Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Datasheet

Melilotus officinalis
(yellow sweet clover)

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Datasheet

Melilotus officinalis (yellow sweet clover)

Summary

  • Last modified
  • 20 November 2018
  • Datasheet Type(s)
  • Invasive Species
  • Host Plant
  • Preferred Scientific Name
  • Melilotus officinalis
  • Preferred Common Name
  • yellow sweet clover
  • Taxonomic Tree
  • Domain: Eukaryota
  •   Kingdom: Plantae
  •     Phylum: Spermatophyta
  •       Subphylum: Angiospermae
  •         Class: Dicotyledonae
  • Summary of Invasiveness
  • Melilotus officinalis is a herbaceous legume species, native to parts of Asia and possibly Europe (sources differ on this), that has been extensively introduced to be used as a forage and nitrogen-fixing crop....

  • Principal Source
  • Draft datasheet under review

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Pictures

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PictureTitleCaptionCopyright
Melilotus officinalis (yellow sweet clover); flowering habit. Sweetclover in this area is essentially an inhabitant of disturbance-prone settings. Butte County, Idaho, USA. June 2010.
TitleFlowering habit
CaptionMelilotus officinalis (yellow sweet clover); flowering habit. Sweetclover in this area is essentially an inhabitant of disturbance-prone settings. Butte County, Idaho, USA. June 2010.
Copyright©Prof Matt Lavin-2010/Bozeman, Montana, USA - CC BY-SA 2.0
Melilotus officinalis (yellow sweet clover); flowering habit. Sweetclover in this area is essentially an inhabitant of disturbance-prone settings. Butte County, Idaho, USA. June 2010.
Flowering habitMelilotus officinalis (yellow sweet clover); flowering habit. Sweetclover in this area is essentially an inhabitant of disturbance-prone settings. Butte County, Idaho, USA. June 2010.©Prof Matt Lavin-2010/Bozeman, Montana, USA - CC BY-SA 2.0
Melilotus officinalis (yellow sweet clover); flowering habit. Fresnes-au-Mont, Meuse, France. June 2007.
TitleFlowering habit
CaptionMelilotus officinalis (yellow sweet clover); flowering habit. Fresnes-au-Mont, Meuse, France. June 2007.
Copyright©Olivier Pichard/via wikipedia - CC BY-SA 3.0
Melilotus officinalis (yellow sweet clover); flowering habit. Fresnes-au-Mont, Meuse, France. June 2007.
Flowering habitMelilotus officinalis (yellow sweet clover); flowering habit. Fresnes-au-Mont, Meuse, France. June 2007.©Olivier Pichard/via wikipedia - CC BY-SA 3.0
Melilotus officinalis (yellow sweet clover); flowering habit. Glogów, SW Poland. June 2015.
TitleFlowering habit
CaptionMelilotus officinalis (yellow sweet clover); flowering habit. Glogów, SW Poland. June 2015.
Copyright©Krzysztof Ziarnek-2015/via wikipedia - CC BY-SA 4.0
Melilotus officinalis (yellow sweet clover); flowering habit. Glogów, SW Poland. June 2015.
Flowering habitMelilotus officinalis (yellow sweet clover); flowering habit. Glogów, SW Poland. June 2015.©Krzysztof Ziarnek-2015/via wikipedia - CC BY-SA 4.0
Melilotus officinalis (yellow sweet clover); flowers. Bruchmühlbach-Miesau, Germany. June 2016.
TitleFlowers
CaptionMelilotus officinalis (yellow sweet clover); flowers. Bruchmühlbach-Miesau, Germany. June 2016.
CopyrightPublic Domain - Released by AnRo0002/via wikipedia - CC0
Melilotus officinalis (yellow sweet clover); flowers. Bruchmühlbach-Miesau, Germany. June 2016.
FlowersMelilotus officinalis (yellow sweet clover); flowers. Bruchmühlbach-Miesau, Germany. June 2016.Public Domain - Released by AnRo0002/via wikipedia - CC0
Melilotus officinalis (yellow sweet clover); flower spike. Austria. June 2012.
TitleFlower spike
CaptionMelilotus officinalis (yellow sweet clover); flower spike. Austria. June 2012.
Copyright©Gernot Molitor (Radio Tonreg)/via wikipedia - CC BY 2.0
Melilotus officinalis (yellow sweet clover); flower spike. Austria. June 2012.
Flower spikeMelilotus officinalis (yellow sweet clover); flower spike. Austria. June 2012.©Gernot Molitor (Radio Tonreg)/via wikipedia - CC BY 2.0
Melilotus officinalis (yellow sweet clover); leaves. The green glabrate succulent leaflets of Melilotus are distinct from the thin textured, dark green and hairly ones of Medicago. Butte County, Idaho, USA. June 2010.
TitleLeaves
CaptionMelilotus officinalis (yellow sweet clover); leaves. The green glabrate succulent leaflets of Melilotus are distinct from the thin textured, dark green and hairly ones of Medicago. Butte County, Idaho, USA. June 2010.
Copyright©Prof Matt Lavin-2010/Bozeman, Montana, USA - CC BY-SA 2.0
Melilotus officinalis (yellow sweet clover); leaves. The green glabrate succulent leaflets of Melilotus are distinct from the thin textured, dark green and hairly ones of Medicago. Butte County, Idaho, USA. June 2010.
LeavesMelilotus officinalis (yellow sweet clover); leaves. The green glabrate succulent leaflets of Melilotus are distinct from the thin textured, dark green and hairly ones of Medicago. Butte County, Idaho, USA. June 2010.©Prof Matt Lavin-2010/Bozeman, Montana, USA - CC BY-SA 2.0

Identity

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Preferred Scientific Name

  • Melilotus officinalis (L.) Pall.

