Quick Facts

Quick facts

• Originally from Europe, Africa, Asia and the Americas, Spiny Rush (Juncus acutus subsp. acutus) is dense large dense hemispherical tufted deep green plant to 1-5-2 metres tall.
• A weed of damp areas in temperate regions in southern Australia, extending up the coast of NSW to south-east Queensland, and also found in the NT around Alice Springs.
• Its leaves and flower stems ends are very sharp, hard points that can pierce the skin and injure animals.
• It is a serious weed because of its abundant seed production and very pointed tips, which make control difficult.
• Once established, it out-competes other species and becomes the dominant vegetation cover and therefore a serious environmental and agricultural weed.
• Dense infestations of large plants can inhibit the movement of people and animals including livestock. 
• Spreads mostly by seed transport via water ways and and by people on machinery, soil . 
• Can be controlled with herbicides, but hand pulling small plants possible, and mechanical control used for large dense infestations. 
• Follow up is required for 2-4 years to prevent establishment of seedlings. 

What Does It Look Like?

What is it?

Spiny Rush (Juncus acutus subsp. acutus) is a tough, dense, tussock-forming perennial rush with a very short rhizome (underground stem). Its stems are both leaves and culms (culms; stems bearing the clusters of flowers) both are very similar in appearance, terete (round in cross-section), blue-green or dark green,  a very sharp pointed tip when mature. Stems have a continuous dense, uninterrupted pith permeated with vascular bundles (visible in transverse section).  Culms 30–160 cm long, 2-4 mm in diameter, 30–150 cm high, each culm with to 2–5 leaves and leaves and culms with several mid to dark brown shining cataphylls (an enlarged leaf-sheath, a scale leaf) toward base. Leaves and culms emerge from the base of the tussock at an angle, giving the plant a hemispherical shape.

The flowers are borne in dense branching clusters, normally in a single dense cluster but sometimes stem seem between some clusters, mainly about 4–13 cm long  and normally not as wide. Flowers clustered, 1–6 per cluster, and 5–50 clusters per inflorescence, greenish, brown or reddish-brown and. Individual flowers are small, inconspicuous and almost stalkless. 

The fruit is a brownish coloured capsule, darker in upper half, 4–6 mm long, ovoid (oval) to ellipsoid (egg-shaped, widest at the base) normally shiny, with a pointed apex (top). The tepals (the outer whorls or non-fertile parts surrounding the capsule), only cover the bottom half of the capsule, with the shiny capsule visible. Each capsule contains many oval or irregularly shaped seeds, about 1 mm long (Wilson et al. 1993; Parsons & Cuthbertson 2001; Navie 2004).

Recognition: This species can normally be recognised by the combination of the following characters; very sharp point stiff stem leaves (both flowering stems and leaves) that have continuous pith, and the tepals that only cover the bottom half of the capsule, with the shiny capsule visible.

For further information and assistance with identification of Spiny Rush contact the herbarium in your state or territory.

Flower colour

Green, Brown

Growth form (weed type/habit)

Herb

Where it currently grows? Preferred habitat

Spiny Rush usually grows in humid or sub-humid temperate regions, on disturbed areas at low altitude, such as roadsides, eroded gullies, pastures and over-grazed stream-banks, often in brackish or salt-affected areas (Wilson et al. 1993; Parsons & Cuthbertson 2001; Hodgon 2006). Spiny rush prefers calcareous soils. It is principally dispersed via water, along drainage channels and creek lines and as such is found by fresh and saline areas such as coastal saltmarshes and inland depressions, frequently associated with ends of irrigation systems (Sainty & Jacobs 2003). Spiny Rush can colonise mine dumps and other areas of low fertility, and once established it does not require permanently wet soil in order to persist (Cunningham et al. 1992).

Are there similar species?

There are many species of rushes (Juncus spp.) and also some sedges (Cyperus spp. and Carex spp.) that are similar to Spiny Rush. Spiny Rush can usually be distinguished from these by its very sharply pointed stems and leaves (Navie 2004). 

Spiny Rush can be distinguished from the native species Juncus kraussii (which grows in brackish situations like saltmarshes) by its more robust, hemispherical tussocks (narrower, erect clumps in Juncus kraussii). Spiny rush has ripe fruits (seed capsules) that are only half covered by the tepals and are shiny, while Juncus kraussii  seed capsules are covered to emclosed by the tepals.

It differs from the most common erect native species like J. polyanthemus and J. usitatus in having long leaf blades – those native species have the leaf blade reduced to a tiny point on the leaf sheath (Wilson et al. 1993).

Why Is It A Weed?

What are its impacts?

Spiny Rush is an agricultural and environmental pest able to tolerate both saline and fresh water and wet or dry conditions (Hodgon 2006), in open areas of wetlands, swamps and creeks with elevated salinity levels, including coastal flats. It also invades pastures and disturbed sites such as mine sites and dumps. It is capable of completely covering large areas in both agricultural, disturbed and in some undisturbed environments, preventing regeneration (Hodgon 2006). Once established, eliminates all other vegetation, makes areas impenetrable because of the sharp spines for larger animals and people.

