculum giganteum Lojac.
  • Foeniculum officinale Allioni
  • Foeniculum panmorium (Roxb.) DC.
  • Foeniculum piperitum C.Presl
  • Foeniculum rigidum Brot. ex Steud.
  • Ligusticum foeniculum (L.) Roth
  • Meum foeniculum (L.) Spreng.
  • Selinum foeniculum H.L.Krause
  • Seseli foeniculum Koso-Pol.

International Common Names

  • English: anise; aniseed; aniseed weed; bitter fennel; common fennel; Florence fennel; Roman fennel; sweet anise; sweet fennel
  • Spanish: eneldo; fonol; hinojo; lecherillo
  • French: aneth doux; fenouil; fenouil commun; fenuil doux
  • Arabic: bisbas; shamar
  • Chinese: hui xiang
  • Portuguese: funcho

Local Common Names

  • Cook Islands: taretare; taretare tui-‘ei
  • Cuba: anís de florencia; hinojo común; hinojo de Florencia
  • Czech Republic: fenikel oby; fenykl obecný
  • Dominican Republic: anís; comino
  • Fiji: pan mauri
  • French Polynesia: apiti
  • Germany: Echter Fenchel; Garten- Fenchel; Gemüsefenchel; Gewürzfenchel; wilder Fenchel
  • Guam: anis hinoho
  • Haiti: anís vert; L’buit; La nuit
  • India: saunf
  • Indonesia: adas; adas londo; hades
  • Italy: finocchio
  • Japan: fenneru; uiky; ui-kyo
  • Laos: phak s'i
  • Latvia: parast
  • Malaysia: adas pedas
  • Myanmar: samon-saba
  • Netherlands: venkel
  • Niue: taletale
  • Northern Mariana Islands: anis hinoho
  • Philippines: anis; haras
  • Puerto Rico: eneldo; esmeldo
  • Russian Federation: fenchel' obyknovennyj
  • South Africa: vinkel
  • Sweden: faenkaal; fänkål
  • Thailand: phakchi-duanha; thian-klaep; yira

EPPO code

  • FOEVU (Foeniculum vulgare)

Summary of Invasiveness

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Foeniculum vulgare, also known as sweet fennel, is a common kitchen herb used around the world - but it is also a highly invasive weed that can severely damage ecosystems. A risk assessment prepared for Hawaii gave the species a high risk score of 19 (PIER, 2015). F. vulgare is known to alter fire regimes and create dense stands, outcompeting native flora for nutrients and space (DiTomaso et al., 2013; Cal-IPC, 2015). It was listed in the Global Compendium of Weeds as an “agricultural weed, casual alien, cultivation escape, environmental weed, garden thug, naturalised, noxious weed, weed” (Randall, 2012), and is known to be invasive (mostly in natural habitats rather than agricultural land) in California, New Zealand, significant parts of Australia and a number of locations in the Pacific. (PIER, 2015).

The species is a principal weed in Mexico and New Zealand, a common weed in Argentina, Australia, Hawaii, and Spain, weedy in Chile, Morocco, Uruguay, the USA, and Venezuela, and it is known to be adventive in China, Colombia (Holm et al., 1979; Flora of China Editorial Committee, 2015; PIER, 2015; Vascular Plants of Antioquia, 2015). It is also reported as invasive in Ethiopia and Kenya. It can regenerate by both seeds and roots, which often makes physical control methods ineffective and chemical control necessary once a population is established.

Taxonomic Tree

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  • Domain: Eukaryota
  •     Kingdom: Plantae
  •         Phylum: Spermatophyta
  •             Subphylum: Angiospermae
  •                 Class: Dicotyledonae
  •                     Order: Apiales
  •                         Family: Apiaceae
  •                             Genus: Foeniculum
  •                                 Species: Foeniculum vulgare

Notes on Taxonomy and Nomenclature

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Often called the ‘carrot’ or ‘parsley’ family, the Apiaceae family consists of anise-scented, caulescent annual herbs from taproots characterized by flowers borne in rounded, compound umbels, from which the family’s traditional name of Umbelliferae is derived. The family includes many common vegetables and kitchen herbs such as celery, carrot, fennel, dill, coriander and parsnip. Foeniculum is an Old World genus of several species characterized by anise-scented leaves, stout taproots, and flowers in lax, compound umbels typical of the Apiaceae family (Wagner et al., 2015). The genus name Foeniculum derives from the Latin word ‘foenum’, hay, referring to its strong odour (Britton, 1918).

Mabberley (1997) recognises 4-5 species of Foeniculum from Asia, of which only F. vulgare has become widely naturalized. According to USDA-ARS (2013), two subspecies (F. vulgare subsp. piperitum (Ucria) Cout. – bitter fennel, and F. vulgare subsp. vulgare) are recognised, and the latter subspecies has a number of varieties, including var. azoricum (Mill.) Thell. (Florence fennel or finocchio), var. dulce (Mill.) Batt. (Roman or sweet fennel) and var. vulgare (bitter or common fennel).

Purwaningsih and Brink (1999) describe the three varieties of F. vulgare subsp. vulgare as follows:

  • cv. group Bitter Fennel or Common Fennel (other names: F. vulgare Miller var. vulgare; cultivars have fruits with a bitter aftertaste).
     
  • cv. group Florence Fennel (other names: F. azoricum Miller, F. vulgare Miller var. azoricum (Miller) Thellung, finocchio; cultivars with swollen basal part of the petiole which is eaten cooked as a vegetable).
     
  • cv. group Sweet Fennel (other names: F. dolce Miller, F. vulgare Miller var. dulce (Miller) Battand. & Trabut, Roman fennel; cultivars with sweet-tasting fruits).

Other authors use a range of other named varieties, often distinguished on the basis of the composition of their essential oil (Purwaningsih and Brink, 1999).

F. vulgare subsp. vulgare var. azoricum is commercially grown for its swollen leaf bases and edible leaves which can be eaten raw or cooked as a vegetable. The other two varieties are commercially grown for their fruits (‘seeds’) as well as vegetative parts which are used as flavouring, for essential oil production or for their medicinal properties. A reddish-leaved form called bronze fennel is often grown in gardens, and is known as F. vulgare ‘Purpureum’ or F. vulgare var. rubrum.

The invasive or weedy species is referred to as F. vulgare. DiTomaso et al. (2013) say that unlike the weedy form, cultivated varieties are seldom invasive. Possibly the cultivated varieties and forms of this species have become genetically altered over their many centuries of domestication and have lost at least some of their ‘weedy’ characteristics.

