Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Datasheet

Juncus tenuis
(slender rush)

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Datasheet

Juncus tenuis (slender rush)

Summary

  • Last modified
  • 06 November 2018
  • Datasheet Type(s)
  • Invasive Species
  • Preferred Scientific Name
  • Juncus tenuis
  • Preferred Common Name
  • slender rush
  • Taxonomic Tree
  • Domain: Eukaryota
  •   Kingdom: Plantae
  •     Phylum: Spermatophyta
  •       Subphylum: Angiospermae
  •         Class: Monocotyledonae
  • Summary of Invasiveness
  • Juncus tenuis, commonly known as slender rush, is a clump-forming, tufted perennial herb. In its native environment in the Americas, J. tenuis is not usually considered ‘weedy’ since it is relatively s...

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Pictures

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PictureTitleCaptionCopyright
Juncus tenuis (slender rush); habit, in a grassy field.
TitleHabit
CaptionJuncus tenuis (slender rush); habit, in a grassy field.
Copyright©Trevor James/Hamilton, New Zealand
Juncus tenuis (slender rush); habit, in a grassy field.
HabitJuncus tenuis (slender rush); habit, in a grassy field.©Trevor James/Hamilton, New Zealand
Juncus tenuis (slender rush); habit. Native bunched, perennial, common in disturbed settings (e.g. trailsides and roadsides). Possibly the most common of the colonizing (weedy) rushes in southwestern Montana. Bozeman, Montana, USA. September 2009.
TitleHabit
CaptionJuncus tenuis (slender rush); habit. Native bunched, perennial, common in disturbed settings (e.g. trailsides and roadsides). Possibly the most common of the colonizing (weedy) rushes in southwestern Montana. Bozeman, Montana, USA. September 2009.
Copyright©Prof Matt Lavin-2009/Bozeman, Montana, USA - CC BY-SA 2.0
Juncus tenuis (slender rush); habit. Native bunched, perennial, common in disturbed settings (e.g. trailsides and roadsides). Possibly the most common of the colonizing (weedy) rushes in southwestern Montana. Bozeman, Montana, USA. September 2009.
HabitJuncus tenuis (slender rush); habit. Native bunched, perennial, common in disturbed settings (e.g. trailsides and roadsides). Possibly the most common of the colonizing (weedy) rushes in southwestern Montana. Bozeman, Montana, USA. September 2009.©Prof Matt Lavin-2009/Bozeman, Montana, USA - CC BY-SA 2.0
Juncus tenuis (slender rush); habit, of an isolated flowering plant.
TitleHabit
CaptionJuncus tenuis (slender rush); habit, of an isolated flowering plant.
Copyright©Trevor James/Hamilton, New Zealand
Juncus tenuis (slender rush); habit, of an isolated flowering plant.
HabitJuncus tenuis (slender rush); habit, of an isolated flowering plant.©Trevor James/Hamilton, New Zealand
Juncus tenuis (slender rush); habit of young plant.
TitleHabit
CaptionJuncus tenuis (slender rush); habit of young plant.
Copyright©Trevor James/Hamilton, New Zealand
Juncus tenuis (slender rush); habit of young plant.
HabitJuncus tenuis (slender rush); habit of young plant.©Trevor James/Hamilton, New Zealand
Juncus tenuis (slender rush); one of a pair of large membranous auricles at the leaf  base.
TitleAuricle
CaptionJuncus tenuis (slender rush); one of a pair of large membranous auricles at the leaf base.
Copyright©Trevor James/Hamilton, New Zealand
Juncus tenuis (slender rush); one of a pair of large membranous auricles at the leaf  base.
AuricleJuncus tenuis (slender rush); one of a pair of large membranous auricles at the leaf base.©Trevor James/Hamilton, New Zealand
Juncus tenuis (slender rush); flower head.
TitleInflorescence
CaptionJuncus tenuis (slender rush); flower head.
Copyright©Trevor James/Hamilton, New Zealand
Juncus tenuis (slender rush); flower head.
InflorescenceJuncus tenuis (slender rush); flower head.©Trevor James/Hamilton, New Zealand
Juncus tenuis (slender rush); inflorescence, with seed capsules.
TitleInflorescence
CaptionJuncus tenuis (slender rush); inflorescence, with seed capsules.
Copyright©Trevor James/Hamilton, New Zealand
Juncus tenuis (slender rush); inflorescence, with seed capsules.
InflorescenceJuncus tenuis (slender rush); inflorescence, with seed capsules.©Trevor James/Hamilton, New Zealand
Juncus tenuis (slender rush); habit, flowering heads.
TitleFlowering heads
CaptionJuncus tenuis (slender rush); habit, flowering heads.
Copyright©Trevor James/Hamilton, New Zealand
Juncus tenuis (slender rush); habit, flowering heads.
Flowering headsJuncus tenuis (slender rush); habit, flowering heads.©Trevor James/Hamilton, New Zealand
Juncus tenuis (slender rush); close view of flowering heads.
TitleFlowering heads
CaptionJuncus tenuis (slender rush); close view of flowering heads.
Copyright©Trevor James/Hamilton, New Zealand
Juncus tenuis (slender rush); close view of flowering heads.
Flowering headsJuncus tenuis (slender rush); close view of flowering heads.©Trevor James/Hamilton, New Zealand
Juncus tenuis (slender rush); habit, with fruits. Possibly the most common of the colonizing (weedy) rushes in southwestern Montana. Bozeman, Montana, USA. September 2009.
TitleHabit
CaptionJuncus tenuis (slender rush); habit, with fruits. Possibly the most common of the colonizing (weedy) rushes in southwestern Montana. Bozeman, Montana, USA. September 2009.
Copyright©Prof Matt Lavin-2009/Bozeman, Montana, USA - CC BY-SA 2.0
Juncus tenuis (slender rush); habit, with fruits. Possibly the most common of the colonizing (weedy) rushes in southwestern Montana. Bozeman, Montana, USA. September 2009.
HabitJuncus tenuis (slender rush); habit, with fruits. Possibly the most common of the colonizing (weedy) rushes in southwestern Montana. Bozeman, Montana, USA. September 2009.©Prof Matt Lavin-2009/Bozeman, Montana, USA - CC BY-SA 2.0
Juncus tenuis (slender rush); fruits. Possibly the most common of the colonizing (weedy) rushes in southwestern Montana. Bozeman, Montana, USA. September 2009.
TitleFruits
CaptionJuncus tenuis (slender rush); fruits. Possibly the most common of the colonizing (weedy) rushes in southwestern Montana. Bozeman, Montana, USA. September 2009.
Copyright©Prof Matt Lavin-2009/Bozeman, Montana, USA - CC BY-SA 2.0
Juncus tenuis (slender rush); fruits. Possibly the most common of the colonizing (weedy) rushes in southwestern Montana. Bozeman, Montana, USA. September 2009.
FruitsJuncus tenuis (slender rush); fruits. Possibly the most common of the colonizing (weedy) rushes in southwestern Montana. Bozeman, Montana, USA. September 2009.©Prof Matt Lavin-2009/Bozeman, Montana, USA - CC BY-SA 2.0
TitleJuncus tenuis (slender rush); habit, with dry flower heads.
Caption
Copyright©Trevor James/Hamilton, New Zealand
Juncus tenuis (slender rush); habit, with dry flower heads.©Trevor James/Hamilton, New Zealand
Juncus tenuis (slender rush); seed capsules, one opened, to show the many small seeds within.
TitleSeed capsules
CaptionJuncus tenuis (slender rush); seed capsules, one opened, to show the many small seeds within.
Copyright©Trevor James/Hamilton, New Zealand
Juncus tenuis (slender rush); seed capsules, one opened, to show the many small seeds within.
Seed capsulesJuncus tenuis (slender rush); seed capsules, one opened, to show the many small seeds within.©Trevor James/Hamilton, New Zealand

