Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Datasheet

Juncus effusus
(common rush)

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Datasheet

Juncus effusus (common rush)

Summary

  • Last modified
  • 27 September 2018
  • Datasheet Type(s)
  • Invasive Species
  • Host Plant
  • Preferred Scientific Name
  • Juncus effusus
  • Preferred Common Name
  • common rush
  • Taxonomic Tree
  • Domain: Eukaryota
  •   Kingdom: Plantae
  •     Phylum: Spermatophyta
  •       Subphylum: Angiospermae
  •         Class: Monocotyledonae
  • Summary of Invasiveness
  • J. effusus is a perennial in the rush family (Juncaceae). It is a wetland species with a broad, nearly global distribution. Across its broad range numerous morphological entities have been described at the subs...

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Pictures

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PictureTitleCaptionCopyright
Juncus effusus (Soft rush, goza plant, Japanese mat rush, bog rush); Juncus Bog, invasive habit, surrounding a boardwalk. Puu Kukui, Maui, Hawaii, USA. February, 2009.
TitleInvasive habit
CaptionJuncus effusus (Soft rush, goza plant, Japanese mat rush, bog rush); Juncus Bog, invasive habit, surrounding a boardwalk. Puu Kukui, Maui, Hawaii, USA. February, 2009.
Copyright©Forest Starr & Kim Starr - CC BY 4.0
Juncus effusus (Soft rush, goza plant, Japanese mat rush, bog rush); Juncus Bog, invasive habit, surrounding a boardwalk. Puu Kukui, Maui, Hawaii, USA. February, 2009.
Invasive habitJuncus effusus (Soft rush, goza plant, Japanese mat rush, bog rush); Juncus Bog, invasive habit, surrounding a boardwalk. Puu Kukui, Maui, Hawaii, USA. February, 2009.©Forest Starr & Kim Starr - CC BY 4.0
Juncus effusus (soft rush, goza plant, Japanese mat rush, bog rush); habit. Puu Kukui, Maui, Hawaii, USA. February, 2009.
TitleHabit
CaptionJuncus effusus (soft rush, goza plant, Japanese mat rush, bog rush); habit. Puu Kukui, Maui, Hawaii, USA. February, 2009.
Copyright©Forest Starr & Kim Starr - CC BY 4.0
Juncus effusus (soft rush, goza plant, Japanese mat rush, bog rush); habit. Puu Kukui, Maui, Hawaii, USA. February, 2009.
HabitJuncus effusus (soft rush, goza plant, Japanese mat rush, bog rush); habit. Puu Kukui, Maui, Hawaii, USA. February, 2009.©Forest Starr & Kim Starr - CC BY 4.0
Juncus effusus (Soft rush, goza plant, Japanese mat rush, bog rush); plant base. Kipahulu Valley Haleakala National Park, Maui, Hawaii, USA. February, 2009.
TitlePlant base
CaptionJuncus effusus (Soft rush, goza plant, Japanese mat rush, bog rush); plant base. Kipahulu Valley Haleakala National Park, Maui, Hawaii, USA. February, 2009.
Copyright©Forest Starr & Kim Starr - CC BY 4.0
Juncus effusus (Soft rush, goza plant, Japanese mat rush, bog rush); plant base. Kipahulu Valley Haleakala National Park, Maui, Hawaii, USA. February, 2009.
Plant baseJuncus effusus (Soft rush, goza plant, Japanese mat rush, bog rush); plant base. Kipahulu Valley Haleakala National Park, Maui, Hawaii, USA. February, 2009.©Forest Starr & Kim Starr - CC BY 4.0
Juncus effusus (Soft rush, goza plant, Japanese mat rush, bog rush); seedhead. Kipahulu Valley, Haleakala National Park, Maui, Hawaii, USA. February, 2009.
TitleSeedhead
CaptionJuncus effusus (Soft rush, goza plant, Japanese mat rush, bog rush); seedhead. Kipahulu Valley, Haleakala National Park, Maui, Hawaii, USA. February, 2009.
Copyright©Forest Starr & Kim Starr - CC BY 4.0
Juncus effusus (Soft rush, goza plant, Japanese mat rush, bog rush); seedhead. Kipahulu Valley, Haleakala National Park, Maui, Hawaii, USA. February, 2009.
SeedheadJuncus effusus (Soft rush, goza plant, Japanese mat rush, bog rush); seedhead. Kipahulu Valley, Haleakala National Park, Maui, Hawaii, USA. February, 2009.©Forest Starr & Kim Starr - CC BY 4.0

Identity

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Preferred Scientific Name

  • Juncus effusus

Preferred Common Name

  • common rush

Other Scientific Names

  • Juncus bogotensis Kunth
  • Juncus communis E. Mey
  • Juncus griscomii Fernald
  • Juncus laevis Wallr.
  • Juncus polyanthemus BUCHEN.