Description

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Robust, perennial, glabrous, glaucous, aromatic herb, up to 2 m tall. Stem erect, terete, longitudinally striate, profusely branched at all heights, internodes hollow when older. Leaves alternate, decompound, sheathed, lower leaves largest; leaf sheath forming an open cylinder, at base embracing the stem, 2-15 cm long, margins white scarious, sheath much larger and fleshier in Florence fennel; rest of petiole subterete, 0-10 cm longer than the sheathing part, longitudinally striate; blade triangular in outline, up to 30 cm x 50 cm, 2-6-pinnately divided into filiform, acute, blue-green lobes 1-14 cm long; primary pinnae odd-numbered 3-19. Inflorescence a terminal, compound umbel, up to 20 cm in diameter but usually smaller; peduncle (1-)5-16(-24) cm long; primary rays 5-30(-70) per umbel, 0.5-12 cm long, unequal in length, the shortest ones in the centre; secondary rays (pedicels) (2-)10-30(-45) per umbellet, up to 1 cm long, unequal in length; involucre and involucels absent; calyx vestigial at the top of the ovary; petals 5, distinct, subovate in outline, up to 1.5 mm x 1 mm, with strongly inflexed, notched apex, yellow, with a thin membranous outgrowth on the ventral side of the midrib; stamens 5, about 1.5 mm long; pistil with inferior, bilocular ovary, 2 styles, each with a stylopodium at base and a stigma at top. Fruit an ovoid-cylindrical, usually slightly curved schizocarp, 3-8.5 mm x 2-2.5 mm, light green to yellow-brown, splitting at maturity into 2 mericarps each with 5 prominent ridges and oil-vittae between the ridges. Seed with testa adnate to the pericarp. Seedling with epigeal germination (Purwaningsih and Brink, 1999).

Plant Type

Top of page Broadleaved
Herbaceous
Perennial
Seed propagated

Distribution

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F. vulgare is native to the Old World- possibly the Mediterranean region considering its use by the ancient Egyptians, Greeks and Romans- but it has been widely introduced and naturalized around the world and today is reportedly an adventive species in North, Central, and South America and the Caribbean Islands (Liogier and Martorell, 2000; Hanelt et al., 2001; Wyk, 2005; Elzebroek and Wind, 2008).

Fennels cultivated for seed are of two types: sweet fennel and bitter fennel. Sweet fennel is not found wild; it is grown in Bulgaria, France, Italy and Macedonia. Bitter fennel is grown in India, Argentina, Czech Republic, France, Germany, Hungary, Italy, Japan, Romania and Southern Russia. Indian fennel has a sweet anise flavour while the Persian fennel has a strong anise flavour and taste (Ravindran, 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

AfghanistanPresentNativeUSDA-ARS, 2013
ChinaWidespreadIntroducedeFloras, 2013Cultivated and adventive; 200-2600m. Throughout China
-Hong KongPresentIntroducedPIER, 2015Cultivated
Georgia (Republic of)PresentNativeUSDA-ARS, 2015
IndiaPresentHanelt et al., 2001
IndonesiaPresentPresent based on regional distribution.
-JavaPresentIntroducedPurwaningsih and Brink, 1999
IranPresentNativeUSDA-ARS, 2013
IsraelPresentNativeUSDA-ARS, 2013
JapanPresentIntroducedPIER, 2013
JordanPresentNativeUSDA-ARS, 2013
LebanonPresentNativeUSDA-ARS, 2013
MyanmarPresentKress et al., 2003Shan
PakistanPresentNativeUSDA-ARS, 2013
PhilippinesPresent only in captivity/cultivationIntroducedMerrill, 1923; Quisumbing, 1951‘Planted here and there about houses but nowhere spontaneous’
South East AsiaPresent only in captivity/cultivationIntroducedPurwaningsih and Brink, 1999
SyriaPresentNativeUSDA-ARS, 2013
TurkeyPresentNativeUSDA-ARS, 2013

Africa

AlgeriaPresentNativeUSDA-ARS, 2013
Cape VerdePresentIntroducedUSDA-ARS, 2013
EgyptPresentNativeUSDA-ARS, 2013
EthiopiaPresentIntroduced Invasive Witt and Luke, 2017
KenyaPresentIntroduced Invasive Witt and Luke, 2017
LibyaPresentNativeUSDA-ARS, 2013
MoroccoPresentNativeUSDA-ARS, 2013
South AfricaPresentIntroducedUSDA-ARS, 2013
Spain
-Canary IslandsPresentNativeUSDA-ARS, 2013
TunisiaPresentNativeUSDA-ARS, 2013

North America

BermudaPresentIntroducedBritton, 1918Widely distributed as a weed’
CanadaPresentPresent based on regional distribution.
-AlbertaPresentIntroducedUSDA-NRCS, 2013
-British ColumbiaPresentIntroducedUSDA-NRCS, 2013
-OntarioPresentIntroducedUSDA-NRCS, 2013
-QuebecPresentIntroducedUSDA-NRCS, 2013
MexicoPresentIntroducedUSDA-ARS, 2013; Flora Mesoamericana, 2015
USAPresentIntroducedUSDA-ARS, 2013
-ArizonaPresentIntroducedUSDA-NRCS, 2013
-CaliforniaPresentIntroduced Invasive CAL-IPC, 2005; USDA-NRCS, 2013
-ConnecticutPresentIntroducedUSDA-NRCS, 2013
-DelawarePresentIntroducedUSDA-NRCS, 2013
-FloridaPresentIntroducedUSDA-NRCS, 2013
-GeorgiaPresentIntroducedUSDA-NRCS, 2013
-HawaiiPresentIntroduced Invasive PIER, 2013; USDA-NRCS, 2013; Wagner et al., 2015
-IllinoisPresentIntroducedUSDA-NRCS, 2013
-IowaPresentIntroducedUSDA-NRCS, 2013
-KansasPresentIntroducedUSDA-NRCS, 2013
-KentuckyPresentIntroducedUSDA-NRCS, 2013
-LouisianaPresentIntroducedUSDA-NRCS, 2013
-MainePresentIntroducedUSDA-NRCS, 2013
-MarylandPresentIntroducedUSDA-NRCS, 2013
-MassachusettsPresentIntroducedUSDA-NRCS, 2013
-MichiganPresentIntroducedUSDA-NRCS, 2013
-MississippiPresentIntroducedUSDA-NRCS, 2013
-MissouriPresentIntroducedFlora of Missouri, 2015
-NebraskaPresentIntroducedUSDA-NRCS, 2013
-NevadaPresentIntroducedUSDA-NRCS, 2013
-New JerseyPresentIntroducedUSDA-NRCS, 2013
-New MexicoPresentIntroducedUSDA-NRCS, 2013
-New YorkPresentIntroducedUSDA-NRCS, 2013
-North CarolinaPresentIntroducedUSDA-NRCS, 2013
-OhioPresentIntroducedUSDA-NRCS, 2013
-OregonPresentIntroducedUSDA-NRCS, 2013
-PennsylvaniaPresentIntroducedUSDA-NRCS, 2013
-Rhode IslandPresentIntroducedUSDA-NRCS, 2013
-South CarolinaPresentIntroducedUSDA-NRCS, 2013
-TennesseePresentIntroducedUSDA-NRCS, 2013
-TexasPresentIntroducedUSDA-NRCS, 2013
-UtahPresentIntroducedUSDA-NRCS, 2013
-VirginiaPresentIntroducedUSDA-NRCS, 2013
-WashingtonPresentIntroducedUSDA-NRCS, 2013
-West VirginiaPresentIntroducedUSDA-NRCS, 2013
-WisconsinPresentIntroducedUSDA-NRCS, 2013