Identity

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Preferred Scientific Name

  • Juncus tenuis Willd.

Preferred Common Name

  • slender rush

Other Scientific Names

  • Juncus bicornis Michx.
  • Juncus chloroticus Schult. & Schult.f.
  • Juncus germanorum Steud.
  • Juncus lucidus Hochst.

International Common Names

  • English: path rush; poverty rush; soft rush

Local Common Names

  • : sharp rush; slender yard rush; wiregrass
  • Austria: Zart-Simse
  • China: jian bei deng xin cao
  • Czech Republic: s¡tina tenk 
  • Denmark: tue-siv
  • Estonia: sale luga
  • France: jone grèle
  • Germany: zarte binse; zarte binse
  • Latvia: laibasis viksris
  • Lithuania: maigais donis
  • Norway: ballastsiv
  • Poland: sit chudy
  • Sweden: syltág

Summary of Invasiveness

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Juncus tenuis, commonly known as slender rush, is a clump-forming, tufted perennial herb. In its native environment in the Americas, J. tenuis is not usually considered ‘weedy’ since it is relatively small and commonly grows as a plant of pathways and road verges. It is named as a minor weed of alfalfa in Oklahoma, USA. It has also been reported to sometimes invade urban lawns and to cause problems on golf courses in North America. It has been introduced to parts of Asia, Africa, Europe and Oceania, most probably unintentionally since seeds are sticky and readily attach to animals, clothes and car tyres. It is regarded as invasive in Hawaii (PIER, 2016). It has also been recently reported among invasive species in Croatian forestry (Horvat & Franjic, 2016).

Taxonomic Tree

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

Notes on Taxonomy and Nomenclature

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ITIS (2016) quotes synonyms of this species as Juncus macer Gray, J. tenuis var. tenuis Willd., J. tenuis var. multicornis E. Mey., and J. tenuis var. williamsii Fernald, none of which are accepted. Others are indicated by the The Plant List (2013) and by Stace (2010) but are not now in common use.

Description

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The following is modified from PIER, 2016, after Wagner et al., 1999:

Perennial herb, stems 10-60 cm tall, 1-2 mm in diameter, growing in clumps from short, densely branching rhizomes (Flora of North America Editorial Committee, 2016). Leaves numerous, basal, crowded, blades variable in length, 7-30 cm long, 1-1.3 mm wide, sheaths loose with wide transparent margins, prolonged into white membranous auricles up to 5 mm long. Flowers 3 to many borne singly on one side of the rachis, in relatively compact dichasial cymes (all branches below the terminal flower are in regular opposite pairs) 1-7 cm long, forming less than 1/3 of the plant height, bracts 2-3, leaf-like, usually much longer than the inflorescence. Each flower subtended by 2 hyaline, triangular-ovate membranous bracteoles. Perianth parts greenish, lanceolate, 3-4.5 mm long, apex tapering to a point, outer ones slightly reflexed at the tip, inner ones with wide transparent margins towards the base. Stamens 6, half as long as perianth, anthers shorter than filaments. Capsules reddish brown, 1-celled, broadly ovoid, thin-walled, slightly beaked, 2/3 of or hardly shorter than the perianth. Seeds pale brown, oblong, 0.3-0.4 mm long, slightly pointed at both ends. The seeds become sticky when wet.