Preferred Common Name

  • yellow sweet clover

Other Scientific Names

  • Medicago officinalis (L.) E.H.L.Krause
  • Melilotus arenarius Grecescu
  • Melilotus arvensis Wallr.
  • Melilotus melilotus-officinalis Asch. & Graebn.
  • Melilotus neglectus Ser.
  • Melilotus petitpierreanus Willd.
  • Trifolium melilotus officinalis L.
  • Trifolium officinale L.

International Common Names

  • English: common melilot; field melilot ; ribbed melilot; yellow melilot; yellow sweetclover; yellow sweet-clover; yellow trefoil
  • Spanish: cornilla real; meliloto amarillo; meliloto de los campos; trébol de olor; trebol de olor amarillo
  • French: melilot des champs; melilot jaune; melilot officinal
  • Chinese: cao mu xi

Local Common Names

  • Canada: Yellow sweet clover
  • Cuba: Torongil For
  • Dominican Republic: Trebol de arbol; trebol de arbol blanco
  • Germany: Acker- Honigklee; Echter Steinklee; gelber Steinklee
  • Italy: meliloto giallo
  • Japan: seiyō-ebira-hagi
  • Netherlands: Akkerhoningklaver
  • Portugal: trevo-cheiroso
  • Sweden: Gulmelot

EPPO code

  • MEUOF (Melilotus officinalis)

Summary of Invasiveness

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Melilotus officinalis is a herbaceous legume species, native to parts of Asia and possibly Europe (sources differ on this), that has been extensively introduced to be used as a forage and nitrogen-fixing crop. It has escaped from cultivation and become an invasive weed in many temperate and tropical regions; it can also be toxic to livestock.  It is a prolific seeder, and its seeds can remain viable in the soil for many years. It is fast-growing and can grow in a wide range of environmental conditions. Like other nitrogen-fixing legumes, M. officinalis has the potential to alter soil conditions and nutrient cycling. It is allelopathic and so forms dense monospecific stands that displace and inhibit the establishment of native vegetation. In North America, infestations reduce the occurrence of natural fires and degrade native grassland communities that depend on frequent fires.  In Alaska and Canada, this species is a serious problem on waterways because it is invading glacial river floodplains.  Currently, it is recognized as a conservation problem in North America because it is invading critical natural areas such as national parks and protected lands.

Taxonomic Tree

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  • Domain: Eukaryota
  •     Kingdom: Plantae
  •         Phylum: Spermatophyta
  •             Subphylum: Angiospermae
  •                 Class: Dicotyledonae
  •                     Order: Fabales
  •                         Family: Fabaceae
  •                             Subfamily: Papilionoideae
  •                                 Genus: Melilotus
  •                                     Species: Melilotus officinalis

Notes on Taxonomy and Nomenclature

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The Fabaceae are one of the largest families of flowering plants.  This family includes about 745 genera and 19,500 species growing in a great variety of climates and habitats (Stevens, 2012).  Melilotus is a small genus of Fabaceae, comprising 22 species of annual, biennial and perennial herbs originally from Europe and Asia, but now found worldwide (The Plant List, 2013). Many members of the genus are common weeds of grasslands and cultivated lands (USDA-NRCS, 2017).

Description

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Annual, biennial or short-lived perennial herbs, sparsely puberulent to glabrescent. Stems erect, 40-100(-250) cm, longitudinally ridged. Stipules linear-falcate, 3-5(-7) mm, entire or with 1 tooth at base; petiole slender; leaflets obovate, broadly ovate, oblanceolate, to linear, 15-25 (-30) × 5-15 mm, lateral veins running into teeth, 8-12 pairs, margins shallowly serrate. Racemes 6-15 (-20) mm, 30-70-flowered, dense at first, becoming lax in anthesis; bracts equal to pedicels, 1.5-2 mm. Corolla yellow, 4.5-7 mm; standard ± equal to wings and keel. Ovary narrowly ovate; ovules 4-8. Legume ovoid, 3-5 × 2 mm, veins transversely reticulate, dark brown, apex with persistent style. Seeds 1 or 2, yellowish brown, smooth, ovoid, 2.5 mm (Flora of China, 2017).

Plant Type

Top of page Annual
Biennial
Broadleaved
Herbaceous
Perennial
Seed propagated

Distribution

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The native distribution range of M. officinalis is still unclear. While some authors consider it to be native to Europe and Asia (USDA-ARS, 2017), others consider it native to Asia and introduced elsewhere (DAISIE, 2018). It has been widely introduced and can currently be found naturalized across Europe, Asia, Africa, the Americas, the West Indies, Australia and New Zealand (DAISIE, 2017; ILDIS, 2017; USDA-NRSC, 2017; USDA-ARS, 2017).