Central America and Caribbean

BahamasPresentIntroducedAcevedo-Rodríguez and Strong, 2012
BarbadosPresentIntroducedAcevedo-Rodríguez and Strong, 2012
BelizePresentIntroducedUSDA-ARS, 2013
Costa RicaPresentIntroducedUSDA-ARS, 2013; Flora Mesoamericana, 2015
CubaPresentIntroduced Invasive Oviedo Prieto et al., 2012
Dominican RepublicPresentIntroducedAcevedo-Rodríguez and Strong, 2012
El SalvadorPresentIntroducedUSDA-ARS, 2013
GuadeloupePresentIntroducedAcevedo-Rodríguez and Strong, 2012
GuatemalaPresentIntroducedUSDA-ARS, 2013
HondurasPresentIntroducedUSDA-ARS, 2013
JamaicaPresentIntroducedAcevedo-Rodríguez and Strong, 2012
MartiniquePresentIntroducedAcevedo-Rodríguez and Strong, 2012
Netherlands AntillesPresentIntroducedAcevedo-Rodríguez and Strong, 2012
NicaraguaPresentFlora Mesoamericana, 2015Widely cultivated and adventive
Puerto RicoPresentIntroducedLiogier and Martorell, 2000; USDA-NRCS, 2013
Saint Vincent and the GrenadinesPresentIntroducedAcevedo-Rodríguez and Strong, 2012
United States Virgin IslandsPresentIntroducedUSDA-NRCS, 2013

South America

ArgentinaPresentIntroducedUSDA-ARS, 2013
BoliviaPresentBolivia Checklist, 2015; Madidi Checklist, 2015Cultivated. Cochabamba, La Paz, Santa Cruz
BrazilPresentIntroducedUSDA-ARS, 2013
-ParanaPresentIntroducedForzza et al., 2010Subspontaneous, not endemic
-Rio Grande do SulPresentIntroducedForzza et al., 2010Subspontaneous, not endemic
-Santa CatarinaPresentIntroducedForzza et al., 2010Subspontaneous, not endemic
ChilePresentIntroduced Invasive PIER, 2013; USDA-ARS, 2013
ColombiaPresentVascular Plants of Antioquia, 2015Armenia, Guarne, Medellín, Rionegro
EcuadorPresentVascular Plants of Ecuador, 2015Azuay, Bolívar, Loja, Pichincha, Tungurahua
-Galapagos IslandsPresentPIER, 2015San Cristóbal Island. Cultivated
ParaguayPresentIntroducedUSDA-ARS, 2013
PeruPresentIntroducedPeru Checklist, 2015Andean I, Andean II, Coastal regions. Dptos Apurí, Arequipa, Cuzco, Lima, San Martín
UruguayPresentIntroducedUSDA-ARS, 2013
VenezuelaPresentIntroducedUSDA-ARS, 2013

Europe

AlbaniaPresentNativeUSDA-ARS, 2013
AustriaPresentIntroducedDAISIE, 2015Alien, not established
BelgiumPresentIntroducedDAISIE, 2015Alien, established
Bosnia-HercegovinaPresentNativeUSDA-ARS, 2015
BulgariaPresentNativeUSDA-ARS, 2013; DAISIE, 2015
CroatiaPresentNativeUSDA-ARS, 2015
Czech RepublicPresentIntroducedDAISIE, 2015Alien, not established
FinlandPresentRandall, 2012
FrancePresentNativeUSDA-ARS, 2013
GermanyPresentIntroducedDAISIE, 2015Alien, not established
GreecePresentNativeUSDA-ARS, 2013
IrelandPresentIntroducedDAISIE, 2015Cryptogenic, established
ItalyPresentNativeUSDA-ARS, 2013
LatviaPresentIntroducedDAISIE, 2015
LiechtensteinPresentIntroducedDAISIE, 2015Alien, established
MoldovaPresentIntroducedDAISIE, 2015
MontenegroPresentNativeUSDA-ARS, 2015
PortugalPresentNativeUSDA-ARS, 2013
-AzoresPresentIntroducedUSDA-ARS, 2013
-MadeiraPresentNativeUSDA-ARS, 2013
SpainPresentNativeUSDA-ARS, 2013
SwedenPresentIntroducedDAISIE, 2015Alien, not established
SwitzerlandPresentIntroducedDAISIE, 2015Alien, established
UKPresentIntroducedUSDA-ARS, 2013
-Channel IslandsPresentIntroducedDAISIE, 2015
UkrainePresentIntroducedDAISIE, 2015; USDA-ARS, 2015

Oceania

AustraliaWidespreadIntroduced Invasive University of Queensland, 2013; USDA-ARS, 2013
-New South WalesWidespreadIntroduced Invasive Parsons and Cuthbertson, 1992; University of Queensland, 2013
-QueenslandLocalisedIntroduced Invasive Parsons and Cuthbertson, 1992; University of Queensland, 2013South-eastern areas
-South AustraliaWidespreadIntroduced Invasive Parsons and Cuthbertson, 1992; University of Queensland, 2013
-TasmaniaPresentIntroducedParsons and Cuthbertson, 1992; University of Queensland, 2013
-VictoriaWidespreadIntroduced Invasive Parsons and Cuthbertson, 1992; University of Queensland, 2013
-Western AustraliaPresentIntroducedParsons and Cuthbertson, 1992; University of Queensland, 2013
Cook IslandsPresentIntroducedPIER, 2013
FijiPresentIntroduced Invasive PIER, 2013Cultivated and invasive
French PolynesiaPresentIntroduced Invasive PIER, 2013; Wagner and Lorence, 2015Cultivated (invasive in Society Islands)
GuamPresentIntroducedPIER, 2013Cultivated
Marshall IslandsPresentIntroducedPIER, 2015Cultivated
New CaledoniaPresentIntroduced Invasive PIER, 2013Cultivated, invasive
New ZealandWidespreadIntroduced Invasive Esler, 1988; Webb et al., 1988
NiuePresentIntroduced Invasive PIER, 2013

History of Introduction and Spread

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F. vulgare may be native to the Mediterranean region but it has been cultivated and consumed across Europe for centuries, as it has been well known as a spice and medicinal plant since the time of the ancient Egyptians. It has escaped from cultivation and become an invasive pest in countries with a temperate climate, but is also recorded from tropical localities like Hawaii and Fiji (PIER, 2013).