Distribution

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J. tenuis is often said to be native to North America (Healy and Edgar, 1980; Stace, 2010; USDA-ARS, 2016), but Wagner et al., 1999 (cited in PIER, 2016) claims a more cosmopolitan native distribution, including Europe, Asia and Australia. However, whatever its origin, it is now widespread in many parts of the world.

Scully (1889) and Preagar (1934), both quoted in Richards (1943) suggested that the species may be native to southwest Ireland because it is found there in very remote, little-visited districts and that it grows in natural habits and not as a roadside weed.

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

ArmeniaPresentIntroducedUSDA-ARS, 2016
AzerbaijanPresentIntroducedUSDA-ARS, 2016
ChinaPresentIntroducedUSDA-ARS, 2016
-HeilongjiangPresentIntroducedFlora of China Editorial Committee, 2016
-HenanPresentIntroducedFlora of China Editorial Committee, 2016
-JiangxiPresentIntroducedFlora of China Editorial Committee, 2016
-ShandongPresentIntroducedFlora of China Editorial Committee, 2016
-ZhejiangPresentIntroducedFlora of China Editorial Committee, 2016
IndiaPresentIntroducedFlora of China Editorial Committee, 2016
-MeghalayaPresentIntroducedBhaumik, 2010
JapanPresentIntroducedUSDA-ARS, 2016
Korea, Republic ofPresentIntroducedFlora of China Editorial Committee, 2016
TaiwanPresentIntroducedUSDA-ARS, 2016
TurkeyPresentIntroducedUSDA-ARS, 2016

Africa

MadagascarPresentIntroducedUSDA-ARS, 2016
MauritiusPresentIntroducedUSDA-ARS, 2016
South AfricaPresentIntroducedUSDA-ARS, 2016

North America

CanadaPresentPresent based on regional distribution.
-AlbertaPresentNativeUSDA-ARS, 2016
-British ColumbiaPresentNativeUSDA-ARS, 2016
-ManitobaPresentNativeUSDA-ARS, 2016
-New BrunswickPresentNativeUSDA-ARS, 2016
-Newfoundland and LabradorPresentNativeUSDA-ARS, 2016
-Northwest TerritoriesPresentNativeUSDA-ARS, 2016
-OntarioPresentNativeUSDA-ARS, 2016
-Prince Edward IslandPresentNativeUSDA-ARS, 2016
-SaskatchewanPresentNativeUSDA-ARS, 2016
-Yukon TerritoryPresentNativeUSDA-ARS, 2016
MexicoPresentNativeUSDA-ARS, 2016Chiapas, Coahtuila, Guerrero, Hidalgo, Oaxaca, Veracruz
USAPresentPresent based on regional distribution.
-AlabamaPresentNativeUSDA-ARS, 2016
-AlaskaPresentNativeUSDA-ARS, 2016
-ArizonaPresentNativeUSDA-ARS, 2016
-ArkansasPresentNativeUSDA-ARS, 2016
-CaliforniaPresentNativeUSDA-ARS, 2016
-ColoradoPresentNativeUSDA-ARS, 2016
-ConnecticutPresentNativeUSDA-ARS, 2016
-DelawarePresentNativeUSDA-ARS, 2016
-District of ColumbiaPresentNativeFlora of North America Editorial Committee, 2016
-FloridaPresentNativeUSDA-ARS, 2016
-GeorgiaPresentNativeUSDA-ARS, 2016
-HawaiiPresentIntroduced Invasive Wagner et al., 1999; USDA-ARS, 2016Hawaii, Kauai, Maui, Molokai
-IdahoPresentNativeUSDA-ARS, 2016
-IllinoisPresentNativeUSDA-ARS, 2016
-IndianaPresentNativeUSDA-ARS, 2016
-IowaPresentNativeUSDA-ARS, 2016
-KansasPresentNativeUSDA-ARS, 2016
-KentuckyPresentNativeUSDA-ARS, 2016
-LouisianaPresentNativeUSDA-ARS, 2016
-MainePresentNativeUSDA-ARS, 2016
-MarylandPresentNativeUSDA-ARS, 2016
-MassachusettsPresentNativeUSDA-ARS, 2016
-MichiganPresentNativeUSDA-ARS, 2016
-MinnesotaPresentNativeUSDA-ARS, 2016
-MississippiPresentNativeUSDA-ARS, 2016
-MissouriPresentNativeUSDA-ARS, 2016
-MontanaPresentNativeUSDA-ARS, 2016
-NebraskaPresentNativeUSDA-ARS, 2016
-NevadaPresentNativeUSDA-ARS, 2016
-New HampshirePresentNativeUSDA-ARS, 2016
-New JerseyPresentNativeUSDA-ARS, 2016
-New MexicoPresentNativeUSDA-ARS, 2016
-New YorkPresentNativeUSDA-ARS, 2016
-North CarolinaPresentNativeUSDA-ARS, 2016
-North DakotaPresentNativeUSDA-ARS, 2016
-OhioPresentNativeUSDA-ARS, 2016
-OklahomaPresentNativeUSDA-ARS, 2016
-OregonPresentNativeUSDA-ARS, 2016
-PennsylvaniaPresentNativeUSDA-ARS, 2016
-Rhode IslandPresentNativeUSDA-ARS, 2016
-South CarolinaPresentNativeUSDA-ARS, 2016
-South DakotaPresentNativeUSDA-ARS, 2016
-TennesseePresentNativeUSDA-ARS, 2016
-TexasPresentNativeUSDA-ARS, 2016
-UtahPresentNativeUSDA-ARS, 2016
-VermontPresentNativeUSDA-ARS, 2016
-VirginiaPresentNativeUSDA-ARS, 2016
-WashingtonPresentNativeUSDA-ARS, 2016
-West VirginiaPresentNativeUSDA-ARS, 2016
-WisconsinPresentNativeUSDA-ARS, 2016
-WyomingPresentNativeUSDA-ARS, 2016