Agriculture: Spiny Rush reduces the productivity of pasture areas by competing with preferred pasture plants and soon dominates as it is not readily eaten by grazing animals. It can also spread to impede water flow in drains and channels (Sainty & Jacobs 1981; Auld & Medd 1992; Cunningham et al. 1992), with serious obstruction able to cause flooding (Anderson et al. 1998; Parsons & Cuthbertson 2001).  Dense thickets also prevent access to water by livestock (Anderson et al. 1998), and the sharp points at the ends of the stems and leaves are capable of causing serious injury (Hodgon 2006; & Cuthbertson 2001). Stands also provide an effective harbour for pest animals such as rabbits (Cunningham et al. 1992; Anderson et al. 1998; Parsons & Cuthbertson 2001).

Native ecosystems: Establishes in intact and disturbed natural ecosystems such as riparian vegetation and wetland areas.  Spiny Rush is not readily eaten by native grazing animals, and once established it can cover large areas eliminating and excluding other vegetation (Auld & Medd 1992; Cunningham et al. 1992; Anderson et al. 1998; Parsons & Cuthbertson 2001). 

Human impacts: The sharp spines are a hazard to people, particularly to eyes, and are especially dangerous to children (Thorp & Wilson 1998 -).

How does it spread?

Spiny Rush spreads by short rhizomes, but is spread mostly by seeds. The short rhizomes can be dispersed in soil attached to vehicles or animals (Hodgon 2006). Its abundant small seeds are distributed by moving water (which results in much spread along waterways), as well as by agricultural and mining machinery, birds, stock and other animals (Anderson et al. 1998; Parsons & Cuthbertson 2001; Sainty & Jacobs 2003; Ermert 2006; Hodgon 2006). 

What is its history in Australia?

It is not known how Spiny Rush arrived in Australia. The earliest herbarium specimens were collected in the Sydney area (Wilson 2008 pers. comm.) and on the banks of the Loddon River in Victoria in 1909 (AVH 2021). It was recorded in South Australia in 1919. Recorded much later in the other states; 1957 from Western Australia;  1996 from the Northern Territory; 1998 from Tasmania; 2001 from Queensland.

How To Manage It?

Best practice management

Spiny Rush is very difficult to eradicate once it is established. It has the potential to be a troublesome weed in some places and should be controlled as early as possible. As with many weeds, controlling infestations early and preventing further spread will be the most effective form of management (Sainty & Jacobs 1981). Spiny Rush management programs using mechanical controls, chemicals, cultivation, altering salinity and drainage, and pasture management measures have been proposed (Anderson et al. 1998; Parsons & Cuthbertson 2001). 

Non-chemical control: Even quite small plants can require a large amount of effort to remove (Sainty & Jacobs 2003); however, small stands of Spiny Rush may be dug out effectively, as the plant is shallow-rooted. The roots need to be severed and the top growth may also be burnt if seed is present.  Because the plant likes damp situations, improving drainage may help to reduce populations, but this would not be a suitable control measure where it is a weed in natural habitats such as wetlands (Ermert 2001). Machinery is used to cut spiny rush just below the ground surface. After physical removal,plants are heaped and burnt, and thenthe soil is cultivated to encourage the growth of seedlings. Follow-up cultivation over the following two summers are necessary to destroy seedlings, although some seed will remain to germinate in following years.Burning or slashing and then spraying or wiping new growth with herbicide can increase herbicide uptake, making the treatment more effective. (Government of South Australia 2021). 

Chemical control: Chemicals are not considered to be very successful in the reduction of Spiny Rush (Ermert 2001), but can be used to some effect in association with other control measures. Chemical control is often impractical because of the difficulty of application to dense patches; therefore, mechanical removal of the existing growth, although costly, is often the most practical starting point in a control program (Parsons & Cuthbertson 2001).

Please see the Australian Pesticides and Veterinary Medicines Authority for chemical information http://www.apvma.gov.au 

Does it have a biological control agent?

NO

When does it grow? (lifecycle/growth calendar)

Spiny Rush is a long-lived perennial. Young plants do not flower until at least two years old (Parsons & Cuthbertson 2001). Flowering and seed germination can occur at any time of year (Hodgon 2006), but Spiny Rush flowers mainly in spring or summer (Sainty & Jacobs 1981). Ripe fruit can be found virtually all year (Albrecht & Walsh 1994).

Where Is It Found?

Which states and territories is it found?

NSW, NT, QLD SA, TAS, VIC, WA

What areas within states and territories is it found?

Spiny Rush is naturalised in southern Australia inNew South Wales, Victoria, South Australia, Tasmania and Western Australia) and up the east coast of New South Wales in to south -east Queensland (AVH 2021). It also is around Alice springs in the Northern Territory in areas that are annually wet by rivers, lakes, creeks drains and similar areas. 

Where does it originate?

The origin of Spiny Rush is obscure, but it is thought to have a wide native range including the Mediterranean region, western Europe, western North America, South America, Asia and southern Africa. (Parsons & Cuthbertson 2001; Navie 2004).

National And State Weed Listings

Is it a Weed of National Significance (WONS)?

NO

Where is it a declared weed?

SA, VIC

Government weed strategies and lists – Weeds Australia

Is it on the National Alert List for Environmental Weeds?

NO

Government weed strategies and lists – Weeds Australia

Is it on the Agricultural Sleeper List?

NO

Government weed strategies and lists – Weeds Australia

Names And Taxonomy

Main scientific name

Juncus acutus subsp. acutus

Other scientific names (synonyms)?

Does it have other known common name(s)?

Sharp Rush, Sharp-pointed Rush, Cultivation Rush