International Common Names

  • English: bog rush; Japanese mat rush; soft rush
  • Spanish: junco de esteras; junquera
  • French: jonc à lier; jonc diffus; jonc épars
  • Chinese: deng xin cao

Local Common Names

  • Colombia: junco; junco chiquito; totora; totorilla
  • Japan: igusa

EPPO code

  • IUNEF (Juncus effusus)

Summary of Invasiveness

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J. effusus is a perennial in the rush family (Juncaceae). It is a wetland species with a broad, nearly global distribution. Across its broad range numerous morphological entities have been described at the subspecific or varietal level. The species has been introduced to Hawaii, Australia and New Zealand. In addition, several subspecies have been introduced outside of their native ranges and often occur sympatrically with J. effusus subspecies in their native ranges.

Where J. effusus is native it is a desirable species in natural wetland habitats, but can become weedy in wet agricultural areas. Where introduced it can displace native plants, alter habitat structure and outcompete rare plant species. In Hawaii, it competes with rare species, including three species listed as Endangered by the US Fish and Wildlife Service. It can often be a weed of agriculture, particularly displacing desirable forage species in livestock pastures. Introduced subspecies could hybridize with native subspecies where they occur together. 

Taxonomic Tree

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  • Domain: Eukaryota
  •     Kingdom: Plantae
  •         Phylum: Spermatophyta
  •             Subphylum: Angiospermae
  •                 Class: Monocotyledonae
  •                     Order: Cyperales
  •                         Family: Juncaceae
  •                             Genus: Juncus
  •                                 Species: Juncus effusus

Notes on Taxonomy and Nomenclature

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Juncus is a genus with a worldwide distribution, consisting of about 300 species (Brooks and Clemants, 2000). J. effusus was described by Linnaeus in 1753. The species has a wide global distribution and exhibits morphological variation across its range. Because of this variation the delineation of species limits and infraspecific taxa has been problematic and controversial. According to Zika (2003), “The Juncus effusus L. complex vexes systematists”.

The Juncus effusus complex consists of J. effusus and close relatives, particularly J. conglomeratus and J. pylaei, although many other species with narrow distributions have been described. Some authors break this complex up into more than one species, e.g. (Hämet-Ahti, 1980; Balslev, 1996; Kirschner, 2002; Weakley, 2016), or treat these taxa at the level of variety (Fernald and Wiegand, 1910). Many subspecies or varieties have also been described including subsp. solutus and others (Hämet-Ahti, 1980; Kirschner, 2002; Zika, 2003). In contrast, some treat it as a highly variable species, lumping all of the above taxa into the single variable species, J. effusus, such as Engelmann (1868), and recently Brooks and Clemants (2000).

Authors who treat the J. effusus complex as a group of 3 species, and with J. effusus consisting of several subspecies, e.g. Hämet-Ahti (1980) and Kirschner (2002), note that some of these taxa have become naturalized outside of their natural ranges. J. conglomeratus, native of the Old World, is naturalized in North America, New Zealand, and Venezuela. J. pylaei, native of northeastern North America, is naturalized in the northwestern USA. J. effusus subsp. effusus, native of the Old World, is naturalized in the Americas, eastern Asia, and Australia. J. effusus subsp. solutus, native to eastern North America, is naturalized in western North America. Complicating matters further, J. effusus forms hybrids with other species, including J. conglomeratus, J. inflexus and J. pallidus (Wilcox, 2010).

Some localized have been described as new species that were later considered introductions of J. effusus. For example, J. luxurians was described from New Zealand, but was later considered to be conspecific with J. effusus which is probably introduced (Edgar, 1964).

Description

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The following description has been adapted from Kirschner (2002).

J. effusus is a perennial plant, with culms to 1.5 m tall, densely caespitose with short rhizomes. Stem terete, without leaf blades, green, smooth to inconspicuously ridged; ridges 40-70, pith continuous, cataphylls 3(-4). Inflorescence pseudolateral (appearing lateral), diffuse or rarely dense, of 50-120 separate flowers. Lower bract usually several times longer than inflorescence, appearing as extension of culm. Tepals 1.5-3 mm long, outer ones longest, lanceolate, apiculate, green to light brown with scarious margin. Stamens 3 (-6); anthers 0.4-0.7 mm long, slightly shorter than filaments. Style very short; stigmas 0.6-1 mm long. Capsule (1.61) 2-2.5 mm long, subequal to or slightly exceeding perianth, subspheroid to ovoid, broadly ellipsoid or obovate, obtuse or slightly retuse, not or shortly mucronate, unilocular, triseptate, light brown. Seeds 0.5 × 0.2-0.3 mm, obliquely ovoid, reticulate, without appendages. 