Central America and Caribbean

Costa RicaPresentNativeUSDA-ARS, 2016
El SalvadorPresentNativeUSDA-ARS, 2016
GuatemalaPresentNativeUSDA-ARS, 2016
HondurasPresentNativeUSDA-ARS, 2016
JamaicaPresentNativeUSDA-ARS, 2016
Puerto RicoPresentNativeUSDA-ARS, 2016

South America

ArgentinaPresentNativeUSDA-ARS, 2016
BoliviaPresentNativeUSDA-ARS, 2016
BrazilPresentNativeUSDA-ARS, 2016
ColombiaPresentNativeUSDA-ARS, 2016
EcuadorPresentNativeUSDA-ARS, 2016
ParaguayPresentNativeUSDA-ARS, 2016
PeruPresentNativeUSDA-ARS, 2016
VenezuelaPresentNativeUSDA-ARS, 2016Menda, Tachera

Europe

AustriaPresentIntroducedUSDA-ARS, 2016
BelarusPresentIntroducedUSDA-ARS, 2016
BelgiumPresentIntroducedUSDA-ARS, 2016
Bosnia-HercegovinaPresentIntroducedUSDA-ARS, 2016
BulgariaPresentIntroducedUSDA-ARS, 2016
CroatiaPresentIntroducedUSDA-ARS, 2016
Czech RepublicPresentIntroducedUSDA-ARS, 2016
DenmarkPresentIntroducedUSDA-ARS, 2016
EstoniaPresentIntroducedUSDA-ARS, 2016
FinlandPresentIntroducedUSDA-ARS, 2016
FrancePresentIntroducedUSDA-ARS, 2016
GermanyPresentIntroducedUSDA-ARS, 2016
GreecePresentIntroducedUSDA-ARS, 2016
IrelandPresentIntroducedUSDA-ARS, 2016
ItalyPresentIntroducedUSDA-ARS, 2016
LatviaPresentIntroducedUSDA-ARS, 2016
LithuaniaPresentIntroducedUSDA-ARS, 2016
MacedoniaPresentIntroducedUSDA-ARS, 2016
MontenegroPresentIntroducedUSDA-ARS, 2016
NetherlandsPresentIntroducedUSDA-ARS, 2016
NorwayPresentIntroducedUSDA-ARS, 2016
PolandPresentIntroducedUSDA-ARS, 2016
PortugalPresentPresent based on regional distribution.
-AzoresPresentIntroducedUSDA-ARS, 2016
-MadeiraPresentIntroducedUSDA-ARS, 2016
RomaniaPresentIntroducedUSDA-ARS, 2016
Russian FederationPresentPresent based on regional distribution.
-Western SiberiaPresentIntroducedUSDA-ARS, 2016
SerbiaPresentIntroducedUSDA-ARS, 2016
SlovakiaPresentIntroducedUSDA-ARS, 2016
SloveniaPresentIntroducedUSDA-ARS, 2016
SpainPresentIntroducedUSDA-ARS, 2016
SwedenPresentIntroducedUSDA-ARS, 2016
SwitzerlandPresentIntroducedUSDA-ARS, 2016
UKPresentIntroducedUSDA-ARS, 2016

Oceania

AustraliaPresentIntroducedUSDA-ARS, 2016
-New South WalesPresentIntroducedCouncil of Heads of Australasian Herbaria, 2016; USDA-ARS, 2016
-TasmaniaPresentIntroducedCouncil of Heads of Australasian Herbaria, 2016
-VictoriaPresentIntroducedCouncil of Heads of Australasian Herbaria, 2016
-Western AustraliaPresentIntroducedCouncil of Heads of Australasian Herbaria, 2016
New ZealandPresentIntroduced Invasive Healy and Edgar, 1980; ISSG, 2016; USDA-ARS, 2016

History of Introduction and Spread

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J. tenuis is possibly native to North America but has been spread from there, presumably accidentally as its small sticky seeds readily adhere to other plant material, animal fur, and packing material. In addition it is often found in close proximity to humans, growing as it does alongside paths. It was first recorded in Britain in 1795 (under the name of Juncus gracilis Sm., and later Juncus mercer (Richards, 1943; Stace, 2010) but was not then recorded again until 1844 and 1863 (Richards, 1943). These scarce early records suggest that this species was indeed introduced to Britain. Since then it has become ‘locally frequent throughout most of the British Isles except the Outer Isles’ (Stace, 2010).

According to Richards (1943) it was first observed in continental Europe in 1824 and there too, by 1943 it was ‘widely distributed from France and Northern Italy to Jutland. Bohus and Smaland in Sweden and eastwards to Bohemia, the middle Dnieper, upper Volga, Volga-Don, Crimea, Caucusus and Transcaucasia in the USSR.’ It now seems to be widespread throughout much of Europe and is still spreading. Seeds were accidentally distributed as far afield as Australia and New Zealand in the late 1800s, and even to remote St Helena in the South Atlantic (ISSG, 2016).