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, 2017
ArmeniaPresentNativeUSDA-ARS, 2017
AzerbaijanPresentNativeUSDA-ARS, 2017
ChinaPresent Invasive Chen et al., 2013; USDA-ARS, 2017
Georgia (Republic of)PresentNativeUSDA-ARS, 2017
IndiaPresentNativeUSDA-ARS, 2017
-Himachal PradeshPresentNativeUSDA-ARS, 2017
-Jammu and KashmirPresentNativeUSDA-ARS, 2017
IranPresentNativeUSDA-ARS, 2017
IraqPresentNativeUSDA-ARS, 2017
JapanPresentIntroducedUSDA-ARS, 2017Naturalized
KazakhstanPresentNativeUSDA-ARS, 2017
KyrgyzstanPresentNativeUSDA-ARS, 2017
LebanonPresentIntroducedUSDA-ARS, 2017Naturalized
PakistanPresentNativeUSDA-ARS, 2017
TajikistanPresentNativeUSDA-ARS, 2017
TurkeyPresentNativeUSDA-ARS, 2017
TurkmenistanPresentNativeUSDA-ARS, 2017
UzbekistanPresentNativeUSDA-ARS, 2017

Africa

KenyaPresentIntroducedUSDA-ARS, 2017Naturalized
MoroccoPresentIntroducedUSDA-ARS, 2017Naturalized
South AfricaPresentIntroducedUSDA-ARS, 2017Naturalized

North America

CanadaPresentIntroducedPresent based on regional distribution
-AlbertaPresentIntroducedUSDA-NRCS, 2017
-British ColumbiaPresentIntroduced Invasive USDA-NRCS, 2017
-ManitobaPresentIntroducedUSDA-NRCS, 2017
-New BrunswickPresentIntroducedUSDA-NRCS, 2017
-Newfoundland and LabradorPresentIntroducedUSDA-NRCS, 2017
-Northwest TerritoriesPresentIntroducedUSDA-NRCS, 2017
-Nova ScotiaPresentIntroducedUSDA-NRCS, 2017
-OntarioPresentIntroducedUSDA-NRCS, 2017
-Prince Edward IslandPresentIntroducedUSDA-NRCS, 2017
-QuebecPresentIntroducedUSDA-NRCS, 2017
-SaskatchewanPresentIntroducedUSDA-NRCS, 2017
-Yukon TerritoryPresentIntroduced Invasive YISC, undated
GreenlandPresentIntroducedUSDA-NRCS, 2017
MexicoPresentIntroducedILDIS, 2017
USAPresentPresent based on regional distribution
-AlabamaPresentIntroducedUSDA-NRCS, 2017
-AlaskaPresentIntroduced Invasive USDA-NRCS, 2017
-ArizonaPresentIntroducedUSDA-NRCS, 2017
-ArkansasPresentIntroducedUSDA-NRCS, 2017
-CaliforniaPresentIntroducedUSDA-NRCS, 2017
-ColoradoPresentIntroduced Invasive USDA-NRCS, 2017
-ConnecticutPresentIntroducedUSDA-NRCS, 2017
-DelawarePresentIntroducedUSDA-NRCS, 2017
-District of ColumbiaPresentIntroducedUSDA-NRCS, 2017
-FloridaPresentIntroducedUSDA-NRCS, 2017
-GeorgiaPresentIntroducedUSDA-NRCS, 2017
-HawaiiPresentIntroducedUSDA-NRCS, 2017
-IdahoPresentIntroducedUSDA-NRCS, 2017
-IllinoisPresentIntroduced Invasive USDA-NRCS, 2017Noxious weed
-IndianaPresentIntroducedUSDA-NRCS, 2017
-IowaPresentIntroduced Invasive USDA-NRCS, 2017
-KansasPresentIntroduced Invasive USDA-NRCS, 2017
-KentuckyPresentIntroduced Invasive USDA-NRCS, 2017Noxious weed
-LouisianaPresentIntroducedUSDA-NRCS, 2017
-MainePresentIntroducedUSDA-NRCS, 2017
-MarylandPresentIntroducedUSDA-NRCS, 2017
-MassachusettsPresentIntroducedUSDA-NRCS, 2017
-MichiganPresentIntroducedUSDA-NRCS, 2017
-MinnesotaPresentIntroduced Invasive USDA-NRCS, 2017
-MississippiPresentIntroducedUSDA-NRCS, 2017
-MissouriPresentIntroducedUSDA-NRCS, 2017
-MontanaPresentIntroduced Invasive USDA-NRCS, 2017
-NebraskaPresentIntroduced Invasive USDA-NRCS, 2017Noxious weed
-NevadaPresentIntroducedUSDA-NRCS, 2017
-New HampshirePresentIntroducedUSDA-NRCS, 2017
-New JerseyPresentIntroducedUSDA-NRCS, 2017
-New MexicoPresentIntroduced Invasive USDA-NRCS, 2017
-New YorkPresentIntroducedUSDA-NRCS, 2017
-North CarolinaPresentIntroducedUSDA-NRCS, 2017
-North DakotaPresentIntroduced Invasive USDA-NRCS, 2017
-OhioPresentIntroducedUSDA-NRCS, 2017
-OklahomaPresentIntroduced Invasive USDA-NRCS, 2017
-OregonPresentIntroducedUSDA-NRCS, 2017
-PennsylvaniaPresentIntroducedUSDA-NRCS, 2017
-Rhode IslandPresentIntroducedUSDA-NRCS, 2017
-South CarolinaPresentIntroducedUSDA-NRCS, 2017
-South DakotaPresentIntroduced Invasive USDA-NRCS, 2017
-TennesseePresentIntroduced Invasive USDA-NRCS, 2017Noxious weed
-TexasPresentIntroducedUSDA-NRCS, 2017
-UtahPresentIntroducedUSDA-NRCS, 2017
-VermontPresentIntroducedUSDA-NRCS, 2017
-VirginiaPresentIntroducedUSDA-NRCS, 2017
-WashingtonPresentIntroducedUSDA-NRCS, 2017
-West VirginiaPresentIntroducedUSDA-NRCS, 2017
-WisconsinPresentIntroduced Invasive USDA-NRCS, 2017Noxious weed
-WyomingPresentIntroduced Invasive USDA-NRCS, 2017Noxious weed