The species had symbolic significance to the Greeks, particularly in the Battle of Marathon (490 BC); Hippocrates and Dioscorides prescribed fennel as a diuretic and emmenagogue, Romans ate it as a vegetable and chewed its roots as they considered it to curb appetite and control obesity, and Pliny attributed at least twenty medicinal uses to the plant (Quisumbing, 1951; Gerard et al., 1964; Throop, 1998; Wyk, 2005; Balick, 2014). Its medicinal uses were also praised by the 9th century English Benedictine abbot Walahfrid Strabo, the 12th century German mystic Abbess Hildegard von Bingen recommended its use to treat colds, phlegm, eye afflictions, stomach ailments, and insomnia, and by 1636 Gerard wrote in his herbal that the plant was “so well knowne” among the English (Quisumbing, 1951; Gerard et al., 1964; Throop, 1998; Wyk, 2005; Balick, 2014). It was an ingredient in the common drink ‘sack’, mentioned by Shakespeare in The Tempest at the turn of the 18th century, and was an essential ingredient in absinthe, the 19th-century French drink famous for its association with Bohemian artists and writers. Salisbury (1964) comments that the species was probably introduced to Britain from the Continent before 1450. It was introduced to Australia and New Zealand in the 19th century (Parsons and Cuthbertson, 1992; Thomson, 1922).

Date of introduction to the West Indies is uncertain. It was not included in Bello’s work on Puerto Rico (Bello Espinosa, 1881; 1883). In his flora of Bermuda, Britton (1918) reported fennel to have been first introduced to Bermuda as a garden ornamental and that it had since become a widely distributed weed. It was present in the Virgin Islands before 1923, as Britton and Wilson (1923-1926) reported the species as “formerly grown as a drug in the Virgin Islands” in their survey of Puerto Rico and the Virgin Islands.

Introductions

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Introduced toIntroduced fromYearReasonIntroduced byEstablished in wild throughReferencesNotes
Natural reproductionContinuous restocking
Australia 1803 Crop production (pathway cause) Yes No Parsons and Cuthbertson (1992); Parsons and WT, Cuthbertson (1992); ParsonsWT, and Cuthbertson (1992) New South Wales
New Zealand 1864 Yes No THOMSON (1922)

Risk of Introduction

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The likelihood of introduction to new countries must be high, especially as many people relocate around the world and almost certainly take their crops and spice seeds with them. A PIER risk assessment prepared for Hawaii gave the species a high risk score of 19, where any score greater than 6 would indicate the species’ potential to be high risk and thus should be rejected for import to Australia (PIER, 2015). F. vulgare is a seriously invasive weed known to alter fire regimes and create dense stands, outcompeting native flora for nutrients and space, and thus altering the composition and structure of native communities and reducing species richness (Weber, 2003; DiTomaso et al., 2013; Cal-IPC, 2015).

The species has a rapid growth rate and its seed production is prolific, with tens of thousands of viable seeds per plant in the first season of growth, and hundreds of thousands the following year. Although cultivated varieties are seldom invasive and often grown as an annual crop in temperate areas, F. vulgare is considered an aromatic perennial and grows a deep, thick taproot that is not easily removed (DiTomaso et al., 2013). The species is known to have escaped from cultivation in Puerto Rico and possibly in the Marquesas (Liogier and Martorell, 2000; Randall, 2012; Wagner and Lorence, 2015). It is reportedly adventive in China and Colombia (Flora of China Editorial Committee, 2015; Vascular Plants of Antioquia, 2015). Considering all these factors, F. vulgare is a high-risk species.

Habitat

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F. vulgare grows on a wide range of soil types in humid-temperate regions (Parsons and Cuthbertson, 1992). It grows best in open, unshaded situations and occurs on roadsides, railway easements, channels and drains, rubbish dumps and neglected areas from which it sometimes encroaches onto more productive land. It is restricted to areas of moderate rainfall or where irrigation or run-off water is available, or to low-lying places subject to flooding. It is, apparently, reasonably frost resistant. Purwaningsih and Brink (1999) say that, as a crop, it is grown as a cold-weather crop and does not perform well in the south of India, except at higher elevations.

In California typical habitats invaded by F. vulgare include coastal sage scrub, valley grassland, oak savannah and chaparral (Bell et al., 2008). PIER (2013) describes the species’ habitats in Hawaii, Fiji, Niue and Chile: moisture, exposure to the sun and open sites seem to be common features. It occurs in disturbed areas, loams, and rocky slopes of the Andean and coastal parts of Peru (Peru Checklist, 2015), as well as the Yungas, Dry Valleys, and Dry Puna vegetation zones of Bolivia (Bolivia Checklist, 2015). In Bermuda the species was also reported to grow as a weed in fields, marshes, and waste grounds (Britton, 1918). In Missouri, USA, where the species is introduced, it is found growing around railroads, roadsides, and open, disturbed areas (Flora of Missouri, 2015). In Pakistan the species can be found growing in plains (Flora of Pakistan, 2015). 

Habitat List

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CategorySub-CategoryHabitatPresenceStatus
Terrestrial
 
Terrestrial – ManagedCultivated / 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
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
Natural grasslands Present, no further details Harmful (pest or invasive)
Riverbanks Principal habitat Harmful (pest or invasive)
Riverbanks Principal habitat Natural
Wetlands Present, no further details
Scrub / shrublands Present, no further details Harmful (pest or invasive)

Hosts/Species Affected

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A critically endangered orchid (Diuris fragrantissima) in Victoria, Australia, is threatened by invasive species, including F. vulgare (University of Queensland, 2013).

Biology and Ecology

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Genetics

2n = 16, 22, 26, 30, 44 (Wagner et al., 2015).