Introductions

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Introduced toIntroduced fromYearReasonIntroduced byEstablished in wild throughReferencesNotes
Natural reproductionContinuous restocking
Australia 1902 Yes Yes Council of Heads of Australasian Herbaria (2016) Sydney, New South Wales
New Zealand 1877 Yes Healy and Edgar (1980) Amuri, Canterbury and Ngaruawahia
UK 1795 Yes Richards (1943) Rare, in marshy ground among mountains, Angusshire

Risk of Introduction

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J. tenuis has small, sticky seeds which are easily overlooked. For this reason there is considerable danger of the species being accidentally introduced into new countries, and of further spread within those countries where it is already present. However, its spread is most likely to be limited to paths, tracks and roadsides.

Habitat

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Both in its native Americas and in Europe and elsewhere this species seems to prefer disturbed habitats where competition from other plants is at a minimum. It is commonly found alongside pathways in a range of places like open woodlands, gravely seeps, pastures, abandoned fields and other waste areas. It is better adapted to surviving on hard-trodden paths and tracks than many other species.

For example Stace (2010) in Britain mentions its habitat as ‘damp, barish ground on roadsides, tracks and paths’. In New Zealand, too, Healy (1982) says of the species ‘tolerant of trampling and mechanical injury and therefore a weed of shingle drives, farm yards, paths, tracks, and roadways: in some localities forms distinct colonies along the shoulders of bitumen roads, and in country districts along shoulders and crowns of shingle roads.’ However, Healy (1982) also points out that this is not the only habitat and that it is ‘a persistent weed of damp pastures, swamp margins, damp waste places, poached (i.e. trampled) gateways: in recent years has become more significant in pastures in some higher rainfall districts.’

In its native environment in North America Hilty (2011) said that the species is very common in Illinois, where its habitats include ‘open woodlands, gravelly seeps, footpaths with compacted soil (where it is especially common), pastures and abandoned fields, gravelly margins of roadways, and barren waste areas.’       

Almost all authors in a wide range of countries stress that the typical habitat of J. tenuis is along footpaths or tracks or roadways, due partly to its method of seed dispersal and partly to an apparent preference for compacted soil. However Richards (1943) also listed a number of mostly British plant communities in which the species can be found, sometimes growing in dense shade where it can flower. He says, for example, that it is found in dense shade ‘in the woods proper on the edges of drains’ in Aldershot Wood, Dorset, Britain.

Habitat List

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CategorySub-CategoryHabitatPresenceStatus
Freshwater
Terrestrial
 
Terrestrial – ManagedCultivated / agricultural land Present, no further details
Disturbed areas Present, no further details
Rail / roadsides Present, no further details
Urban / peri-urban areas Present, no further details

Biology and Ecology

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Genetics

2n= 30, 32, 84 (Encyclopedia of Life, 2016; Flora of China Editorial Committee, 2016), while Flora of North America Editorial Committee (2016) quotes 2n=80 and Stace (2010), in Britain, indicates 2n=32, 40, 80, 84.

Reproductive Biology

In Wales and northern Britain plants flower between late June and August but flowering may continue spasmodically until the first frosts (Richards, 1943). The flowers open between 7 am and 8 am and most close by mid-day but some may stay open until late afternoon. Fruits ripen from July to September and some capsules continue to open until the onset of winter. Some seed may remain in the capsules until the following spring.

In North America, plants flower in spring or early summer (Flora of North America Editorial Committee, 2016).

The flowers are very slightly protogynous and pollination is by wind. Richards (1943) quotes Graebner (1934) in saying that the anthers begin to dehisce about an hour after the flower opens and this is completed between 9 and 10 am. The ripe stigmas are already visible before the flowers opened.

Richards (1943) mentioned that seeds were counted in nine capsules and the average number was 268, ranging from 87 to 348. Salisbury (1974) counted the seeds in 91 capsules, with an average of 175.8 seeds per capsule and a range of 60 to over 450. From these data and a knowledge of capsule number Salisbury suggested an average seed output of about 30,000 seeds per plant. He also said that the number of infructescences (presumably flower heads and therefore capsules) per plant is usually six or seven but that as many as 28 have been observed.

The small, yellow-brown seeds have an average weight of 0.014 to 0.0174 mg and become very mucilaginous and sticky when wet, making them easily transported on footwear, tyres, feathers, fur. This is partly why plants are common along footpaths and animal trails (Salisbury, 1974).

Physiology and Phenology

Salisbury (1974) observed that about 30% of sown seed germinated in some cases in the autumn after their ripening and in other cases in the following spring, presumably depending on climatic conditions. Mayer & Poljakoff-Mayber (1963) record that germination is geater in the light.

Richards (1943) observed that the outer layer of the testa becomes mucilaginous and swells enormously on wetting, the seeds often forcing the capsule open. ‘During rainy weather the large slimy transparent masses of seeds resembling frog’s spawn adhere to the dehisced capsules.’ The seeds are readily spread on the feet of people, mammals and birds, and on the tyres of vehicles.

Richards (1943) says plants are ‘strikingly variable in size and when in flower from 10 to 60 cm high, but usually 15-35 cm: possibly this great variability may be partly due to some plants flowering in their first summer.’ The main flowering season is summer to autumn in Western Europe and North America (Richards, 1943; Pojar and MacKInnon, 1994).