Central America and Caribbean

CubaPresentIntroducedAcevedo and Strong, 2012
Dominican RepublicPresentIntroduced Invasive Mir, 2012Listed as M. alba

South America

ArgentinaPresentIntroduced Invasive IABIN, 2017
BoliviaPresentIntroducedMissouri Botanical Garden, 2017
ChilePresentIntroducedUSDA-ARS, 2017Naturalized
ParaguayPresentIntroduced Invasive IABIN, 2017
UruguayPresentIntroducedUSDA-ARS, 2017Naturalized

Europe

AlbaniaPresentNativeUSDA-ARS, 2017
AustriaPresentNativeUSDA-ARS, 2017
BelarusPresentNativeUSDA-ARS, 2017
BelgiumPresentDAISIE, 2017; USDA-ARS, 2017
BulgariaPresentDAISIE, 2017; USDA-ARS, 2017
Czech RepublicPresentIntroducedPysek et al., 2002
Czechoslovakia (former)PresentNativeUSDA-ARS, 2017
DenmarkPresentIntroduced Invasive DAISIE, 2017
EstoniaPresentNativeUSDA-ARS, 2017
FinlandPresentIntroduced Invasive DAISIE, 2017
FrancePresentNativeUSDA-ARS, 2017
-CorsicaPresentIntroducedDAISIE, 2017Naturalized
GermanyPresentDAISIE, 2017; USDA-ARS, 2017
GreecePresentNativeUSDA-ARS, 2017
HungaryPresentNativeUSDA-ARS, 2017
IrelandPresentIntroducedUSDA-ARS, 2017Naturalized
ItalyPresentNativeUSDA-ARS, 2017
LatviaPresentNativeUSDA-ARS, 2017
LithuaniaPresentNativeUSDA-ARS, 2017
LuxembourgPresentIntroducedDAISIE, 2017Naturalized
MoldovaPresentNativeUSDA-ARS, 2017
NetherlandsPresentNativeUSDA-ARS, 2017
NorwayPresentIntroduced Invasive DAISIE, 2017
PolandPresentNativeUSDA-ARS, 2017
RomaniaPresentNativeUSDA-ARS, 2017
Russian FederationPresentNativeUSDA-ARS, 2017
-Central RussiaPresentNativeUSDA-ARS, 2017
-Eastern SiberiaPresentNativeUSDA-ARS, 2017
-Northern RussiaPresentNativeUSDA-ARS, 2017
-Russian Far EastPresentNativeUSDA-ARS, 2017
-Southern RussiaPresentNativeUSDA-ARS, 2017
-Western SiberiaPresentNativeUSDA-ARS, 2017
SpainPresentNativeUSDA-ARS, 2017
SwedenPresentIntroduced Invasive DAISIE, 2017
SwitzerlandPresentNativeUSDA-ARS, 2017
UKPresentIntroducedUSDA-ARS, 2017Naturalized
-Channel IslandsPresentIntroducedDAISIE, 2017Naturalized
Yugoslavia (former)PresentNativeUSDA-ARS, 2017
Yugoslavia (Serbia and Montenegro)PresentNativeUSDA-ARS, 2017

Oceania

AustraliaPresentIntroducedUSDA-ARS, 2017
New ZealandPresentIntroducedUSDA-ARS, 2017

History of Introduction and Spread

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Melilotus officinalis has been intentionally introduced into tropical, subtropical and temperate regions of the world as a forage and nitrogen-fixing crop (FAO, 2017; USDA-ARS, 2017), and has often escaped from cultivation.

In North America, the earliest report of Melilotus was made in 1664, although the species was not identified (Turkington et al., 1978). The species M. officinalis was cultivated as a fodder crop in Prince Edward Island before 1850 (Turkington et al., 1978). In the United States, it has been cultivated as a forage crop and soil builder since the early 20th century (Turkington et al., 1978).  To date, it is present in all 50 states of the USA and is spreading in western Greenland, and the Yukon and the Northwest Territories in Canada. It has become invasive and is spreading across floodplains in northern Montana, the Yukon region, southern Ontario, the prairies of the Midwestern USA and the Rocky Mountains (Turkington et al., 1978; Wolf et al. 2004; Conn and Seefeldt, 2009; USDA-NRCS, 2017). In Alaska, M. officinalis was introduced in 1913 as a forage and nitrogen-fixing crop. It has since escaped cultivation, invading roadsides, disturbed areas, and the glacial river floodplains of the Stikine, Matanuska, and Nenana rivers (Conn and Seefeldt, 2009).

In China, this species is reported as both native (USDA-ARS, 2017) and introduced. Chen et al. (2013) indicate that it was introduced in the 1980s to improve the production of forage grasses.  Currently it is reported as a weed spreading into different ecosystems in at least 22 provinces or municipalities (Chen et al., 2013).

Risk of Introduction

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The risk of introduction of Melilotus officinalis is very high.  As a plant often considered useful, it has been intentionally introduced to many temperate and tropical regions and has recurrently escaped from cultivation.  It is also a prolific seeder, with seeds that remain viable for many years, and well adapted to a wide range of habitats. Therefore, even when its use in agriculture has declined in recent years, the likelihood of it colonizing new areas still remains high.

