• Key characteristics
  • Biology
  • Impacts
  • Control
  • Further information

  • True rushes belong to the family Juncaceae. The two largest genera in New Zealand are Juncus, with 50 (including 17 native) species of wet and damp habitats and Luzula, 17 mostly native species, mostly confined to upland environments.
  • The name ‘rushes’ is widely applied to plants with a characteristic growth form – usually rhizomatous, in loose or dense clumps, with more or less cylindrical, erect, more or less rigid, sharp-tipped, leafless or with leaves like stems and basal sheaths.
  • However, some rush-like weeds (mainly of the family Cyperaceae) often grow with true rushes and can be confused with them. See Healy and Edgar’s or Champion et al’s book for further information. Two common coastal species are included in the descriptions below.
  • Here we deal only with the tall leafless or apparently leafless rushes with upright cylindrical stems which are obvious and common weeds mostly found in damper pastures. Other rushes with leaves distinctly different to the stems are not dealt with here but some will be dealt with in Rushes – II.
  • There are 20 species in this group (i.e. Rushes – I), with nine native species that include the four of the five more common species encountered.

Most important species

  • Juncus australis forms loose open clumps in pastures and damp places throughout the North and South Islands but is less common in the south of the South Island. Its clumps often have thin centres, the stems are medium-thick, blue- to grey-green, dull and ridged. Pith (the white centre of the hollow stems) is often completely absent but if the stem is cut longitudinally with a knife, the knife makes a clicking sound as it passes the hard projections on the inner walls of the stems. It is rarely grazed and then only by cattle. Native to New Zealand.
  • Juncus effusus (soft rush) is possibly the most abundant and widely distributed of all the species of leafless rushes, and occurs throughout the North and South Islands and Stewart Island, especially on peaty soils. It forms dense clumps of soft stems, readily compressed, easily broken and often grazed to the base. The pith is continuous and very spongy. The flower heads have many flowers and can be either lax or open, but the lowest branch is always curved downwards or is a dense round head. Introduced from the Northern Hemisphere.
  • Juncus edgariae can be recognised by its very dense, tall (up to 2 m) clumps of bright green, shining, wiry, slender stems and the interrupted pith of dense consistency. It is very variable in form and is very abundant and widely distributed in damp pastures and swampy places in both the North and South Islands as well as on Stewart and the Chatham Islands. This species was until recently known as Juncus gregiflorus, an Australian species, but is now recognised as unique (endemic) to New Zealand.
  • Juncus pallidus is a very tall and robust light or grey green rush up to 2 m tall. It has an uninterrupted pith and broad stems up to 8 mm across. It is native to New Zealand and is found throughout, especially in damp places near the coast.
  • Juncus sarophorus grows in very tall, dense clumps up to 2 m tall. Its stems are wiry, blue-green in colour, dull and ridged, usually with interrupted pith. The flower heads are large and fan-shaped with many slender branches pressed against the stem. It is native to New Zealand, found in damp pastures and swampy places throughout the country.

Other leafless rushes and similar species found in coastal areas

  • Juncus acutus (sharp rush) has a very scattered distribution in mostly sandy soils on the western coast of the North Island. It is a prickly upright rush forming dense clumps up to 1 m tall. Stems and leaves are light green in colour, ending in a very sharp point. Flower heads a dense cluster with distinctive large reddish-brown to brownish-orange capsules, 4.5-5 mm long.
  • Juncus kraussii (sea rush) is found in coastal areas, especially the margins of salt marshes, but also in low-lying coastal pastures in the North, South and Chatham Island but absent in the southern part of the South Island. It forms open, yellow-green clumps up to 1.2 m tall, with open black or dark brown fan-shaped flower heads.
  • Ficinia nodosa (knobby clubrush) is very rush-like but is actually a common coastal sedge found on a wide range of sandy soils. It forms dense upright clumps of shiny dark to yellow-green stems with a dense spherical dark brown flower head. It is found throughout New Zealand.
  • Apodasmia similis (oioi) is a jointed rush (a family related to the true rushes), with characteristic dark joints (actually reduced leaves) regularly spaced wiry, dull grey-green or yellow dense stems often flowering at the tips. This species typically forms dense beds (up to 1.5 m tall) rather than individual clumps. It is a characteristic salt marsh plant also found in other wet coastal areas, found throughout and unique (endemic) to New Zealand.

Origin

  • There are 20 species in this group of leafless or apparently leafless rushes in New Zealand and all but one have been introduced, presumably accidentally, from elsewhere, mostly from Australia but also from North or South America, Eurasia or Africa.

Life Cycle

  • Most species flower between November and January and seed is set from January to February
  • Seeds are small and dust-like. They can remain viable but dormant in the soil for up to 60 years. Moist stratification can facilitate seed germination
  • Seeds are distributed by wind, water or animals
  • Seeds probably most commonly germinate in spring and autumn, whenever conditions of temperature and moisture are favourable.

Benefits

  • Rushes have long been used in many parts of the world for weaving into chair bottoms, mats, and basketwork, and the pith has served as wicks in open oil lamps and for tallow candles (rushlights)
  • Some rushes are used in reclamation projects or in wetland construction. An improved cultivar of Juncus effusus (Sumter Germplasm soft rush) has been released by the Jimmy Carter Plant Materials Center in the USA for small constructed wetlands, wetland restoration and riparian buffers.

  • Leafless rushes are a very common and obvious problem to New Zealand farmers, especially in seasonally wet pastures. They have long-lived seed that can respond to wet seasons and they can establish in heavily grazed pastures due to their low stock palatability
  • They affect the productivity of pastures by reducing grazing areas. A 15% infestation of rushes can reduce dry matter by 1.25 tonne/ha.

Cultural control

    Methods can involve improved drainage, liming and/or disking/ploughing and reseeding with competitive grass species. Preventing overgrazing of wet paddocks will assist in preventing reestablishment of rushes.

  • Mowing only provides temporary control of rushes.

Chemical control

  • 2,4-D ester is registered for rush control. Recommendations are to mow the rushes and spray when 30-40 cm tall using 8 L of 520 g a.i./L formulations in 200 L of water/ha boom spraying
  • Glyphosate formulations give good but non-selective control in pastures. However, wick wiper applications taking advantage of the much taller rush clumps can be effective, timed from November to May. A mixture of one part 360 g a.i. formulation to two parts water is recommended, with a double pass in opposite directions recommended. Conversely, glyphosate can be used for pasture renovation followed by reseeding and pasture management described above.

Bodmin KA, Champion PD, James TK, Burton T, 2016. New Zealand rushes (Juncus): factsheets and key.

Champion P, James TK, Popay AI, Ford K, 2015. An Illustrated Guide to Common Grasses, Sedges and Rushes of New Zealand. New Zealand Plant Protection Society, Christchurch, New Zealand.

Healy AJ, 1982. Rushes. Pp. 129-172, in Healy AJ, Identification of Weeds and Clovers, A New Zealand Weed and Pest Society Publication, Editorial Services, Featherston. (Book no longer in print and hard to find in second-hand bookshops).

Healy AJ, Edgar E, 1980. Flora of New Zealand Volume III, Adventive Cyperaceae, Petalous and Spathaceous Monocotyledons. PD Hasselberg, Government Printer, Wellington, New Zealand. (Book no longer in print but may be available from second-hand bookshops).