Reproductive Biology

Published material on factors affecting the growth of F. vulgare is abundant, mostly referring to propagation and growth of commercial crops. It is hard to know how much of this information applies to wild populations of 'weedy' F. vulgare.

Erskine-Ogden (2004), cited in CAL-IPC (2005), says that seed production is prolific – tens of thousands of seeds per plant in the first season of growth and hundreds of thousands in the second year. DiTomaso et al. (2013) claim that seeds can apparently survive for several years under field conditions.

Fennel is mainly cross-pollinated, and fruit ripening is uneven according to Purwaningsih and Brink (1999). These authors also report that seed germinates well between 15 and 20°C, with better germination in darkness than in light, and that seed retains its viability for 2-3 years.

Physiology and Phenology

Seeds normally germinate within 2-3 weeks after sowing. Initial development is slow, with a period of 2-2.5 months from sowing to stem emergence. Flowering occurs 3-4 months after sowing, and the time from sowing to first fruit harvest is 5-7 months (Purwaningsih and Brink, 1999).

Peterson et al. (1993) reported that F. vulgare initiated umbels and commenced rapid stem elongation once photoperiods exceeded 13.5 hours. At this stage, plants had developed 15 to 16 nodes below the primary umbel and had 8 to 9 expanded leaves. Fennel requires a minimum of eight fully expanded leaves and at least ten inductive cycles for umbel initiation.

Environmental Requirements

The species grows in all parts of China and has been reported at elevations between 200-2600 m (Flora of China Editorial Committee, 2015). In Colombia it has been reported growing between 1500-2500 m (Vascular Plants of Antioquia, 2015), in Ecuador between 2000-3000 m (Vascular Plants of Ecuador, 2015), and in Bolivia, at elevations up to 4000 m (Bolivia Checklist, 2015). In Pakistan, the species is commonly cultivated from the plains to 2000 m and has a wide distribution (Flora of Pakistan, 2015); it grows at a similar elevation range, 0-2000 m, in Peru (Peru Checklist, 2015).

Fennel thrives best in sunny locations in mild climates; it is primarily a cool-season crop. It prefers well-drained moist loams or loamy clay soils with pH between 6.3 and 8.3. Moisture stress should be avoided (Elzebroek and Wind, 2008). It is restricted to areas of moderate rainfall or where irrigation or run-off water is available, or to low-lying places subject to flooding. It is reasonably frost resistant (Parsons and Cuthbertson, 1992). It is grown as a cold-weather crop and does not perform well, for example, in the south of India, except at higher elevations. The tops are injured by long cold spells, so in temperate regions it is grown as an annual. Fennel is found under conditions of 500-2000(-4000) mm mean annual rainfall and 6-12(-24)°C mean annual temperature. Moisture stress causes the basal stalk to split. Fennel thrives in non-acid, well-drained loams and tolerates a soil pH between 6.3 and 8.3. It is salt-sensitive (Purwaningsih and Brink, 1999). PIER (2013) describes the species’ habitats in Hawaii, Fiji, Niue and Chile; moisture, exposure to the sun and open sites seem to be common features.

Properties

(Section from Purwaningsih and Brink, 1999)
Sweet fennel fruits smell strongly of anise and have a penetrating and sweet taste, whereas those of bitter or common fennel have a pungent odour and taste like camphor. Fennel 'seed' contains per 100 g edible portion: water 8.8 g, protein 15.8 g, fat 14.9 g, carbohydrates 36.6 g, fibre 15.7 g, ash 8.2 g (Ca 1.2 g, Fe 19 mg, Mg 385 mg, P 487 mg, K 1.7 g, Na 88 mg, Zn 4 mg), vitamin A 135 IU, niacin 6 mg, thiamine 0.41 mg and riboflavin 0.35 mg. The energy value is about 1440 kJ/100 g. The lipid fraction contains 9.9 g total monounsaturated and 1.7 g total polyunsaturated fatty acids. The fixed oil is mainly composed of petroselinic acid (60-75%), oleic acid and linoleic acid. The fruits also contain flavonoids and stigmasterol. The 1000-seed weight is 4-8 g.

The essential oil is present in secretory channels in most parts of the plant, but in mature fennel about 95% of the oil is located in the fruit. The essential oil yield after hydrodistillation of the fruits is 1.9-3.1%. The oil obtained from sweet fennel possesses a finer odour and flavour than that from bitter fennel. The major compound of sweet fennel oil is (E)-anethole (up to 70-80%), which is responsible for the anise fragrance and sweet taste. The (E)-anethole content of sweet fennel oil is only half that of sweet fennel, whereas the fenchone content is higher. Fenchone is considered a character-impact constituent of sweet fennel oil.

The concentration of major compounds of the essential oil varies with plant part and development stage. In bitter fennel populations from different origins it was found that the anethole and fenchone concentrations were higher in the waxy and ripe fruits than in the stems and leaves, whereas the α-pinene concentration showed an opposite trend. Furthermore, the anethole and fenchone concentrations increased from the bud stage until fruit ripening, whereas the α-pinene and limonene concentrations decreased. The estragole concentration varied only slightly. The composition of essential oil from the roots is very different from that from the rest of the plant, with terpinolene, myristicin and apiole being the main compounds. The residue after essential oil distillation from fennel fruits contains 14-22 % protein and 12-18.5% fat.

Wild fennel

Seeds germinate at almost any time of the year but plants do not flower until they are 18 months to 2 years old.  Flowering stems grow afresh each spring from the perennial crowns of established plants. In Australia, flowering begins in November and continues through the summer. Seeds are produced in summer and autumn, and the flowering stems brown off and partly die back in winter. In late winter or spring new leaves form on the lower stems and the crown (Parsons and Cuthbertson, 1992).

Climate

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ClimateStatusDescriptionRemark
Cf - Warm temperate climate, wet all year Tolerated 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
Af - Tropical rainforest climate Tolerated > 60mm precipitation per month
BS - Steppe climate Tolerated > 430mm and < 860mm annual precipitation
Ds - Continental climate with dry summer Tolerated Continental climate with dry summer (Warm average temp. > 10°C, coldest month < 0°C, dry summers)

Air Temperature

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Parameter Lower limit Upper limit
Mean annual temperature (ºC) 6 24

Rainfall

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ParameterLower limitUpper limitDescription
Mean annual rainfall5004000mm; lower/upper limits

Soil Tolerances

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Soil drainage

  • free

Soil reaction

  • alkaline
  • neutral

Soil texture

  • light
  • medium

Notes on Natural Enemies

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Very many natural enemies of cultivated crops of F. vulgare are listed in the literature; they include insects, nematodes, molluscs, fungi, bacteria and parasitic plants. However, there is little information on how many of these affect populations of wild forms of the species, although presumably many of them can.