Habitat

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Melilotus officinalis can be found growing as a weed in grasslands, disturbed sites, prairies, savannas, dunes, hillsides, ravine shores, roadsides and forest edges (Turkington et al., 1978; Klein, 2011; Flora of China, 2017; Hilty, 2016; USDA-NRCS, 2017). It grows well in direct sunlight and in partially shaded sites (USDA-NRCS, 2017). Although disturbed areas are preferred, it is sufficiently aggressive to invade natural prairie remnants, where it often becomes the dominant species (Riper and Larsob, 2009; Hilty, 2016). It can also be found growing as a weed in pastures, farms and agricultural lands (Chen et al., 2009).

Hosts/Species Affected

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Melilotus officinalis is listed as a weed in farmlands and grasslands in China (Chen et al., 2009). More specifically, in North America it is listed as a problematic weed in canola (oilseed rape) and wheat fields (Turkington et al., 1978; Conn and Seefeldt, 2009).

Host Plants and Other Plants Affected

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Plant nameFamilyContext
Medicago sativa (lucerne)FabaceaeMain
Triticum (wheat)PoaceaeMain

Growth Stages

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

List of Symptoms/Signs

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SignLife StagesType
Cardiovascular Signs / Tachycardia, rapid pulse, high heart rate Sign
Cardiovascular Signs / Weak pulse, small pulse Sign
Digestive Signs / Anorexia, loss or decreased appetite, not nursing, off feed Sign
Digestive Signs / Bloody stools, faeces, haematochezia Sign
Digestive Signs / Decreased amount of stools, absent faeces, constipation Sign
Digestive Signs / Melena or occult blood in faeces, stools Sign
General Signs / Abnormal proprioceptive positioning, knuckling Sign
General Signs / Back swelling, mass back region Sign
General Signs / Forefoot swelling, mass front foot, feet Sign
General Signs / Forelimb lameness, stiffness, limping fore leg Sign
General Signs / Forelimb swelling, mass in fore leg joint and / or non-joint area Sign
General Signs / Generalized lameness or stiffness, limping Sign
General Signs / Generalized weakness, paresis, paralysis Sign
General Signs / Haemorrhage of any body part or clotting failure, bleeding Sign
General Signs / Head, face, ears, jaw, nose, nasal, swelling, mass Sign
General Signs / Hindfoot swelling, mass rear foot, feet Sign
General Signs / Hindlimb lameness, stiffness, limping hind leg Sign
General Signs / Hindlimb swelling, mass in hind leg joint and / or non-joint area Sign
General Signs / Inability to stand, downer, prostration Sign
General Signs / Neck swelling, mass cervical region Sign
General Signs / Pale mucous membranes or skin, anemia Sign
General Signs / Paraparesis, weakness, paralysis both hind limbs Sign
General Signs / Petechiae or ecchymoses, bruises, ecchymosis Sign
General Signs / Reluctant to move, refusal to move Sign
General Signs / Sudden death, found dead Sign
General Signs / Swelling skin or subcutaneous, mass, lump, nodule Sign
General Signs / Swelling, mass external abdomen Sign
General Signs / Thoracic swelling, mass, thorax, chest, ribs, sternum Sign
General Signs / Trembling, shivering, fasciculations, chilling Sign
Nervous Signs / Dullness, depression, lethargy, depressed, lethargic, listless Sign
Reproductive Signs / Abortion or weak newborns, stillbirth Sign
Reproductive Signs / Bloody milk, red, pink, brown milk Sign
Respiratory Signs / Dyspnea, difficult, open mouth breathing, grunt, gasping Sign
Respiratory Signs / Epistaxis, nosebleed, nasal haemorrhage, bleeding Sign
Respiratory Signs / Increased respiratory rate, polypnea, tachypnea, hyperpnea Sign
Skin / Integumentary Signs / Skin edema Sign

Biology and Ecology

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Genetics

The chromosome number reported for the genus Melilotus is n = 8, and a chromosome count of 2n = 16 is reported for M. officinalis (Turkington et al., 1978).

Reproductive Biology

Melilotus officinalis produces numerous hermaphroditic flowers that grow in long slender spike-like clusters.  Anthesis is diurnal and the nectar attracts many kinds of insects, including bees, wasps, flies, butterflies and beetles (Hilty, 2016). In North America, this species shows high out-crossing rates and a very low incidence of self-pollination (Klein, 2011). It is a prolific seeder with the potential to produce between 35,000 and 100,000 seeds/plant. Seeds can remain viable in the soil for up to 30 years (Klein, 2011; USDA-NRCS, 2017).

Physiology and Phenology

In China, M. officinalis has been recorded flowering from May to September and fruiting from June to October (Flora of China, 2017). In North America it has been recorded flowering from April to September (USDA-NRCS, 2017); in Alaska flowers are produced from June to September (Klein, 2011).

Longevity

M. officinalis is an annual or biennial herb, but under suitable conditions it can also grow as a short-lived perennial (Ogle et al., 2008; USDA-NRCS, 2017).

Associations

M. officinalis forms a symbiotic association with Rhizobium bacteria (Hilty, 2016; USDA-NRCS, 2017). The caterpillars of various Phoebis butterflies and Hemiargus isola [Echinargus isola] eat the foliage, flowers, or buds. The caterpillars of the moth Walshia miscecolorella [Mompha amorphella] bore into the stems and roots (Hilty, 2016). A variety of insects are attracted to the flowers – see above under Reproductive Biology.

