Spiny Rush
Juncus acutus L.

Family: - Juncaceae.

Names:

Juncus is probably from the Latin junctio meaning joining and refers to the use of rushes for weaving baskets and mats.

Acutus is the Latin word meaning pointed and refers to the sharp, pointed leaves and bracts on this species.

Spiny Rush because its very spiny.

Other names:

Sharp Rush (NZ)

Sharp-pointed Rush (Europe)

Summary:

A hemispherical, 1 m diameter, hedgehog like perennial tussock with compound, brown, globular flower heads a few centimetres from the stem tip. It is salt tolerant.

Description:

Cotyledons:

One.

First leaves:

Hollow, fleshy. Tip pointed. No ligule or auricles. Seed coat often attached to tip of leaf.

Leaves:

Similar to stems but with no flower heads. Dark green, cylindrical, up to 500 mm long, tapering to a very sharp spine. Leaves emerge from the base at angles giving the plant a hemispherical shape. Filled with continuous pith with no partitions (not septate). Sheathed at the base. May emerge from the root system or the base of stems.

Stems:

Tussocky, dark green, many, arising from rhizomes, unbranched, up to 2000 mm long by 3-5 mm diameter, cylindrical, rigid, smooth, faintly furrowed, filled with continuous white pith. Unbranched. Hairless. Tapering to a very sharp spine. Stems arise at all angles to make a hemispherical plant.

Flower head:

Panicle like, compound, with several dense, almost round, 3 mm diameter, flower clusters on spreading branches with a broad, long sharply-pointed bract underneath that appears as a continuation of the stem. Arises from the side of the stem near the top.

Flowers:

Perianth - Green turning to reddish-brown at maturity. Very small, stalkless. Segments 2.5-4 mm long, pointed, shorter than the capsule.

Stamens - 6.

Anthers -

Fruit:

Brown, shiny, egg shaped to oval, 3-celled capsule, 5 or 6mm long, pointed at the tip.

Seeds:

Brown, 1 mm long or less, many in each capsule, oval to irregularly shaped, with papery appendages and tailed at both ends usually.

Roots:

Shallow, fibrous root mat with short, stout rhizomes forming large tussocks.

Key Characters:

Leaf blades cylindrical, non septate and similar to the stem. Primary bract apparently continuous with the stem. Compact inflorescence appears lateral. Perianth segments as long as the capsule.

Biology:

Life cycle:

Long lived perennial reproducing by seed and rhizomes. Seeds germinate any time of the year. Young plants do not flower in their first year or until a perennial crown and rhizomes have developed. New growth, which appears mainly in spring and summer, replaces the few leaves and stems that have died in the preceding season.

Physiology:

Salt tolerant.

Reproduction:

By seed, rhizomes and fragments of crowns and rhizomes.

Flowering times:

Spring and summer in western NSW.

Throughout the year in SA.

Seed Biology and Germination:

Vegetative Propagules:

Crown and rhizome fragments.

Hybrids:

Allelopathy:

Population Dynamics and Dispersal:

Dispersal of seeds is by water, contamination of agricultural produce, machinery, mud. Seed capsules float and are spread effectively by water. Fragments of crown and rhizome moved by cultivation can form new plants.

Often occurs initially in and adjacent to waterways and spreads on to neighbouring pastures where it is ignored by stock. It requires wet soils to establish but persists through extended dry periods.

Origin and History:

Mediterranean region. Western Europe. Western North America. South America. Southern Africa. May also be native to Australia.

Distribution:

NSW, SA, VIC, WA.

Habitats:

Climate:

Humid or sub-humid temperate regions.

Soil:

Often in low-lying, damp, low fertility areas, saline soils and coastal flats.

Plant Associations:

Significance:

Beneficial:

Colonising plant on mine dumps.

Leaves have been used to weave baskets, mats chair seats.

Pith has been used for lamp and candle wicks.

Detrimental:

Weed of pasture, wetlands irrigation channels, coastal flats, mine dumps, disturbed saline areas and roadsides.

Impedes water flow in drains and channels and cause serious flooding. Once established can completely cover an area and eliminate almost all other vegetation and exclude stock and people due to sharp spines. This prevents poor country from being improved and provides a source of seeds to infest other areas.

It is not generally eaten by stock apart from young fresh growth, which is occasionally eaten when exposed.

It can prevent stock access to water along streams.

Harbours vermin, especially rabbits as dogs will not work in the spines and burrows cannot be ripped.

Toxicity:

Unknown toxicity.

Legislation:

Noxious in Victoria.

Management and Control:

Good drainage aids control. Chemical control results mixed, often impractical on dense patches. Mechanical removal is often the most practical starting point in a control program. A heavy tractor with blade is often used. Specialised units are more effective and efficient, eg. Yacka cutter fitted to the 3-point linkage of a tractor and cutting just below ground level, results depend on operator skills, soil type (sandy best) and moisture level (dry best); 'stone bucket' fitted to the arms of a front-end leader and driven into patches with plants heaped and burnt when bucket full; chisel ploughs, or heavy mould-board ploughs or blade ploughs. Plants must be heaped and burnt and cleared areas cultivated to encourage seedlings and regrowth then recultivated extending over two summers then sown with a pasture mixture or other suitable permanent vegetation. Flame throwers have also been used to remove top growth so that crowns and rhizomes may be more effectively controlled by cultivation.

Hexazinone is the preferred herbicide as an overall spray or as a concentrate to the soil near each plant using the 'spot gun' technique.

Thresholds:

Eradication strategies:

Herbicide resistance:

Biological Control:

Related plants:

Blunt flowered Rush (J. subnodulosus)

Bulbous Rush (J. bulbosus)

Common Rush (J. usitatus)

Dwarf Rush (J. capitatus)

Giant Rush (J. ingens)

Jointed Rush (J. articulatus)

Jointed Rush (J. holoschoenus)

Pale Rush (J. pallidus)

Sea Rush (J. kraussii)

Toad rush (J. bufonius)

Tussock Rush (J. aridicola)

(J. effusus)

Plants of similar appearance:

References:

Auld, B.A. and Medd R.W. (1992). Weeds. An illustrated botanical guide to the weeds of Australia. (Inkata Press, Melbourne). P28-29. Photos.

Black, J.M. (1978). Flora of South Australia. (Government Printer, Adelaide, South Australia). P322.

Cunningham, G.M., Mulham, W.E., Milthorpe, P.L. and Leigh, J.H. (1992). Plants of Western New South Wales. (Inkata Press, Melbourne). P176. Photo.

Hussey, B.M.J., Keighery, G.J., Cousens, R.D., Dodd, J. and Lloyd, S.G. (1997). Western Weeds. A guide to the weeds of Western Australia. (Plant Protection Society of Western Australia, Perth, Western Australia). P38. Photo.

Lamp, C. and Collet, F. (1990). A Field Guide to Weeds in Australia. (Inkata Press, Melbourne). P148.

Lazarides, M. and Hince, B. (1993). CSIRO handbook of economic plants of Australia. (CSIRO, Melbourne). #703.1.

Moerkerk, M.R. and Barnett, A.G. (1998). More Crop Weeds. R.G. and F.J. Richardson, Melbourne. P22. Diagrams. Photos.

Parsons, W.T. and Cuthbertson, E.G. (1992). Noxious weeds of Australia. (Inkata Press, Melbourne). P81-84. Photos.

Acknowledgments:

Collated by HerbiGuide. Phone 08 98444064 or www.herbiguide.com.au for more information.