In Britain, Richards (1943) says that fruit ripen from July to September but that some capsules continue to ripen until the onset of winter. In North America, however, Hoffman (2012) says that harvesting seeds (for conservation projects) occurs typically inearly July in the Willamette Valley in Oregon.

Longevity

Plants appear to be long-lived, even on upland sites, and can probably produce seed for over 5 years (Hoffman, 2012). However erect shoots die down in winter, leaving rosettes of green leaves (Richards, 1943). In Britain Richards (1943) suggests that the species is a short-lived perennial but quotes Graebner (1934) as saying that in Europe it tends to die away after a few years but in moderately wet places the tufts reached a much greater diameter and could survive for several years. By contrast in wet or very shady habitats plants almost always died out after their second year.

Seed stored under dry conditions remain viable for at least 2 years (Richards, 1943). Mayer & Poljakoff-Mayber (1963) record that seed can retain viability in the field for at least 4 years even under flooded conditions.

Activity Patterns

Hoffman (2012) says that seeds are not dormant and germinate in the spring as soils warm. By contrast, Salisbury (1974) says that in some years, germination can take place in either the autumn or spring after seed was sown in October, presumably depending on climatic conditions and possible the provenance of the seeds.

Erect shoots die down completely in winter, leaving rosettes of green leaves (Westmorland, 1941-2), mentioned by Richards (1943).

Population Size and Structure

Richards (1943) said that that this species does not form extensive stands like other members of the genus but grows in small, isolated tufts. Sometimes, however, these tufts may be so abundant that they are in lateral contact and form a more or less continuous zone along the roadside.

Environmental Requirements

The species is most commonly found growing in open places with no or little competition from other species. Richards (1943), for example says ‘On paths through grass fields it only occurs where the [foot] traffic is sufficient to wear bare patches in the turf’. However in Europe it is also found along ‘woodland rides’ and sometimes ‘in dense shade’. In North America, too, Hoffman (2012) says that it can grow in ‘wet, compacted clayey soils in highly trafficked and/or rocky areas.’ He also says that it typically prefers full sun to light shade. Hoffman also says that it grows on freshwater sites with saturated soil in winter and dry conditions in summer, and adds that it is common in disturbed areas with seeps and springs such as prairies, meadows, shaded roads and ditches.

According to Richards (1943) the plants generally, if not always, grow on slightly acid, more or less base-deficient soils of clayey, loamy or gritty texture.

Climate

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ClimateStatusDescriptionRemark
Cf - Warm temperate climate, wet all year Preferred Warm average temp. > 10°C, Cold average temp. > 0°C, wet all year
Cs - Warm temperate climate with dry summer Preferred Warm average temp. > 10°C, Cold average temp. > 0°C, dry summers

Latitude/Altitude Ranges

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Latitude North (°N)Latitude South (°S)Altitude Lower (m)Altitude Upper (m)
60 33

Air Temperature

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Parameter Lower limit Upper limit
Mean annual temperature (ºC) 4 21
Mean maximum temperature of hottest month (ºC) 21 32
Mean minimum temperature of coldest month (ºC) -12 6

Rainfall

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ParameterLower limitUpper limitDescription
Mean annual rainfall1200mm; lower/upper limits

Notes on Natural Enemies

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In Britain there seem to be no records of insect visitors to the plant, nor of parasites and diseases (Richards, 1943). Hoffman (2012) also says that in North America no significant pests are associated with this species. Some rust has been observed on plants but this does not seem to affect seed production.

Means of Movement and Dispersal

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Natural Dispersal (non-biotic)

Although the seeds are very small and light they are unlikely to be spread by air currents because the seeds are very mucilaginous and in rainy weather clump together to form large transparent masses of seeds (Richards, 1943).

Vector Transmission (biotic)

The small seeds become very mucilaginous and sticky when wet, making them easily transported on clothing, footwear, tyres, feathers and fur. This is partly why plants are common along footpaths and animal trails (Salisbury, 1974). Richards (1943) suggested that the accelerated spread of the species through Britain in the first half of the 20th century may be due to the increase in vehicular traffic which can carry the seeds attached to the tyres. Seeds of J. tenuis remain viable after ingestion by sika deer, so some dispersal may occur this way (Ishikawa, 2010).

Accidental Introduction

Presumably this is how this mostly useless rush species has been distributed around the world, probably because its tiny, sticky seeds have been spread by attachment to clothing and footwear as well as to vegetable matter used as animal fodder or packing material long before biosecurity was considered important.

Intentional Introduction

J. tenuis appears to be readily available from a number of North American nurseries (California Native Plant Society, 2016), presumably either in plant or seed form and so could easily be spread by post to other countries.

Impact Summary

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CategoryImpact
Environment (generally) Negative

Economic Impact

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Where J. tenuis grows in pastures it presumably reduces the availability of useful palatable pasture species and must therefore reduce pasture productivity to some extent. However, although it does grow in pastures, its most common habitat seems to be at the edges of footpaths and roads where it presumably has very little economic effect.

Hilty (2011) says that it is usually avoided by mammalian herbivores since the foliage becomes stringy and tough when mature.

However on golf courses in the United States it can be a problem in limited areas like fairways, because it can be difficult to mow (Hutto et al., 2007).

J. tenuis is named as a weed of alfalfa in Oklahoma, USA, where the comment is ‘occasionally present, but seldom a problem’ (Weeds of Oklahoma, 2016).

