Juncus acutus L., Juncaceae

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Present on Pacific Islands?  no

Primarily a threat at high elevations?  no

Risk assessment results:  Reject, score: 15 (Go to the risk assessment)

Common name(s): [more details]

English: sharp rush, spiny rush

Habit:  rush

Description:  "Very stout, forming dense prickly tufts; rhizomes stout, woody. Stems (40) -60-100cm x 1.5-5 mm, very stiff and erect, smooth, light green. Basal sheaths shining dark red-brown. Leaves 1-2, basal, terete, similar to stem, with very pungent tip. Inflorescence large, compact 5-15 cm long. Flowers crowded. Tepals c. 3 mm long, ± equal, very hard, outer mucronate, inner truncate to emarginate with wide membranous margin at tip. Stamens 6. Capsule 4.5-5 mm long, much > tepals, ovoid, abruptly tapered, acute, reddish-brown to brownish-orange. Seeds with distinct tails.  Recognised by the dense, robust, stiff, prickly clumps, large congested heads, large reddish-brown to brownish-orange capsules much > tepals, and long-tailed seeds"  (Healy & Edgar, 1980; p. 99).

Habitat/ecology:  "Coastal flats and saline areas, grassland, riparian habitats, disturbed sites.  Native habitats of this plant include sandy seashores, drier parts of salt marshes, and other sandy places.  It is a highly variable species with numerous varieties.  The large and dense tussocks lead to dense patches that support little native vegetation.  In infested watercourses, the plant restricts water flow"  (Weber, 2003; p. 223).

In the United States, "moist saline habitats and alkaline seeps; below 300 m"  (Flora of North America online).  Coastal saline flats where naturalized in New Zealand  (Healy & Edgar, 1980; p. 99).

Propagation:  "Seeds are dispersed mainly by water"  (Weber, 2003; p. 223).

Native range:  Northern Africa, Europe, western Asia, southwestern USA, northern Mexico; naturalized in Australia, New Zealand & southern South America (GRIN).

Presence:

Pacific Rim
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Australia Australia (continental)	Australia (continental)	introduced invasive	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Mexico Mexico	Mexico (United Mexican States)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
New Zealand New Zealand	New Zealand (country)	introduced invasive	U.S. Dept. Agr., Agr. Res. Serv. (2011)
United States (west coast) United States (west coast states)	USA (California)	native	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2011)

Also reported from
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
United States (continental except west coast) United States (other states)	United States (other states)	native	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2011)

Control: 

Physical:  "Single tussocks may be removed mechanically.  Cutting at ground level is used for larger infestations, and a follow-up programme is necessary to control regrowth and emerging seedlings".

Chemical:  "Effective herbicides are 2,4-D ester or hexazinone"  (Weber, 2003; p. 223).

Additional information:
Additional online information about Juncus acutus is available from the Hawaiian Ecosystems at Risk project (HEAR).

Information about Juncus acutus as a weed (worldwide references) may be available from the Global Compendium of Weeds (GCW).

Taxonomic information about Juncus acutus may be available from the Germplasm Resources Information Network (GRIN).

References:

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

U.S. Dept. Agr., Agr. Res. Serv. 2011. National Genetic Resources Program. Germplasm Resources Information Network (GRIN). Online searchable database.

U.S. Dept. Agr., Nat. Res. Cons. Serv. 2011. The PLANTS Database. National Plant Data Center, Baton Rouge, LA 70874-4490 USA.

Weber, Ewald. 2003. Invasive plants of the World. CABI Publishing, CAB International, Wallingford, UK. 548 pp.