Means of Movement and Dispersal

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Natural Dispersal (Non-Biotic)

It is possible that the seeds are dispersed by water. Seeds of this species are small and prolific, and the species can grow along riverbeds and is known to escape into coastal areas (Webb et al., 1988; Cal-IPC, 2015; Peru Checklist, 2015).

Vector Transmission (Biotic)

In Australia, and probably elsewhere, the seeds of F. vulgare contaminate agricultural produce, vehicles, machinery, wool and skin of animals, clothing, gravel, mud and water (Parsons and Cuthbertson, 1992). Presumably when livestock (especially thick-fleeced sheep) push through thickets of fruiting plants some of the seeds are dislodged from the plants and fall onto and become entangled in their fleeces. The seeds are eaten by rodents and birds, while feral pigs eat its roots (DiTomaso et al., 2013; Cal-IPC, 2015). In the Channel Islands National Park off the coast of California F. vulgare was apparently introduced in the 1800’s and has become a problematic weed after its seed was spread by animals (US National Park Service, 2015).

Accidental Introduction

Although agricultural and horticultural seeds may be contaminated with those of F. vulgare, in commercial consignments this should be noticed by phytosanitary inspectors following the appropriate regulations. There is however some danger of accidental introduction of seeds (or pieces of crown or root -- Parsons and Cuthbertson, 1992) to new places on agricultural or other machinery, or in mud, gravel or agricultural produce.

Intentional Introduction

Migrants to new countries always take with them something to remind them of their old homes and a few seeds of a favourite flavouring plant would seem sensible.  Intentional introduction is almost certainly how F. vulgare has become established in many countries already and its spread to yet more countries where conditions are favourable for its growth is to be expected.

There is considerable international trade in fennel seeds (Purwaningsih and Brink, 1999).

Pathway Causes

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CauseNotesLong DistanceLocalReferences
Crop productionSpice and medicinal plant Yes Yes
Digestion and excretionSeeds are small and eaten by rodents and birds Yes Cal-IPC, 2015
Escape from confinement or garden escape Yes Yes Randall, 2012
Medicinal use Yes Yes

Pathway Vectors

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VectorNotesLong DistanceLocalReferences
Clothing, footwear and possessions Yes
Livestock Yes
Machinery and equipment Yes
Water Yes

Impact Summary

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

Economic Impact

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F. vulgare rarely invades established pastures or regularly cultivated land (Parsons and Cuthbertson, 1992). Although livestock are probably reluctant to eat well developed plants because of the taste, small plants are probably eaten and destroyed by grazing or treading or both. In addition a well-maintained pasture tends to resist invasion by new seedlings.

According to Parsons and Cuthbertson (1992) toxicity problems with grazing animals are not encountered, but deaths of both sheep and cattle have occurred in Tasmania when trash left after distillation of commercially grown fennel was fed to animals (Connor, 1977).

The costs of controlling F. vulgare where it grows in and around railway yards, on roadsides, in industrial areas and in yards where machinery is stored must be considerable whether this is done by machine or by herbicide application.

Environmental Impact

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Once firmly established, F. vulgare excludes all other vegetation, and apparently tomatoes and beans do not grow in its company, suggesting an allelopathic effect (Parsons and Cuthbertson, 1992).

In California, F. vulgare is classified as one of the most invasive wildland pest plants and is documented as an aggressive invader that displaces natives and disrupts natural habitats (CAL-IPC, 2005).  The same source points out that once established it excludes almost all other vegetation, and that soil disturbance encourages it. Furthermore it can alter fire regimes when dry because, once ignited, it creates an intense, fast-moving fire. In California it mainly invades gaps in coastal scrub, where besides causing a fire hazard it shades the understorey herbaceous layer.

The University of Queensland (2013) describes F. vulgare as ‘a significant and widespread  environmental weed’, especially in south-eastern Australia (Tasmania, Australian Capital Territory, South Australia, New South Wales), but also in Western Australia and the cooler districts of south-eastern Queensland. It is probably of most concern in Victoria. It is able to outcompete small native understorey shrubs and groundcover plants and is likely to reduce the amount of useful habitat available to native animals. It is especially important along waterways and wetlands but can also affect remnant vegetation in farming areas. It has invaded many conservation areas in south-eastern Australia and probably threatens the last remaining population of the critically endangered sunshine diuris (Diuris fragrantissima).

In New Zealand F. vulgare was reported by Esler (1988) as growing abundantly on roadsides, railway margins, industrial sites and other waste land. He adds that if left unchecked it becomes dominant, and says that part of its competitive success comes from the vigorous rosette on a perennial rootstock, and the shading of other plants from the previous year’s growth, which also creates a fire hazard. It has been considered a problem in New Zealand for over a century, as it was included in the second and third schedules of the Noxious Weeds Act of 1904 (Thomson, 1922).

If long-residual herbicides like diuron or bromacil are used to control F. vulgare, they can sometimes leach into waterways and cause damage to desirable vegetation downstream (Young, 2012).

Threatened Species

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Threatened SpeciesConservation StatusWhere ThreatenedMechanismReferencesNotes
Diuris fragrantissimaNational list(s) National list(s)Competition - monopolizing resourcesUniversity of Queensland, 2013

Social Impact

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Although the leaves and seeds of F. vulgare are used throughout the world as flavouring and for their medicinal properties, plants can sometimes cause adverse effects in mammals. The US Food and Drug Administration (2008) says that the fennels are ‘generally recognized as safe for their intended use’ but also carries reports of seed consumption causing asthma, oestrogenic activity in mice (Malini et al., 1985), and mutagenic activity; these probably occurred when high levels of seeds or extracts were fed.

F. vulgare is among the species of Apiaceae listed by Connor (1977) as causing dermatitis if people handle or touch the plants and are then exposed to sunlight.

Plants for a Future (2013) also warns ‘Skin contact with the sap or essential oil is said to cause photo-sensitivity and/or dermatitis in some people. Ingestion of the oil can cause vomiting, seizures and pulmonary oedema’, citing Foster and Duke (1990). Quoting Karalliedde and Gawarammana (2008), Plants for a Future (2013) also says ‘Avoid for small children. Avoid if cirrhosis/liver disorders.’