Distribution

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J. effusus has a broad native range, occurring in Europe, western and central Asia, North America to South America, and the Caribbean (Brooks and Clemants, 2000; Kirschner, 2002; Missouri Botanical Garden, 2016; USDA-NRCS, 2016). Delineation of the native and introduced range of J. effusus is complicated by taxonomic problems in the J. effusus complex. For the purposes of this datasheet, the range is for J. effusus as delineated by Kirschner (2002), excluding segregate taxa such as J. conglomeratus and J. pylaei. Further complicating discussions of native and introduced ranges is the infraspecific taxonomy of the species. Different subspecies have been introduced within the ranges of other subspecies. Overall Kirschner (2002) stated that “it is almost impossible to distinguish primary and secondary occurrences”. Most floras treating J. effusus and allies do not present good data on ranges of native verses introduced subspecies.           

At the species level, J. effusus has been introduced to Hawaii, Australia, and New Zealand. Various subspecies, particularly subsp. effusus and subsp. solutus have been introduced outside of their native ranges. J. effusus subsp. effusus is native to Europe, southwest Asia, and northern Africa. It has been introduced from North America to South America, eastern Asia, Australia, Mauritius, Madagascar, Argentina, and Chile. J. effusus subsp. solutus is native to eastern North America, with populations in the western USA probably representing introductions.

J. effusus subsp. laxus is native to Atlantic islands, sub-Saharan Africa, Madagascar and nearby islands, and possibly Spain and Portugal. It has been introduced to the Cape Province of South Africa. J. effusus subsp. pacificus is native to western North America from Baha California to Alaska. J. effusus subsp. austrocalifornicus is native to southern California to northern Mexico. No introduced populations of these latter two subspecies have been reported (Kirschner, 2002). 

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

AfghanistanPresentNativeKirschner, 2002subsp. effusus
ArmeniaPresentNativeKirschner, 2002subsp. effusus
AzerbaijanPresentNativeKirschner, 2002subsp. effusus
BhutanPresentNativeWu et al., 2000; Missouri Botanical Garden, 2016
ChinaPresentNativeKirschner, 2002; Missouri Botanical Garden, 2016
-AnhuiPresentNativeWu et al., 2000
-FujianPresentNativeWu et al., 2000
-GansuPresentNativeWu et al., 2000
-GuangdongPresentNativeWu et al., 2000
-GuangxiPresentNativeWu et al., 2000
-GuizhouPresentNativeWu et al., 2000
-HebeiPresentNativeWu et al., 2000
-HeilongjiangPresentNativeWu et al., 2000
-HenanPresentNativeWu et al., 2000
-Hong KongAbsent, unreliable recordPIER, 2016Not listed by Bentham (1861), Corlett (1992) or others
-HubeiPresentNativeWu et al., 2000
-HunanPresentNativeWu et al., 2000
-JiangsuPresentNativeWu et al., 2000
-JiangxiPresentNativeWu et al., 2000
-JilinPresentNativeWu et al., 2000
-LiaoningPresentNativeWu et al., 2000
-ShandongPresentNativeWu et al., 2000
-SichuanPresentNativeWu et al., 2000
-TibetPresentNativeWu et al., 2000
-YunnanPresentNativeWu et al., 2000
-ZhejiangPresentNativeWu et al., 2000
Georgia (Republic of)PresentNativeKirschner, 2002; Missouri Botanical Garden, 2016
IndiaPresentNativeWu et al., 2000; Kirschner, 2002
-SikkimPresentNativeWu et al., 2000
IndonesiaPresentNativeWu et al., 2000; PIER, 2016
IranPresentNativeKirschner, 2002subsp. effusus
IraqPresentNativeKirschner, 2002subsp. effusus
JapanPresentNativeWu et al., 2000; Missouri Botanical Garden, 2016
Korea, Republic ofPresentNativeWu et al., 2000; Missouri Botanical Garden, 2016
LaosPresentNativeWu et al., 2000; Missouri Botanical Garden, 2016
MalaysiaPresentWu et al., 2000
NepalPresentNativeWu et al., 2000; Missouri Botanical Garden, 2016
PhilippinesAbsent, unreliable recordEdgar, 1964; PIER, 2016Probably refers to J. decipiens subsp. medianus
Sri LankaPresentNativeWu et al., 2000; Missouri Botanical Garden, 2016
TaiwanPresentNativeWu et al., 2000; Kirschner, 2002
ThailandPresentNativeWu et al., 2000; Missouri Botanical Garden, 2016
TurkeyPresentNativeKirschner, 2002subsp. effusus
VietnamPresentNativeWu et al., 2000; Missouri Botanical Garden, 2016