Environmental Impact

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Environmental Impact

There seems to be little mention in published work of any environmental impacts of this small and mostly inconspicuous rush.

Impact on Habitats

The only report of adverse effects on habitats seems to be that on the nesting sites of the St. Helena plover. On the isolated South Atlantic island of St. Helena, J. tenuis is one of the grass-like species considered responsible for the reduction in suitable nesting sites for the critically endangered Saint Helena plover (Charadrius sanctaehelenae) (Varnham, 2006; IUCN, 2016).

Social Impact

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Hutto et al. (2007) say that on golf courses this species can be a problem in high-traffic areas where golf carts or equipment consistently run in rough areas along the fairways: it can then become established in fairways if seed is dispersed there.

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
  • Pioneering in disturbed areas
  • Tolerant of shade
  • Highly mobile locally
  • Fast growing
  • Has high reproductive potential
  • Gregarious
  • Has propagules that can remain viable for more than one year
Likelihood of entry/control
  • Highly likely to be transported internationally accidentally
  • Difficult to identify/detect as a commodity contaminant
  • Difficult to identify/detect in the field

Uses

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Economic Value

In North America, Hoffman (2012) points out that the seeds of this species are actually harvested in Oregon and used for erosion control, for biofilters, and as a groundcover or landscaping plant.

Social Benefit

Poverty rush was used medicinally by the Native American Cherokee in an infusion used as a wash to strengthen babies, and prevent against lameness. Additionally, it was used in a decoction to dislodge spoiled saliva (Hamel and Chiltosky, 1975, cited in Hoffman, 2012).

 Native American Iroquois runners and lacrosse players used poverty rush in a decoction or infusion to induce vomiting, or as a wash (Herrick, 1977, cited in Hoffman, 2012)

Native American Cherokee used poverty rush stems and plant material as cordage to bind dough in oak leaves for baking bread (Hamel and Chiltoskey, 1975, cited in Hoffman, 2012).

Environmental Services

Hoffman (2012) lists a number of environmental uses for J. tenuis in its native North America, where it is used for erosion control along streambanks and in drainage stabilization due to its bunched growth form, and its ability to grow in saturated and compacted soils. Another use is as a biofilter where it can be used in the bottom of constructed bioswales as a groundlayer. It is also used in the scrub shrub layer as a ground cover in constructed wetlands (Jurries, 2003). In landscaping it is also useful as a groundcover, or water plant, in a rain garden due to its ability to grow in compacted and saturated soils.

It also provides food and shelter for wildlife, since some upland gamebirds and granivorous songbirds feed on its seeds. In addition, it is used as material for nest construction, and as cover for foraging animals (Hoffman, 2012).

Similarities to Other Species/Conditions

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In Illinois, USA, (Hilty, 2011) notes that Juncus interior (inland rush) and Juncus dudleyi (Dudley’s rush) are similar in appearance to J. tenuis but are usually larger plants. J. tenuis has a prominent pair of fragile, membranous lanceolate extensions (auricles) at the top of its basal sheaths. J. interior has a pair of short, soft, rounded auricles, whilst J. dudleyi has a pair of short auricles that are hard and rounded.

In New Zealand and elsewhere, J. tenuis can be confused with Juncus bufonius but plants are not easy to pull from the soil and the flower heads are less than one-quarter of the plant height: J. bufonius plants are easily pulled from the ground and the flower head often makes up two-thirds of the height of the plant (Champion et al., 2012).

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.

Control

Cultural control and sanitary measures

Mammalian herbivores typically avoid  J. tenuis as the plant material becomes stringy and tough when mature (Hilty, 2011). But sheep confined to small areas at high stocking rates can give improved control of rushes (Popay and Field, 1996). Goats provide even better control at a minimum stocking rate of 12 goats/ha.

Physical/mechanical control

The species is very resistant to trampling, cutting and grazing (Richards, 1943).

Biological control

The species does not seem to be important enough as a weed to be considered as a target for biological control.

Chemical control

Glyphosate would probably give adequate control, but adjacent grasses or other vegetation would also be damaged.

Hutto et al. (2007) evaluated the effects of 2,4-D and 2,4-D mixtures for control of J. tenuis without damaging Bermuda grass (Cynodon spp.). The best results at 15 weeks after treatment were two treatments three weeks apart in April and May (in 2003) or May and June (in 2004), with either 2,4-D ester or 2,4-D ester in mixture with mecoprop (MCPP) and dicamba. With both materials control of 95% of J. tenuis was achieved with little damage to the Bermuda grass. The authors, however, recommend additional research to verify these results. Other herbicides with apparent pre-emergence activity against J. tednuis include atrazine, simazine, halosulfuron, bentazone and imazaquine (NDR Clinic, 2016), It may be suppressed in turf and in cranberry by mesotrione (FIFRA, 2016).

Control by utilization

Sheep confined to small areas at high stocking rates can give improved control of rushes (Popay and Field, 1996). Goats provide even better control at a minimum stocking rate of 12 goats/ha. Note that Hilty (2011) warns that the plants become stringy and tough when mature, which would be more of a deterrent to sheep than to goats.

References

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Bhaumik M, 2010. Recollection of Juncus tenuis Willd. (Juncaceae) after a century from Meghalaya. Indian Forester, 136(7):993-994.

California Native Plant Society, 2016. Poverty Rush; Juncus tenuis; slender rush. Sacramento, California, USA: Californian Native Plant Society (CNPS). http://calscape.org/Juncus-tenuis-(Poverty-Rush)?srchcr=sc560cb1c497581

Champion P; James T; Popay I; Ford KA, 2012. An Illustrated Guide to Common Grasses, Sedges and Rushes of New Zealand. Christchurch, New Zealand: New Zealand Protection Society (Inc.), 182 pp.