Risk and Impact Factors

Top of page Invasiveness
  • Proved invasive outside its native range
  • Highly adaptable to different environments
  • Pioneering in disturbed areas
  • Benefits from human association (i.e. it is a human commensal)
  • Long lived
  • Fast growing
  • Has high reproductive potential
  • Gregarious
  • Has propagules that can remain viable for more than one year
Impact outcomes
  • Damaged ecosystem services
  • Ecosystem change/ habitat alteration
  • Modification of fire regime
  • Monoculture formation
  • Reduced native biodiversity
  • Threat to/ loss of endangered species
  • Threat to/ loss of native species
Impact mechanisms
  • Competition - monopolizing resources
  • Competition - shading
  • Competition - smothering
Likelihood of entry/control
  • Highly likely to be transported internationally accidentally
  • Highly likely to be transported internationally deliberately
  • Difficult to identify/detect as a commodity contaminant

Uses

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Economic Value

F. vulgare subsp. vulgare var. azoricum is commercially grown for its swollen leaf bases and edible leaves which can be eaten raw or cooked as a vegetable. The other two varieties (dulce and vulgare) are commercially grown for their fruits (‘seeds’) and vegetative parts. A reddish-leaved form called bronze fennel is often grown in gardens mainly as an ornamental, and is known as F. vulgare ‘Purpureum’ or F. vulgare var. rubrum.

Fennel has been grown in parts of Europe for human consumption for thousands of years. The leaf bases are eaten raw or cooked as a vegetable; chopped leaves are used to garnish salads, stews and soups; the roots are cooked as a vegetable; the aromatic fruits (known in the trade as ‘seeds’) are used as culinary spice to flavour bread, stews and many other foods and dishes; and whole leaves are used in preparing meat dishes and enhance the flavour of fish. Ground fennel fruit is often a constituent of curry powder. Several sweet, common or bitter cultivars are grown commercially in many countries for the production of anethol, used as a flavouring in foods, cordials and liqueurs like absinthe (Parsons and Cuthbertson, 1992; Purwaningsih and Brink, 1999).

All plant parts contain essential oil, which is used for flavouring, in detergents, and in cosmetics such as soaps, creams, lotions and luxury perfumes. Sweet fennel oil is extensively applied in food products, including alcoholic and non-alcoholic beverages, desserts, candies, baked goods, meat and meat products, condiments and relishes. The maximum permitted level in food products is about 0.3%. Bitter and sweet fennel oils are applied in perfumery, with maximum permitted levels of 0.4%. Sweet fennel oil is used to a limited extent and mainly in cosmetics. Anethole obtained from sweet fennel is applied as a flavouring agent and in the pharmaceutical and perfume industries, but anethole from cheaper sources is usually available. The fruit residue after essential oil distillation may be fed to cattle. In the USA the regulatory status 'generally recognized as safe' has been accorded to common or bitter fennel (GRAS 2481), sweet fennel (GRAS 2482) and sweet fennel oil (GRAS 2483) (Purwaningsih and Brink, 1999).

Social Benefit

The medicinal use of fennel also dates from ancient times. It was mentioned by Hippocrates and Dioscorides as a diuretic and as stimulating blood flow in the pelvic area and uterus, and has been used as a main ingredient in the Arab and Ayurvedic medicinal systems. The fruits are widely known as a stimulant, stomachic, expectorant and carminative, and are officinal in many pharmacopoeias. The roots are traditionally applied as a diuretic and purgative. In Indonesia, the fruit is traditionally used in combination with the bark of Alyxia species to give an agreeable flavour to medicines, but the combination is also believed to be useful in the treatment of sprue (coeliac disease). In India, the leaves are considered diuretic, fruit juice is administered to improve eyesight, and hot infusions of the fruits are applied to increase milk secretion and to stimulate sweating. In Chinese herbal medicine, fennel is used against gastroenteritis, hernia, indigestion and abdominal pain, to resolve phlegm and to stimulate milk production. In modern western medicine, fennel and fennel oil are administered as carminative or flavouring agents in certain laxatives. In Germany, the fruits are used in phytomedicine against dyspeptic disorders, as a gastrointestinal antispasmodic, as an expectorant and in syrups against children's coughs (Purwaningsih and Brink, 1999).

In ancient times fennel was credited with magical properties. Prometheus was thought to have brought the fire of the sun from heaven to humans in a hollowed fennel stem. Pliny declared that fennel enabled the eye to perceive the beauty of nature with clarity (Parsons and Cuthbertson, 1992).

The ground spice and the essential oil have antioxidant properties; the essential oil also has antifungal and antibacterial activity, and antiviral activity against Potato virus X, Tobacco mosaic virus and Tobacco ringspot virus. It also shows spasmolytic effects on smooth muscle of experimental animals. Monographs on the physiological properties of sweet fennel oil and bitter fennel oil have been published by the Research Institute for Fragrance Materials (RIFM) (Purwaningsih and Brink, 1999).

As for individual compounds, anethole is effective against Staphylococcus aureus, Escherichia coli, Candida albicans and Corynebacterium sp., and has stimulant and carminative properties. Furthermore, it is allergenic and weakly insecticidal. Long-term studies have shown that it is not carcinogenic. The oestrogenic activity (e.g., increasing milk secretion and promoting menstruation) of fennel is probably due to polymers of anethole, such as dianethole and photanetholes. Estragole is a hepatic carcinogen in mice. In experiments with rats, limonene limited mammary tumour growth (Purwaningsih and Brink, 1999).

Environmental Services

Plants for a Future (2013), citing Bown (1995), says that flowering fennel attracts beneficial insects such as bees, parasitic wasps, tachinid flies and hoverflies to the garden.

Adulterations and Substitutes

Commercial spice samples are sometimes adulterated with sand, stem tissue, fruit residues left after distillation, immature or mouldy fruits or other umbelliferous fruits. Fennel fruits and those of anise (Pimpinella anisum) are often confused and substituted for each other.

Anethole-rich oil is also obtained from P. anisum and star anise (Illicium verum). The cultivation of fennel as a source of anethole was developed in Europe to reduce the dependence on anethole obtained from star anise in Asian countries. Anethole can also be produced chemically, either by hemisynthesis from estragole (e.g., extracted from pine oil) or by complete synthesis. However, in some countries the use of synthetic anethole for food products is prohibited by law.