Africa

AlgeriaPresentNativeKirschner, 2002subsp. effusus
BurundiPresentNativeKirschner, 2002subsp. laxus
Congo Democratic RepublicPresentNativeKirschner, 2002subsp. laxus
EthiopiaPresentNativeWeimarck, 1946; Kirschner, 2002subsp. effusus
GabonPresentNativeMissouri Botanical Garden, 2016
KenyaPresentNativeKirschner, 2002subsp. laxus
MadagascarPresentNativeHumbert and Leroy, 1946; Kirschner, 2002; Kirschner, 2002; Missouri Botanical Garden, 2016
MauritiusPresentIntroducedKirschner, 2002; Kirschner, 2002subsp. effusus
MoroccoPresentNativeKirschner, 2002subsp. effusus
RéunionPresentNativeKirschner, 2002subsp. laxus
RwandaPresentNativeKirschner, 2002subsp. laxus
Saint HelenaPresentIntroducedWeimarck, 1946Tristan de Cunha, St. Helena
South AfricaPresentNativeWeimarck, 1946; Kirschner, 2002; Kirschner, 2002; Missouri Botanical Garden, 2016
Spain
-Canary IslandsPresentNativeKirschner, 2002subsp. effusus
TanzaniaPresentNativeKirschner, 2002subsp. laxus
UgandaPresentNativeKirschner, 2002subsp. laxus
ZimbabwePresentNativeKirschner, 2002subsp. laxus

North America

CanadaPresentPresent based on regional distribution.
-British ColumbiaPresentNativeKirschner, 2002; Kirschner, 2002; Missouri Botanical Garden, 2016; USDA-NRCS, 2016
-ManitobaPresentNativeKirschner, 2002; USDA-NRCS, 2016
-New BrunswickPresentNativeKirschner, 2002; USDA-NRCS, 2016
-Newfoundland and LabradorPresentNativeKirschner, 2002subsp. effusus, subsp. solutus
-Nova ScotiaPresentNativeKirschner, 2002; USDA-NRCS, 2016
-OntarioPresentNativeKirschner, 2002; USDA-NRCS, 2016
-Prince Edward IslandPresentNativeKirschner, 2002subsp. effusus
-QuebecPresentNativeKirschner, 2002; USDA-NRCS, 2016
MexicoPresentNativeBalslev, 1996; Kirschner, 2002; Missouri Botanical Garden, 2016
USAPresentIntroducedKirschner, 2002subsp. effusus
-AlabamaPresentNativeUSDA-NRCS, 2016
-AlaskaPresentNativeUSDA-NRCS, 2016
-ArizonaPresentNativeUSDA-NRCS, 2016
-ArkansasPresentNativeUSDA-NRCS, 2016
-CaliforniaPresentNativeUSDA-NRCS, 2016
-ColoradoPresentNativeUSDA-NRCS, 2016
-ConnecticutPresentNativeUSDA-NRCS, 2016
-DelawarePresentNativeUSDA-NRCS, 2016
-District of ColumbiaPresentNativeUSDA-NRCS, 2016
-FloridaPresentNativeUSDA-NRCS, 2016
-GeorgiaPresentNativeUSDA-NRCS, 2016
-HawaiiPresentIntroduced1900 Invasive Wester, 1992; Wysong et al., 2007; Lau and Frohlich, 2012; PIER, 2016; USDA-NRCS, 2016
-IdahoPresentNativeUSDA-NRCS, 2016
-IllinoisPresentNativeUSDA-NRCS, 2016
-IndianaPresentNativeUSDA-NRCS, 2016
-IowaPresentNativeUSDA-NRCS, 2016
-KansasPresentNativeUSDA-NRCS, 2016
-KentuckyPresentNativeUSDA-NRCS, 2016
-LouisianaPresentNativeUSDA-NRCS, 2016
-MainePresentNativeUSDA-NRCS, 2016
-MarylandPresentNativeUSDA-NRCS, 2016
-MassachusettsPresentNativeUSDA-NRCS, 2016
-MichiganPresentNativeUSDA-NRCS, 2016
-MinnesotaPresentNativeUSDA-NRCS, 2016
-MississippiPresentNativeUSDA-NRCS, 2016
-MissouriPresentNativeUSDA-NRCS, 2016
-MontanaPresentNativeUSDA-NRCS, 2016
-NebraskaPresentNativeUSDA-NRCS, 2016
-NevadaPresentNativeUSDA-NRCS, 2016
-New HampshirePresentNativeUSDA-NRCS, 2016
-New JerseyPresentNativeUSDA-NRCS, 2016
-New MexicoPresentNativeUSDA-NRCS, 2016
-New YorkPresentNativeUSDA-NRCS, 2016
-North CarolinaPresentNativeUSDA-NRCS, 2016
-North DakotaPresentNativeUSDA-NRCS, 2016
-OhioPresentNativeUSDA-NRCS, 2016
-OklahomaPresentNativeUSDA-NRCS, 2016
-OregonPresentNativeUSDA-NRCS, 2016
-PennsylvaniaPresentNativeUSDA-NRCS, 2016
-Rhode IslandPresentNativeUSDA-NRCS, 2016
-South CarolinaPresentNativeUSDA-NRCS, 2016
-TennesseePresentNativeUSDA-NRCS, 2016
-TexasPresentNativeUSDA-NRCS, 2016
-VermontPresentNativeUSDA-NRCS, 2016
-VirginiaPresentNativeUSDA-NRCS, 2016
-WashingtonPresentNativeUSDA-NRCS, 2016
-West VirginiaPresentNativeUSDA-NRCS, 2016; USDA-NRCS, 2016
-WisconsinPresentNativeUSDA-NRCS, 2016