Environmental Requirements

M. officinalis is well adapted to a wide range of climatic conditions, but prefers full or partial sun and moist to slightly dry conditions (Hilty, 2016).  It is commonly found on calcareous soils and grow best on rich loams and clay loams with pH levels of 5 or higher. It is tolerant of fire and high alkaline and saline soils (Ghaderi-Far et al., 2010; Klein, 2011; USDA-NRCS, 2017).  It is drought-tolerant once established, only requiring enough moisture for establishment (see next paragraph), after which plants are able to survive under extremely dry conditions (Turkington et al., 1978; Ghaderi-Far et al., 2010). In Alaska, it occurs in sites with less than 170 mm annual precipitation and wintertime temperatures as low as -50°C (Conn and Seefeldt, 2009).

Ghaderi-Far et al. (2010) studied seed germination in particular. Laboratory and greenhouse germination experiments showed that germination is sensitive to drought stress and completely inhibited at a potential of -1 MPa.  However, it is tolerant to salinity -- salinity stress up to 90 mM has no effect on seed germination. Percentages of seed germination >92% have been observed at pH = 5-6, declining to 80% at pH 4 and to 42% at pH 9.  The base, optimum and ceiling germination temperatures reported are 0ºC, 18ºC and 34ºC, respectively.

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])
BS - Steppe climate Tolerated > 430mm and < 860mm annual precipitation
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)
Cf - Warm temperate climate, wet all year Preferred Warm average temp. > 10°C, Cold average temp. > 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 Tolerated 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)
67 45

Air Temperature

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Parameter Lower limit Upper limit
Absolute minimum temperature (ºC) -50
Mean annual temperature (ºC) 10 25

Rainfall

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ParameterLower limitUpper limitDescription
Mean annual rainfall<170>1000mm; lower/upper limits

Rainfall Regime

Top of page Bimodal
Uniform

Soil Tolerances

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Soil drainage

  • free

Soil reaction

  • acid
  • alkaline
  • neutral
  • very alkaline

Soil texture

  • light
  • medium

Special soil tolerances

  • saline

Natural enemies

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Natural enemyTypeLife stagesSpecificityReferencesBiological control inBiological control on
Ascochyta caulicola Pathogen not specific
Ascochyta meliloti Pathogen not specific
Cercospora davisii Pathogen not specific
Echinargus isola Herbivore not specific
Mompha amorphella Herbivore not specific
Phytophthora cactorum Pathogen not specific
Sclerotinia trifoliorum Pathogen not specific

Notes on Natural Enemies

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The main diseases and herbivores affecting Melilotus officinalis, according to FAO (2017), are:

  • rot (Sclerotinia trifoliorum)
  • spring black stem (Ascochyta meliloti)
  • summer black stem (Cercospora davisii)
  • stem canker (Ascochyta caulicola)
  • root rot (Phytophthora cactorum)
  • caterpillars of Hemiargus isola [Echinargus isola]
  • caterpillars Walshia miscecolorella [Mompha amorphella]

Means of Movement and Dispersal

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Melilotus officinalis spreads by seeds.  It is a prolific seeder with the potential to produce between 35,000 and 100,000 seeds/plant. Seeds can remain viable in the soil for up to 30 years (Klein, 2011; USDA-NRCS, 2017).

Natural Dispersal (Non-Biotic)

Rainwater runoff and stream flow are the most important means of seed dispersal (Klein, 2011; USDA-NRCS, 2017).

Accidental Introduction

Seeds of M. officinalis can be dispersed on vehicle tyres and agricultural machinery and as a contaminant in cereal grains and soil (Klein, 2011; USDA-NRCS, 2017).

Intentional Introduction

M. officinalis has been intentionally introduced as a forage crop, a soil builder, and a nectar source for honeybees (Klein, 2011; USDA-ARS, 2017).

Pathway Causes

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CauseNotesLong DistanceLocalReferences
Crop production Yes Yes
Escape from confinement or garden escapeEscaped from cultivation Yes Yes USDA-NRCS, 2017
ForageOften planted as forage crop Yes Yes USDA-NRCS, 2017
Habitat restoration and improvementPlanted as soil improver – nitrogen-fixing species Yes Yes USDA-ARS, 2017
Hitchhikere.g. vehicles, machinery, grain, soil Yes Yes Klein, 2011
Medicinal useUsed as medicinal herb Yes Yes USDA-ARS, 2017

Pathway Vectors

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VectorNotesLong DistanceLocalReferences
Debris and waste associated with human activitiesseeds Yes Yes USDA-NRCS, 2017
Machinery and equipmentSeeds as a contaminant Yes Yes Klein, 2011
Soil, sand and gravel Yes Yes
Land vehiclesSeeds as a contaminant Yes Klein, 2011
WaterMost important means of seed dispersal Yes Klein, 2011

Impact Summary

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CategoryImpact
Positive and negative
Positive and negative
Positive

Economic Impact

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Improperly cured forage from Melilotus officinalis can be toxic to livestock (USDA-ARS, 2017). The species is also a problematic weed in canola and wheat fields (Turkington et al., 1978; Ghaderi-Far et al., 2010; USDA-NRCS, 2017), and is listed as a noxious weed in Canada and the USA.

Environmental Impact

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Impact on Habitats

Melilotus officinalis is an aggressive allelopathic weed that forms dense monospecific stands that displace and inhibit the establishment of native vegetation (Klein, 2011; USDA-NRCS, 2017).

