Eleusine tristachya (Lam.) Lam., Poaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Other Latin names:  Cynosurus tristachyos Lam.

Common name(s): [more details]

English: American yard-grass, threespike goosegrass, threespike grass

Habit:  grass

Description:  "Perennial; short-lived; caespitose. Culms geniculately ascending, or decumbent; slender; 10-45 cm long. Culm-internodes elliptical in section. Leaves mostly basal. Leaf-sheaths keeled; outer margin glabrous. Ligule a ciliolate membrane. Leaf-blades 6-25 cm long; 1-4 mm wide. Inflorescence composed of racemes. Racemes 2-3; digitate; linear, or oblong; unilateral; 1-4 cm long; 10-16 mm wide. Rhachis broadly winged; with rounded midrib. Spikelet packing broadside to rhachis. Spikelets appressed; solitary. Fertile spikelets sessile. Fertile spikelets: Spikelets comprising 6-13 fertile florets; with diminished florets at the apex. Spikelets ovate; laterally compressed; 5-9 mm long; 4-6 mm wide; breaking up at maturity; disarticulating below each fertile floret. Glumes persistent; similar; shorter than spikelet; similar to fertile lemma in texture. Lower glume lanceolate; 1.5-2 mm long; 0.5 length of upper glume; membranous; 1-keeled; 1-3 -veined. Lower glume apex acute. Upper glume elliptic; 3-4 mm long; 0.7-0.8 length of adjacent fertile lemma; membranous; 1-keeled; 5-7 -veined. Upper glume apex acute. Florets: Fertile lemma ovate; 4-5 mm long; membranous; keeled; 3 -veined (excluding subsidiaries). Lemma midvein with contiguous subsidiary veins (3-veined). Lemma apex acute. Palea 0.66 length of lemma; 2 -veined. Apical sterile florets resembling fertile though underdeveloped. Flower: Lodicules 2; cuneate; fleshy. Caryopsis with free soft pericarp; orbicular; isodiametric; trigonous; concealed by floret; 2 mm long; dark brown; rugose. Embryo 0.3-0.4 length of caryopsis. Hilum punctiform"  (GrassBase).

Description from the Flora of New Zealand.

Habitat/ecology:  In New Zealand, "waste land, lawns and golf courses"  (Edgar & Connor, 2000; p. 523).  In Australia, "weed of disturbed ground and extensive mown areas"  (NSW PlantNET).

Propagation:  Seed

Native range:  Argentina, Bolivia, Brazil, Chile, Paraguay, Uruguay; naturalized elsewhere (GRIN).

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Chile (offshore islands) Juan Fernández Islands	Isla Más a Tierra (Robinson Crusoe Island)	introduced invasive	Atkinson, Rachel/Sawyer, John (2011)
Chile (offshore islands) Juan Fernández Islands	Isla Más a Tierra (Robinson Crusoe Island)	introduced invasive	Danton, Philippe/Perrier, Christophe/Martinez Reyes, Guido (2006) (pp. 461, 465, 553)
Chile (offshore islands) Juan Fernández Islands	Isla Más Afuera (Alejandro Selkirk Island)	introduced invasive	Atkinson, Rachel/Sawyer, John (2011)
Chile (offshore islands) Juan Fernández Islands	Isla Más Afuera (Alejandro Selkirk Island)	introduced invasive	Danton, Philippe/Perrier, Christophe/Martinez Reyes, Guido (2006) (pp. 461, 465, 553) Voucher cited: Danton G(1432)1197

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	National Herbarium of New South Wales (2011)
Australia Australia (continental)	Queensland	introduced invasive	National Herbarium of New South Wales (2011)
Chile (continental) Chile	Chile (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
New Zealand New Zealand	New Zealand (country)	introduced invasive	Edgar, E./Connor, H. (2000) (p. 523)
United States (west coast) United States (west coast states)	USA (Oregon)	introduced	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2011)
United States (west coast) United States (west coast states)	USA (California)	introduced	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)	introduced	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2011)

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

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

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

References:

Atkinson, Rachel/Sawyer, John. 2011. Naturalized species in the Juan Fernández Archipelago, Chile. Unpublished spreadsheet.

Clayton, W.D./Harman, K.T./Williamson, H. 2011. World Grass Species: Descriptions, Identification, and Information Retrieval [GrassBase - The Online World Grass Flora]. The Board of Trustees, Royal Botanic Gardens, Kew.

Danton, Philippe/Perrier, Christophe/Martinez Reyes, Guido. 2006. Nouveau catalogue de la flore vaculaire de l'archipel Juan Fernández (Chile) [Nuevo catálogo de la flora vacular del Archipélago Juan Fernández (Chile)]. Acta Bot. Gallica 153(4):399-587.

Edgar, E./Connor, H. 2000. Flora of New Zealand, vol. V: Gramineae. Manaaki Whenua Press. .

National Herbarium of New South Wales. 2011. PlantNet: New South Wales Flora online. The Plant Information Network System of the Botanic Gardens Trust Version 2.0. Online resource.

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.