Central America and Caribbean

Costa RicaPresentNativeBalslev, 1996; Kirschner, 2002; Missouri Botanical Garden, 2016
El SalvadorPresentNativeBalslev, 1996; Kirschner, 2002; Missouri Botanical Garden, 2016
GuadeloupePresentNativeBalslev, 1996; Missouri Botanical Garden, 2016
GuatemalaPresentNativeBalslev, 1996; Kirschner, 2002; Missouri Botanical Garden, 2016
HaitiPresentNativeBalslev, 1996; Kirschner, 2002; Acevedo-Rodriguez et al., 2015
HondurasPresentNativeBalslev, 1996; Kirschner, 2002; Missouri Botanical Garden, 2016

South America

ArgentinaPresentNativeKirschner, 2002; FOA, 2016; Missouri Botanical Garden, 2016
BoliviaPresentNativeBalslev, 1996; Kirschner, 2002; Missouri Botanical Garden, 2016
BrazilPresentNativeBalslev, 1996; Kirschner, 2002; Missouri Botanical Garden, 2016
-Minas GeraisPresentNativeMissouri Botanical Garden, 2016
-ParanaPresentNativeMissouri Botanical Garden, 2016
-Rio Grande do SulPresentNativeMissouri Botanical Garden, 2016
-Santa CatarinaPresentNativeMissouri Botanical Garden, 2016
-Sao PauloPresentNativeMissouri Botanical Garden, 2016
ChilePresentNativeKirschner, 2002; Missouri Botanical Garden, 2016
ColombiaPresentNativeBalslev, 1996; Kirschner, 2002; Missouri Botanical Garden, 2016
EcuadorPresentNativeBalslev, 1996; Kirschner, 2002; Missouri Botanical Garden, 2016
PeruPresentNativeBalslev, 1996; Kirschner, 2002; Missouri Botanical Garden, 2016
VenezuelaPresentNativeBalslev, 1996; Kirschner, 2002; Missouri Botanical Garden, 2016

