Spiny rush (Juncus acutus) is a long-lived perennial herb. Also known as sharp rush, it competes with native biodiversity and can be damaging to stock.
- grows to 2m x 2m
- globe-like with numerous cylindrical, flowering stems 3-5mm in diameter
- dark green leaves are cylindrical, 3-5mm in diameter, tapering to rigid sharp spines
- flowers are green to reddish brown in a rounded, stalked cluster 30mm in diameter
- ripe fruits are ovoid nut-like capsules with a short point at one end from which a small papery protrusion is visible
- mass of shallow fibrous roots.
Why is it a problem?
- highly unpalatable to stock and sharp spines can cause injury
- competes with preferred pasture plants and reduces carrying capacity of land
- restricts movements of animals, machinery and humans
- harbour for vermin
- increases the potential for floods due to restricted water flow.
- South Australia: Adelaide Plains; Mount Pleasant; lower Eyre Peninsula; Mount Remarkable; Kangaroo Island; River Murray floodplain; Riverland (including Loveday Swamp); Coorong; near Kingston; Beachport; South East
- Common and widespread in eastern and southern New South Wales, the ACT, Victoria, and south-western Western Australia
- A threat to arid wetlands in the Northern Territory where populations have spread along the Finke River between Ormiston and Finke Gorge.
- prefers pasture, coastal flats, moist low-lying regions and disturbed infertile areas such as mine dumps
- thrives in areas of high salinity
- plants do not flower until at least two years old
- two native species are often confused with spiny rush – knobby club rush (Isolepis nodosa) and sea rush (Juncus kraussii).
How it spreads
- principally dispersed via water, along drainage channels and creek lines
- seeds contaminate agricultural produce, and adhere to machinery and vehicles via mud and soil
- can also establish as a result of cultivation, or physical or mechanical disturbance.