As a nitrogen-fixing legume with large taproots, it has the potential to alter soil conditions and nutrient cycling. In invaded ecosystems, changes in the nitrogen distribution may ultimately shift the composition and structure of native plant communities (Wolf et al., 2004).

It can also reduce light and soil moisture levels in highly invaded areas (YISC, undated; USDA-NRCS, 2017).

It also alters the frequency of natural fires in invaded ecosystems. In North America, it is reduces the occurrence of natural fires and consequently degrades native grassland communities that depend on recurrent fires (USDA-NRCS, 2017).

Ecosystems invaded by M. officinalis include Alaska glacial river floodplains and roadsides adjacent to natural areas (Conn and Seefeldt, 2009; USDA-NRCS, 2017), prairies across Canada, and national parks and protected areas in the United States such as the Rocky Mountain National Park in Colorado, the Badlands National Park and the North American Great Plains (Wolf and Rohrs, 2001; Wolf et al., 2004; Riper and Larsob, 2009; YISC, undated).

Impact on Biodiversity

Melilotus officinalis is an aggressive weed with the potential to strongly decrease the diversity and abundance of all other native and alien plant species (Conn and Seefeldt, 2009; Wolf and Rohrs, 2001; Wolf et al., 2004; Riper and Larsob, 2009; YISC, undated; USDA-NRCS, 2017). For more information on its effects on their habitats, see above under 'Impact on Habitats'.

Social Impact

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Melilotus officinalis can form dense and tall thickets that often cover guide rails and sign posts, creating a hazard for motorists (Turkington et al., 1978).

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
  • 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
  • Modification of nutrient regime
  • Modification of successional patterns
  • Monoculture formation
  • Negatively impacts agriculture
  • Negatively impacts animal health
  • Reduced amenity values
  • Reduced native biodiversity
  • Threat to/ loss of native species
Impact mechanisms
  • Allelopathic
  • Competition - monopolizing resources
  • Competition - shading
  • Competition - smothering
  • Poisoning
  • Rapid growth
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
  • Difficult to identify/detect in the field
  • Difficult/costly to control

Uses

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Melilotus officinalis has been planted as a forage and nitrogen-fixing crop, as a green manure for soil improvement and as a valuable plant for honey production (Turkington et al., 1978; USDA-ARS, 2017). In North America it has been extensively used for soil stabilization and reclamation projects (Ogle et al., 2008). It is also used for hay, silage or pasture. It is, however, less palatable than many other legumes because of its bitter taste caused by the chemical coumarin in the tissues.

In the chemical industry, dicoumarol is extracted from this species, for use as a blood thinner and anticoagulant in rat and mouse poisons and also for treating human ailments (Ogle et al., 2008; USDA-NRCS, 2017).

The flowers and seeds of M. officinalis are sometimes used as a food flavouring (Xi'an Pincredit, 2018).

Uses List

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Animal feed, fodder, forage

  • Fodder/animal feed
  • Forage

Environmental

  • Erosion control or dune stabilization
  • Land reclamation
  • Soil improvement

Human food and beverage

  • Food additive
  • Honey/honey flora

Materials

  • Chemicals
  • Green manure

Medicinal, pharmaceutical

  • Source of medicine/pharmaceutical

Similarities to Other Species/Conditions

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Melilotus officinalis can be easily confused with Astragalus spp., Medicago spp., and Trifolium spp. These can be recognized by the following traits:

  • Astragalus spp. have compound leaves with 8-11 pairs of leaflets.
  • Medicago and Trifolium species have three leaflets but the flowers are in round heads.

Melilotus is a small genus comprising only 22 species of herbs; M. officinalis and M. alba are the weedy species with the most extensive distributions. M. alba can be easily distinguished from M. officinalis by its white flowers.

Prevention and Control

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Physical/mechanical control

Small infestations of Melilotus officinalis may be controlled by hand pulling before seeds are set, and mowing close to the ground. The stands should be cut just before flowering, and checked a week later for missed or partly cut plants (USDA-NRCS, 2017). Pulling or cutting will have to be repeated over a number of years to deplete the seed bank (YISC, undated).

Chemical control

Herbicides such as chlorsulfuron, 2,4-DB, clopyralid, triclopyr, and 2,4-D have been recommended for the control of M. officinalis (Conn and Seefeldt, 2009).

IPM

Several studies have shown that an integrated approach using herbicides together with non-chemical means might be the most effective for control in the long term (Conn and Seefeldt, 2009; YISC, undated; USDA-NRCS, 2017). Because seeds remain viable for a long time, treated sites should be monitored for several years following control actions.

Bibliography

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Draft datasheet under review

References

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Acevedo-Rodríguez P, Strong MT, 2012. Catalogue of the Seed Plants of the West Indies. Washington DC, USA: Smithsonian Institution, 1192 pp. [Smithsonian Contributions to Botany, 98] http://botany.si.edu/Antilles/WestIndies/catalog.htm

Chen C, Huang D, Zhang Y, Zheng H, Wang K, 2013. Invasion of farmland-grassland ecosystems by the exotic sweet clovers, Melilotus officinalis and M. albus. Journal of Food, Agriculture & Environment, 11:1012-1016

Chen H, Zhao Y, Hu L, 2009. Eco-productive Paradigm for Farming-pastoral Zone in North China. Beijing, China: China Agriculture Press.