Europe

AlbaniaPresentNativeKirschner, 2002subsp. effusus
AustriaPresentNativeKirschner, 2002subsp. effusus
BelarusPresentNativeKirschner, 2002subsp. effusus
BelgiumPresentNativeKirschner, 2002; Missouri Botanical Garden, 2016
BulgariaPresentNativeKirschner, 2002subsp. effusus
CyprusPresentNativeKirschner, 2002subsp. effusus
Czechoslovakia (former)PresentNativeKirschner, 2002subsp. effusus
DenmarkPresentNativeKirschner, 2002subsp. effusus
EstoniaPresentNativeKirschner, 2002subsp. effusus
Faroe IslandsPresentNativeKirschner, 2002subsp. effusus
FinlandPresentNativeKirschner, 2002subsp. effusus
FrancePresentNativeKirschner, 2002subsp. effusus
-CorsicaPresentNativeKirschner, 2002subsp. effusus
GermanyPresentNativeKirschner, 2002subsp. effusus
GreecePresentNativeKirschner, 2002subsp. effusus
HungaryPresentNativeKirschner, 2002subsp. effusus
IcelandPresentNativeKirschner, 2002subsp. effusus
IrelandPresentNativeKirschner, 2002subsp. effusus
ItalyPresentNativeKirschner, 2002subsp. effusus
LatviaPresentNativeKirschner, 2002subsp. effusus
LithuaniaPresentNativeKirschner, 2002subsp. effusus
MacedoniaPresentNativeKirschner, 2002subsp. effusus
NetherlandsPresentNativeKirschner, 2002subsp. effusus
NorwayPresentNativeKirschner, 2002subsp. effusus
PolandPresentNativeKirschner, 2002subsp. effusus
PortugalPresentNativeÂlvarez, 1981; Kirschner, 2002; Missouri Botanical Garden, 2016
-AzoresPresentNativeKirschner, 2002subsp. effusus
-MadeiraPresentNativeKirschner, 2002subsp. effusus
RomaniaPresentNative Invasive Kirschner, 2002; Pele et al., 2008
Russian FederationPresentNativeKirschner, 2002subsp. effusus
-Central RussiaPresentNativeKirschner, 2002subsp. effusus
-Eastern SiberiaPresentNativeKirschner, 2002
-Northern RussiaPresentNativeKirschner, 2002subsp. effusus
-Russian Far EastPresentNativeKirschner, 2002subsp. effusus
-Southern RussiaPresentNativeKirschner, 2002subsp. effusus
-Western SiberiaPresentNativeKirschner, 2002subsp. effusus
SpainPresentNativeÂlvarez, 1981; Kirschner, 2002subsp. effusus, subsp. laxus
-Balearic IslandsPresentNativeKirschner, 2002
Svalbard and Jan MayenPresentNativeKirschner, 2002subsp. effusus
SwitzerlandPresentNativeKirschner, 2002subsp. effusus
UKPresentNativeKirschner, 2002subsp. effusus
UkrainePresentNativeOlshansky and Fedoronchuk, 2011subsp. effusus
Yugoslavia (Serbia and Montenegro)PresentNativeKirschner, 2002subsp. effusus

Oceania

AustraliaPresentIntroduced Invasive Edgar, 1964; PIER, 2016
-New South WalesPresentIntroduced Invasive Kirschner, 2002; Downey et al., 2010
-QueenslandPresentIntroduced Invasive AVH, 2016
-South AustraliaPresentIntroduced Invasive Jessop, 1989; AVH, 2016
-TasmaniaPresentIntroduced Invasive Rozefelds et al., 1999; AVH, 2016
-VictoriaPresentIntroduced Invasive Kirschner, 2002; AVH, 2016subsp. effusus
New ZealandWidespreadIntroduced Invasive Edgar, 1964; Esler and Astridge, 1987; Kirschner, 2002; Heiss-Dunlop and Fillery, 2006; Howell, 2008; PIER, 2016
Papua New GuineaAbsent, unreliable recordAVH, 2016; Missouri Botanical Garden, 2016Specimens are of J. decipiens var. meadianus (Wilson, and Johnson, 2001)

History of Introduction and Spread

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J. effusus was introduced to Australia by 1840 (AVH, 2016), New Zealand by 1871 (Esler and Astridge, 1987) and to Hawaii by 1900 (Wester, 1992). Wagner et al. (1999) states that the species has spread from cultivation in Hawaii.

Introductions

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Introduced toIntroduced fromYearReasonIntroduced byEstablished in wild throughReferencesNotes
Natural reproductionContinuous restocking
Australia by 1840 Yes No Kirschner (2002)
Hawaii by 1900 Yes No Wester (1992)
New Zealand by 1871 Yes No Esler and Astridge (1987)

Habitat

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J. effusus is an obligate wetland species. The species grows in a wide range of freshwater wetland habitats including marshes, swamps, wet pastures, and ditches, primarily where water stands for only part of the year (Adamson, 1935; Hämet-Ahti, 1980; Balslev, 1996; Weakley, 2016), and in treeless vegetation in the Australian alps (McDougall et al., 2005). It can grow to elevations of up to 2500 m (Brooks and Clemants, 2000).

