Nassella tenuissima (Trin.) Barkworth, Poaceae

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Present on Pacific Islands?  no

Primarily a threat at high elevations?  no

Risk assessment results: 

Hawai‘i/Pacific:  High risk, score: 24
Risk assessment of Nawwella tenuissima from the Government of Queensland, Australia (PDF format)

Other Latin names:  Stipa tenuissima Trin.

Common name(s): [more details]

English: Argentine needlegrass, Mexican feather grass, Mexican needlegrass, Texas needlegrass, Texas tussock, angel's hair, elegant spear grass, finestem needlegrass, finestem stipa, finestem tussockgrass, pony tail, tussockgrass, white tussock

Habit:  grass

Description:  "Erect bright green perennial tussock with very narrow rolled leaves in slender shoots white at base, below a long narrow panicle with long fine intertwining awns; branching intravaginal and at nodes. Leaf-sheath to 10 cm, scabrid as leaf-blades, margins ciliate. Prophyll to 10 cm, hairy. Ligule 2.5 mm, becoming acute, minutely prickle-toothed. Leaf-blade to 60 cm x 0.3 mm diameter, terete, abaxially beset with small antrorse prickles, adaxially and on margins very finely short hairy. Culm to 1 m, internodes hairy especially below nodes, antrorsely prickle-toothed elsewhere; nodes ± geniculate. Panicle to 30 cm, contracted, much branched; rachis, branches and pedicels finely stiff hairy often densely so. Glumes unequal, violet below, hyaline above, keels sparsely finely toothed, produced to awn-like processes to 5 mm; lower to 8 mm, upper to 6 mm. Lemma 2 mm, cylindrical, slightly compressed, finely tuberculate, median nerve with long hairs, lobes minute; corona 0.4 mm, spines to 0.2 mm; awn to 50 mm, very fine (0.1 mm), weakly 2-geniculate, column lacking. Palea 0.75-1 mm, membranous, glabrous. Callus 0.2 mm, hairs to 1 mm. Lodicules 2, 0.4 mm. Anthers to 2.5 mm in chasmogamous flowers, 1 fertile anther to 0.5 mm and 2 rudimentary anthers to 0.2 mm in cleistogamous flowers. Gynoecium: ovary 0.6 mm; stigma-styles to 1.25 mm"  (Edgar & Connor, 2000; p. 81).

Description from GrassBase.

Habitat/ecology:  "Grass- and woodland, disturbed sites.  In the native range, this grass occur in grass- and shrubland, in arid woodland from near sea level to about 2,900 m elevation.  Primarily it invades disturbed grassland and becomes dominant, crowding out native vegetation and preventing the establish of native plants"  (Weber, 2003; p. 281).  "Agricultural areas, natural forests, range/grasslands, riparian zones, ruderal/disturbed, scrub/shrublands.  Grows on well drained soil and is very drought tolerant" (Global Invasive Species Database).

Propagation:  Seed.  Seeds are spread by road vehicles and also by machinery, in hay, water, mud and in the droppings of animals  (Global Invasive Species Database).

Native range:  South central United States, Mexico, Argentina, Chile (GRIN).

Impacts and invaded habitats:  In New Zealand, "Crowds out pasture species and native grasses. Very weedy in garden situations. Unpalatable to stock." (Friendly Alternatives, p. 5 [as Stipa tenuissima])

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)	New South Wales	introduced invasive cultivated	IUCN Species Survival Commission, Invasive Species Specialist Group (ISSG) (2013)
Australia Australia (continental)	Australia (continental)	introduced invasive	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Mexico Mexico	Mexico (United Mexican States)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
New Zealand New Zealand	New Zealand (country)	introduced invasive	U.S. Dept. Agr., Agr. Res. Serv. (2013)
New Zealand New Zealand	New Zealand (country)	introduced invasive	Edgar, E./Connor, H. (2000) (p. 81) Cultivated and a garden escape.
South America (Pacific rim) South America (Pacific rim)	Chile (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
United States (west coast) United States (west coast states)	USA (California)	native	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2013)
United States (west coast) United States (west coast states)	USA (California)	introduced invasive	IUCN Species Survival Commission, Invasive Species Specialist Group (ISSG) (2013)

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. (2013) Nassella tenuissima

Control: 

Physical:  "Grub (all year round): Remove soil from roots. Leave on site to rot down.

Chemical:  1. Weed wipe (dense infestations) (all year round): glyphosate (333ml/L + penetrant).
2. Spray dense spots amongst desirable broadleaved species (spring-summer): Gallant (5ml/L + crop oil).
3. Spray dense infestations only (all year round): glyphosate (15ml/L + penetrant)"  (Weedbusters New Zealand).