Conn, J. S., Seefeldt, S. S., 2009. Invasive white sweetclover (Melilotus officinalis) control with herbicides, cutting, and flaming. Invasive Plant Science and Management, 2(3), 270-277. http://www.wssa.net doi: 10.1614/IPSM-08-118.1

DAISIE, 2017. DAISIE: Delivering Alien Invasive Species Inventories for Europe. European Invasive Alien Species Gateway. www.europe-aliens.org/default.do

Dickson, T. L., Wilsey, B. J., Busby, R. R., Gebhart, D. L., 2010. Melilotus officinalis (yellow sweetclover) causes large changes in community and ecosystem processes in both the presence and absence of a cover crop. Biological Invasions, 12(1), 65-76. http://www.springerlink.com/content/a60364j3106663x5/?p=643d6f2bcf2443108a7dd1a7e75ce0ac&pi=5 doi: 10.1007/s10530-009-9430-7

FAO, 2017. FAOSTAT: Food and Agricultural Organization Statistical database, Crop production. Rome, Italy: Food and Agriculture Organization of the United Nations. http://faostat3.fao.org/

Flora of China Editorial Committee, 2017. Flora of China. St. Louis, Missouri and Cambridge, Massachusetts, USA: Missouri Botanical Garden and Harvard University Herbaria. http://www.efloras.org/flora_page.aspx?flora_id=2

Ghaderi-Far, F., Gherekhloo, J., Alimagham, M., 2010. Influence of environmental factors on seed germination and seedling emergence of yellow sweet clover (Melilotus officinalis). Planta Daninha, 28(3), 463-469. http://www.scielo.br/pdf/pd/v28n3/02.pdf doi: 10.1590/S0100-83582010000300002

Hilty J, 2017. Weedy Wildflowers of Illinois. http://www.illinoiswildflowers.info

IABIN, 2017. Red de informacion sobre especies invasoras (Information network on invasive species). Inter-American Biodiversity Information Network (IABIN). http://www.oas.org/en/sedi/dsd/iabin/

ILDIS, 2017. International Legume Database and Information Service: World Database of Legumes (version 10). Reading, UK: School of Plant Sciences, University of Reading. http://www.ildis.org/

Klein H, 2011. Yellow sweetclover Melilotus officinalis (L.) Lam. Anchorage, Alaska, USA: Alaska Natural Heritage Program, University of Alaska, 2 pp. http://accs.uaa.alaska.edu/files/invasive-species/Melilotus_officinalis_BIO_MEOF.pdf

Mir C, 2012. Estrategia Nacional de Especies Exóticas Invasoras Realizado en el marco del Proyecto “Mitigando las amenazas de las especies exóticas invasoras en el Caribe Insular”. Santo Domingo, Dominican Republic: Ministerio de Medio Ambiente y Recursos Naturales

Missouri Botanical Garden, 2017. Tropicos database. St. Louis, Missouri, USA: Missouri Botanical Garden. http://www.tropicos.org/

Ogle D, John L, Tilley D, 2008. Plant Guide for yellow sweetclover (Melilotus officinalis (L.) Lam. and white sweetclover (M. alba Medik). Aberdeen, Idaho, USA: USDA-Natural Resources Conservation Service, Idaho Plant Materials Center

Pyšek, P., Sádlo, J., Mandák, B., 2002. Catalogue of alien plants of the Czech Republic. Preslia, 74(2), 97-186.

Riper, L. C. van, Larson, D. L., 2009. Role of invasive Melilotus officinalis in two native plant communities. Plant Ecology, 200(1), 129-139. http://springerlink.metapress.com/link.asp?id=100328 doi: 10.1007/s11258-008-9438-6

Stevens PF, 2012. Angiosperm Phylogeny Website. http://www.mobot.org/MOBOT/research/APweb/

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

Turkington, R. A., Cavers, P. B., Rempel, E., 1978. The biology of Canadian weeds. 29. Melilotus alba Desr. and M. officinalis (L.) Lam. Canadian Journal of Plant Science, 58(2), 523-527.

USDA-ARS, 2017. Germplasm Resources Information Network (GRIN). Online Database. National Germplasm Resources Laboratory, Beltsville, USA. http://www.ars-grin.gov/cgi-bin/npgs/html/tax_search.pl

USDA-NRCS, 2017. The PLANTS Database. Baton Rouge, USA: National Plant Data Center. http://plants.usda.gov/

Wolf, J. J., Beatty, S. W., Seastedt, T. R., 2004. Soil characteristics of Rocky Mountain National Park grasslands invaded by Melilotus officinalis and M. alba. Journal of Biogeography, 31(3), 415-424. http://www.blackwellpublishing.com/jbi doi: 10.1046/j.0305-0270.2003.00983.x

Wolf, J. J., Rohrs, J., 2001. The influence of physical soil conditions on the formation of root nodules of Melilotus officinalis in the montane zone of Rocky Mountain National Park. European Journal of Soil Biology, 37(1), 51-57. doi: 10.1016/S1164-5563(01)01068-8

Xi'an Pincredit, 2018. Melilotus officinalis extract. Xi'an, Shaanxi, China. http://5eqoer.pinherbs.com/

YISC, undated. White Sweetclover, Yellow Sweetclover -- Melilotus albus, Melilotus officinalis. Yukon. Canada: Yukon Invasive Species Council. https://www.yukoninvasives.com/pdf_docs/Factsheet%20Sweetclover2f.pdf

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.

Principal Source

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Draft datasheet under review

Contributors

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08/05/17: Original text by:

Julissa Rojas-Sandoval, Department of Botany, Smithsonian National Museum of Natural History, Washington DC, USA

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