Habitat List

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CategorySub-CategoryHabitatPresenceStatus
Terrestrial
Terrestrial – ManagedCultivated / agricultural land Present, no further details
Managed grasslands (grazing systems) Present, no further details
Disturbed areas Present, no further details
Terrestrial ‑ Natural / Semi-naturalRiverbanks Present, no further details
Wetlands Present, no further details
Freshwater
Irrigation channels Present, no further details
Lakes Present, no further details
Reservoirs Present, no further details
Rivers / streams Present, no further details
Ponds Present, no further details

Hosts/Species Affected

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In Europe J. effusus has been recorded as a weed of fodder plantings, pastures, cereals, and root crops (Weber and Gut, 2005). It is a weed of cranberry (Vaccinium macrocarpon) production, invading fields and obstructing irrigation ditches (Ghantous and Sandler, 2015). It can colonize rice fields as soon as they are taken out of production (Elliott, 1821).

Biology and Ecology

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Genetics

J. effusus has a chromosome number of n=40, 42 (Balslev, 1996; Brooks and Clemants, 2000). No genetic analysis of J. effusus has been done on a regional or global basis.

Reproductive Biology

The species is self-compatible (Michalski and Durka, 2012).

Physiology and Phenology

It flowers from early summer through autumn (Álvarez, 1981; Brooks and Clemants, 2000; Weakley, 2016).

Longevity

J. effusus is a long-lived perennial (Brooks and Clemants, 2000).

Climate

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ClimateStatusDescriptionRemark
Af - Tropical rainforest climate Preferred > 60mm precipitation per month
Am - Tropical monsoon climate Preferred Tropical monsoon climate ( < 60mm precipitation driest month but > (100 - [total annual precipitation(mm}/25]))
Aw - Tropical wet and dry savanna climate Preferred < 60mm precipitation driest month (in winter) and < (100 - [total annual precipitation{mm}/25])
BS - Steppe climate Preferred > 430mm and < 860mm annual precipitation
BW - Desert climate Preferred < 430mm annual precipitation
Cf - Warm temperate climate, wet all year Preferred Warm average temp. > 10°C, Cold average temp. > 0°C, wet all year
Cs - Warm temperate climate with dry summer Preferred Warm average temp. > 10°C, Cold average temp. > 0°C, dry summers
Df - Continental climate, wet all year Preferred Continental climate, wet all year (Warm average temp. > 10°C, coldest month < 0°C, wet all year)

Means of Movement and Dispersal

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Natural Dispersal

According to Balslev (1996) swelling of the seed coat when wet causes the inflorescence to turn into heavy, slimy mass, causing the culms to bend to the ground, depositing seeds. The very small seeds have high potential for long-distance dispersal (Michalski and Durka, 2012).

Accidental Introduction

Despite the introduction of J. effusus to new geographic regions, there is little data on causes of introduction. Introductions were probably accidental. Wagner et al. (1999) states that the species has spread from cultivation in Hawaii.

Impact Summary

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

Economic Impact

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In its native range and introduced range J. effusus is a weed of a variety of wet agricultural habitats, including wet pastures and wet agricultural habitats. In the USA it can invade cranberry production areas and impede drainage in adjacent ditches (Ghantous and Sandler, 2015). It can limit grazing for cattle in poorly drained pastures, which do not graze the species (Bakker et al., 1984; Rana and Sellers, 2009). In Europe it is a weed of fodder plantings, pastures, cereals, and root crops (Weber and Gut, 2005). 

Environmental Impact

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Impact on Habitats

Because of its large stature J. effusus can displace other native species (Ervin and Wetzel, 2002), reducing species diversity. It is a troublesome weed in cutaway peatlands in Europe, outcompeting young conifers that have been planted in restoration programs (McCorry and Renou, 2003).  

Impact on Biodiversity

J. effusus competes with rare species in Hawaii, including three species listed as Endangered by the US Fish and Wildlife Service. These include Phyllostegia hispida in Molokai, Phyllostegia mannii in Molokai and Maui, and Sanicula purpurea in Maui (US Fish and Wildlife Service 2011a,b,c).

Threatened Species

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Threatened SpeciesConservation StatusWhere ThreatenedMechanismReferencesNotes
Phyllostegia hispida (hispid phyllostegia)USA ESA listing as endangered species USA ESA listing as endangered speciesHawaiiCompetition - shading; Competition (unspecified)US Fish and Wildlife Service, 2011a
Phyllostegia mannii (Mann's phyllostegia)NatureServe NatureServe; USA ESA listing as endangered species USA ESA listing as endangered speciesHawaiiAllelopathic; Competition - shadingUS Fish and Wildlife Service, 2011b
Sanicula purpurea (purpleflower blacksnakeroot)CR (IUCN red list: Critically endangered) CR (IUCN red list: Critically endangered); USA ESA listing as endangered species USA ESA listing as endangered speciesHawaiiCompetition - shading; Competition (unspecified)US Fish and Wildlife Service, 2011c