Uses List

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Human food and beverage

  • Food additive
  • Leaves (for beverage)
  • Seeds
  • Spices and culinary herbs
  • Vegetable

Materials

  • Cosmetics
  • Essential oils

Medicinal, pharmaceutical

  • Source of medicine/pharmaceutical
  • Traditional/folklore

Similarities to Other Species/Conditions

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The University of Queensland (2013) lists a number of other species from the same family (Apiaceae) which are sometimes confused with F. vulgare, including Berula erecta, Conium maculatum, Ammi majus, Coriandrum sativum, Daucus carota, and Apium graveolensPurwaningsih and Brink (1999) also say that this species is often confused with dill (Anethum graveolens); the two species are closely related and easily cross. Fennel and dill can be distinguished by their odour (fennel smells like liquorice, dill smells bitter and slightly pungent) and their ripe fruits (fennel has wingless fruits, dill fruits have a wide wing). Fennel plants without fruits may be recognised by their finely dotted stems, the longer and broader leaf sheaths and the usually shorter secondary rays in the umbel.

Prevention and Control

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Movement Control

The importation and sale of the species are prohibited in Tasmania (University of Queensland, 2013).

Physical/Mechanical Control

Seedlings and smaller plants can be dug out, but crowns and taproots must be removed to prevent regrowth (PIER, 2013). DiTomaso et al. (2013) say that slashing just before flowering may kill the plants, although repeat slashing of regrowth may be needed.

Chemical Control

Because the species spreads its roots quickly and creates dense mats that are difficult to physically remove, chemical control is usually necessary once the species is established. Effective herbicides for control of F. vulgare include glyphosate, triclopyr and 2,4-D ester (Weber, 2003). Long-residual herbicides like diuron or bromacil are also used (Young, 2012). Bell et al. (2008) evaluated the impacts of glyphosate and triclopyr applied alone and in combination in natural habitats in California, and also tested spot spraying versus broadcast treatments. They found that glyphosate and triclopyr alone could give very good (but not complete) control of plants for up to a year after application, and that combinations of the two were also effective except when applied at too low a rate or if some plants in the treated area were not contacted by the herbicide. Broadcast spraying was more economical in terms of herbicide use, and spot spraying missed some plants. Also in California (Santa Cruz Island), Brenton and Klinger (2002) report that spraying in the wet season (February-early March) had most effect in reducing cover of fennel. In this study, trichlopyr was effective in reducing F. vulgare, but it is suggested that other restoration techniques may be necessary to enhance habitat for native species following removal of F. vulgare. Power et al. (2014) report that seeding with native seed is a critical step in vegetation restoration on Santa Cruz Island following F. vulgare control.

Pisanu and Mooney (2008) found triclopyr to be the preferred chemical for F. vulgare control on roadsides of Kangaroo Island, South Australia.

Grazing

After removal of large numbers of sheep and cattle from Santa Cruz Island off the Californian coast in the mid-1990s, many of the island’s vegetation communities became dominated by F. vulgare (Erskine Ogden and Rejmánek, 2005). Presumably before livestock were removed their grazing kept the plants under control.

Ecosystem Restoration

Erskine Ogden and Rejmánek (2005) tested the efficacy of different control methods on the control of F. vulgare and the effect of management on the recovery of native species on Santa Cruz Island off the coast of California. Experimental plots were burned and then sprayed from the air with triclopyr plus surfactant. Fennel cover decreased significantly from about 60% average cover to less than 3% cover, but the expected increase in native species cover and richness did not occur. Instead fennel plots were replaced by Mediterranean annual grasses such as Avena spp., Bromus hordeaceus, Lolium multiflorum, Hordeum murinum and Bromus diandrus – species that now dominate many Californian landscapes. Surprisingly, though, fennel cover also declined significantly in untreated plots, from 60% cover to just under 40%, while native species richness increased significantly, possibly as a result of the greater vertical complexity of fennel communities, which increased visits by frugivorous birds and may have therefore increased dispersal of seeds of native species.

Gaps in Knowledge/Research Needs

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Further research is recommended on improving prevention and control methods, as the species is highly invasive yet will continue to be cultivated for its popularity as a spice plant.

Bibliography

Top of page Bernáth J, Németh E, Kattaa A, Héthelyi E, 1996. Morphological and chemical evaluation of fennel (Foeniculum vulgare Mill.) populations of different origin. Journal of Essential Oil Research, 8(3):247-253.

Boelens MH, 1991. Spices and condiments II. In: Maarse H (Ed). Volatile compounds in foods and beverages. New York, USA: Marcel Dekker, 449-482.

Buntain M, Chung B, 1994. Effects of irrigation and nitrogen on the yield components of fennel (Foeniculum vulgare Mill.). Australian Journal of Experimental Agriculture, 34(6):845-849.

Földesi D, Hornok L, 1992. Fennel (Foeniculum vulgare Mill.). In: Hornok L (Ed). Cultivation and processing of medicinal plants. Chichester, UK: John Wiley & Sons, 162-166.

Hunault G, Desmarest P, du Manoir J, 1989. Foeniculum vulgare Miller: cell culture, regeneration and the production of anethole. In: Bajaj YPS, ed. Biotechnology in agriculture and forestry. Vol. 7. Medicinal and aromatic plants 2. Berlin, Germany: Springer Verlag, 185-212.

Husain A, 1994. Essential oil plants and their cultivation. Central Institute of Medicinal and Aromatic Plants, Lucknow, India, 240-245.

Leung AY, Foster S,1996. Encyclopedia of common natural ingredients used in food, drugs and cosmetics. 2nd edition. New York, US: John Wiley & Sons, 240-243.

Peterson LE, Clark RJ, Menary RC, 1993. Umbel initiation and stem elongation in fennel (Foeniculum vulgare) initiated by photoperiod. Journal of Essential Oil Research, 5:37-43.

References

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Balick MJ, 2014. Rodale's 21st-century herbal: A practical guide for healthy living using nature's most powerful plants. New York, NY: Rodale. 498 pp. https://books.google.com/books?id=ycdWAwAAQBAJ&printsec=frontcover#v=onepage&q&f=false

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Cal-IPC, 2015. California Invasive Plant Council- Foeniculum vulgare. Berkeley CA, USA: California Invasive Plant Council. http://www.cal-ipc.org/ip/management/plant_profiles/Foeniculum_vulgare.php

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Erskine Ogden JA, Rejmánek M, 2005. Recovery of native plant communities after the control of a dominant invasive plant species, Foeniculum vulgare: implications for management. Biological Conservation, 125(4):427-439. http://www.sciencedirect.com/science/journal/00063207

Esler AE, 1988. Naturalisation of plants in urban Auckland. Wellington, New Zealand: DSIR Publishing

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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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17/03/15: Updated by:

Marianne Jennifer Datiles, Department of Botany-Smithsonian NMNH, Washington DC, USA

22/06/13: Updated by:

Ian Popay, consultant, New Zealand, with the support of Landcare Research.

Distribution Maps

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