Council of Heads of Australasian Herbaria, 2016. Australia's Virtual Herbarium., Australia: Council of Heads of Australasian Herbaria. http://avh.ala.org.au

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

FIFRA, 2016. Callisto herbicide. Section 24(C): Special local need label. EPA SLN No. MA-090001. http://www.umass.edu/cranberry/downloads/CallistoCranFinalLabel.pdf

Flora of China Editorial Committee, 2016. 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

Flora of North America Editorial Committee, 2016. Flora of North America North of Mexico. St. Louis, Missouri and Cambridge, Massachusetts, USA: Missouri Botanical Garden and Harvard University Herbaria. http://www.efloras.org/flora_page.aspx?flora_id=1

GISD, 2016. Agrostis capillaris (grass). Global Invasive Species Database. http://www.issg.org/database/species/ecology.asp?si=1365&fr=1&sts=&lang=EN

Graebner P, 1934. Juncaceae. In: Life history of flowering plants in Central Europe (Lebensgeschichte der Blutenpflanzen Mittleeuropas) [ed. by Kirchner Ov, Loew E, Schroter E]. Stuttgart, Germany: E Ulmer, 1168pp.

Hamel PB; Chiltoskey MU, 1975. Cherokee Plants and their Uses - a 400 Year History. Sylva, South Carolina, USA: Heral Publishing.

Healy AJ, 1982. Identification of Weeds and Clovers (third edition). Featherston, New Zealand: Editorial Services Limited, 299 pp.

Healy AJ; Edgar E, 1980. Flora of New Zealand. Volume III: Adventive cyperaceous, petalous & spathaceous monocotyledons. Wellington, New Zealand: Government Printer, 220 pp.

Hilty J, 2011. Path rush (Juncus tenuis). Illinois Wildflowers. Illinois, USA. http://www.illinoiswildflowers.info/grasses/plants/path_rush.htm

Hoffman RC, 2012. Plant Guide for poverty rush (Juncus tenuis). Corvallis, Oregon, USA: USDA-Natural Resources Conservation Service, Plant Materials Centre. http://plants.usda.gov/plantguide/pdf/pg_jute.pdf

Horvat G; Franjic J, 2016. Invasive plants of Kalnik forests. (Invazivne biljke Kalnickih suma.) Sumarski List, 140(1/2):53-64. http://www.sumari.hr/sumlist/pdf/201600530.pdf

Hutto KC; Taylor JM; Byrd JD, 2007. Evaluation of 2,4-D and 2,4-D mixtures for path rush control in bermudagrass. Weed Technology, 21(3):768-770. http://wssa.allenpress.com/wssaonline/?request=get-abstract&doi=10.1614/WT-07-002.1

Ishikawa H, 2010. Effects of ingestion of seeds by sika deer (Cervus nippon) and dung presence on their germination in a herbaceous community. Ecological Research, 25(3):591-598. http://www.springerlink.com/link.asp?id=112404

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

ITIS, 2016. Integrated Taxonomic Information System online database. http://www.itis.gov

IUCN, 2016. IUCN Red List of Threatened Species. http://www.iucnredlist.org/

Jurries D, 2003. Biofilters (Bioswales, Vegetative Buffers, & Constructed Wetlands) for Storm Water Discharge Pollution Removal. 52pp. http://www.deq.state.or.us/wq/stormwater/docs/nwr/biofilters.pdf

Mayer AM; Poljakoff-Mayber A, 1963. The germination of seeds. Oxford, London, New York, Paris: Pergamon Press, 243 pp.

NDRW Clinic, 2016. Herbicide Control of Juncus tenuis (Le Controle de l'Herbicide de Juncus tenuis). http://www.ndrwclinic.com/zmkbEvj/

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

Plants for Future a, 2016. Plants for a Future database. London, UK. www.pfaf.org

Pojar J; MacKinnon A, 1994. Plants of the Pacific Northwest Coast: Washington, Oregon, British Columbia and Alaska. Vancouver, British Columbia, USA: Ministry of Forests and Lone Pine Publishing.

Popay I; Field R, 1992. Grazing animals as weed control agents. Weed Technology, 10:217-231.

Preagar RL, 1934. The Botanist in Ireland. Dublin, Ireland: Figgis & Co., 587pp.

Richards PW, 1943. Biological flora of the British Isles. Juncus macer S. F. Gray. Journal of Ecology, 31:1-59.

Salisbury EJ, 1974. The reproduction of Juncus tenuis (Juncus macer) and its dispersal. Transactions of the Botanical Society of Edinburgh, 42(2):187-190.

Scully RW, 1889. Juncus tenuis in Kerry. Journal of Botany London, 27:335-336.

Stace CA, 2010. New Flora of the British Isles. Cambridge, UK: Cambridge University Press, 1232pp.

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

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

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

Varnham K, 2006. Non-native species in UK Overseas Territories: a review. JNCC Report No. 372. Peterborough, UK: Joint Nature Conservation Committee.

Wagner WI; Herbst DR; Sohmer SH, 1999. Manual of the Flowering Plants of Hawaii, revised edition. Honolulu, Hawaii, USA: University of Hawaii Press.

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Contributors

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26/04/2016 Original text by:

Ian Popay, Consultant, New Zealand

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