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
  • Tolerant of shade
  • Long lived
  • Has high reproductive potential
  • Gregarious
  • Has propagules that can remain viable for more than one year
  • Reproduces asexually
Impact outcomes
  • Altered trophic level
  • Changed gene pool/ selective loss of genotypes
  • Ecosystem change/ habitat alteration
  • Modification of successional patterns
  • Monoculture formation
  • Negatively impacts agriculture
  • Reduced native biodiversity
  • Threat to/ loss of endangered species
  • Threat to/ loss of native species
Impact mechanisms
  • Allelopathic
  • Competition - monopolizing resources
  • Competition - shading
  • Competition
Likelihood of entry/control
  • Highly likely to be transported internationally accidentally
  • Difficult to identify/detect as a commodity contaminant
  • Difficult/costly to control

Uses

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Economic Value

Human uses of J. effusus are currently limited. It has been used traditionally for weaving, including material for sleeping mats, chair seats, and baskets, and the pith serves as a wick for candles and lamps (Porcher, 1869; Balslev, 1996). In China the pith is used for drawing hot Camellia oleifera tea seed oil.

Social Benefit

In China, the outer epidermis is used as a wick for applying the oil to the body for relieving pain. The pith is also used as a tranquilizer and diuretic (Eisenberg et al., 2009).  

Similarities to Other Species/Conditions

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If segregated as distinct species J. effusus can be difficult to distinguish from J. conglomeratus and J. pylaei. Both of these latter species have coarsely grooved, firm culms below the inflorescence with 10-20 ridges, perianth 2.7-3.6 mm long, and sepals that are longer than the capsule and petals. In contrast J. effusus has a soft, finely grooved culm with 25-30 striations, perianth 1.9-2.8 mm long, and sepals equalling the petals (Kirschner, 2002; Weakley, 2016). J. effusus is also similar to the closely related J. decipiens of eastern Asia. It is more slender than J. effusus, and culms have more densely packed pith (Wilson and Johnson, 2001).      

Prevention and Control

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

Containment/Zoning

Downey et al. (2010) assessed J. effusus as a low threat to New South Wales, Australia. 

Control

Physical/Mechanical Control

Physical control of J. effusus is difficult. Repeated mowing has been used effectively in the UK. If mowing is conducted twice/year then biomass can be reduced by 98% (Rana and Sellers, 2009). DiTomaso and Kyser (2013) noted that while repeated mowing may be helpful, mowing more than once/year can often be difficult because of wet conditions. They also found that burning or grazing are not effective, and that hand pulling is not practical. Cultivation followed by reseeding may be effective (DiTomaso and Kyser, 2013). On former agricultural lands with high nutrient levels restoration probably requires topsoil removal, and liming may be of use (Smolders et al., 2008). Ghantous and Sandler (2015) has experimented with burning clumps of the species in cranberry production areas with some success, but on a small scale.

Biological Control

There is no biocontrol for J. effusus, and development of one is unlikely due to the threat to other Juncus species (Froude, 2002; DiTomaso and Kyser, 2013).

Chemical Control

DiTomaso and Kyser (2013) recommend that control of J. effusus can be achieved with herbicides. Formulations of 2,4-D applied in late spring, followed by elimination of grazing to allow reestablishment of native graminoids is recommended. Imazapic is also discussed as a control option with mixed success, although this herbicide is non selective and soil active. The use of 2,4-D is also recommended by Rana and Sellers (2009) for control in Florida pastures. Glyphosate gives good control and can be used with a weed wiper since the rush stands up well above the pasture.

Gaps in Knowledge/Research Needs

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The taxonomy of the J. effusus complex is in serious need of revision (Brooks and Clemants, 2000). Additionally, the threat of hybridization of J. effusus and its subspecies with native taxa needs additional assessment.

References

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Acevedo-Rodriguez, P, Strong, MT, 2015. Flora of the West Indies. Washington DC, USA: Department of Botany, National Museum of Natural History, Smithsonian Institution. http://botany.si.edu/antilles/WestIndies/index.htm

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Ghantous KM, Sandler HA, 2015. Hand-held flame cultivators for spot treatment control of soft rush (Juncus effusus). Weed Technology, 29(1):121-127. http://www.wssajournals.org/doi/abs/10.1614/WT-D-14-00048.1

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Contributors

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12/05/16 Original text by: 

Keith Bradley, Consultant, South Carolina, USA

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