Arrhenatherum elatius (L.) Mert. & Koch, Poaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Other Latin names:  Arrhenatherum avenaceum (Scop.) P. Beauv.; Avena bulbosa Willd.; Avena elatior L.

Common name(s): [more details]

Chinese: yan mai cao

English: French ryegrass, French-rye, bulbous oatgrass, false oatgrass, meadow oat grass, onion couch, onion twitch, onion-root twitch, tall oatgrass, tuber oat grass

French: avoine élevée, fenasse, fromental, fromental élevé

Japanese: ō-kani-tsuri

Spanish: fromental, mazorilla, raygras Françés

Habit:  grass

Description:  "Loosely tufted, coarse perennials, (40)-60-150 cm. Leaf-sheath ± chartaceous, smooth, or rarely minutely scabrid, sometimes with scattered long fine hairs. Ligule 1-3-(4) mm, truncate to ± obtuse, erose, ± ciliate, abaxially minutely scabrid to minutely hairy. Leaf-blade 15-30-(50) cm x 2-12 mm, minutely scabrid on ribs, to ± smooth, adaxially often with scattered long fine hairs; margins minutely, closely scabrid, tip acute, scabrid. Culm erect or ± spreading, stout. Panicle (4)-14-32 cm, erect or nodding, dense or lax, slender and lanceolate or with lower branches spreading; rachis smooth below, scabrid above, branches and pedicels slender, scabrid. Spikelets 7.5-9.5-(11) mm, shining, green or purplish. Glumes acute, sometimes finely scabrid, nerves finely scabrid; lower (3.5)-4.5-6-(6.8) mm, lanceolate, 1-nerved, upper ≤ spikelet, ovate-lanceolate, 3-nerved. Lemma (7)-8-9 mm, 7-nerved, ovate-lanceolate, hyaline near acute tip, nerves distinct, finely scabrid, upper or both lemmas with scattered fine hairs in lower 1/2; awn of lower lemma 8-16.5 mm; awn of upper lemma 0.5-10 mm, or 0. Palea narrower than lemma, keels finely ciliate, interkeel minutely scabrid, apex shortly bifid. Callus usually ringed by short stiff hairs. Rachilla prolongation 1.5-2.5 mm, delicate, glabrous. Anthers 3.5-5 mm. Gynoecium: ovary 0.6-0.8 mm; stigma-styles 1.5-1.8 mm. Caryopsis 2.5-3.8 x 0.8-1.2 mm"  (Edgar & Connor, 2000; p. 300).

Description from GrassBase.

Habitat/ecology:  "Floodplains, riparian habitats, damp places.  This grass grows best in moist soils... Dead shoots are highly flammable and the grass resprouts quickly after burning.  The plant forms species poor clones that may cover hundreds of acres and displace native vegetation and exclude associated wildlife species"  (Weber, 2003; p. 57).

In New Zealand, "Along roadsides and railway lines, on clay banks, in waste ground, paddocks and sometimes on dune margins, or a garden weed; sea level to montane"  (Edgar & Connor, 2000; p. 300).

Propagation:  "Spreads mainly by stem and rhizome fragments.  In North America, no viable achenes are formed.  Even small rhizome fragments can regrow and form new plants; rhizome fragments are carried by rivers and streams"  (Weber, 2003; p. 57).

Native range:  Canary Islands, northern Africa, Europe, western Asia (GRIN).

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
State of Hawaii Hawaiian Islands	Hawai‘i (Big) Island	introduced invasive	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 1482) Voucher cited: Hosaka 1553 (BISH)
State of Hawaii Hawaiian Islands	Maui Island	introduced invasive	Starr, Forest/Starr, Kim/Loope, Lloyd L. (2003) (p. 29) East Maui. Voucher cited: Starr & Martz 010721-2 (BISH)

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	Csurhes, S./Edwards, R. (1998) (pp. 142-143)
Australia Australia (continental)	Queensland	introduced invasive cultivated	Csurhes, S./Edwards, R. (1998) (pp. 142-143)
British Columbia (province of Canada) Province of British Columbia	Canada (British Columbia)	introduced	U.S. Dept. Agr., Agr. Res. Serv. (2013)
China China	China (People's Republic of)	introduced cultivated	Zhengyi, Wu/Raven, Peter H./Deyuan, Hong (2013) "Introduced to China as an ornamental garden plant and for forage".
Japan Japan	Japan	introduced	Mito, Toshikazu/Uesugi, Tetsuro (2004) (p. 192) var. biaristatum Peterm, var. bulbosum Spenner, var. elatiusglabrescens Celakovsky, var. nodosum and var. subhirsutum Ascherson
New Zealand New Zealand	New Zealand (country)	introduced invasive	Edgar, E./Connor, H. (2000) (p. 300)
South America (Pacific rim) South America (Pacific rim)	Chile (Republic of)		Hafliger, Ernst/Scholz, Hildemar (1980) (p. 21)
South America (Pacific rim) South America (Pacific rim)	Colombia		Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. (1979) (pp. 32-33)
United States (west coast) United States (west coast states)	USA (Oregon)	introduced	U.S. Dept. Agr., Agr. Res. Serv. (2013)
United States (west coast) United States (west coast states)	USA (California)	introduced	U.S. Dept. Agr., Agr. Res. Serv. (2013)
United States (west coast) United States (west coast states)	USA (Washington)	introduced	U.S. Dept. Agr., Agr. Res. Serv. (2013)

Indian Ocean
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
La Réunion (France) La Réunion Island	La Réunion Island	introduced invasive	U.S. Dept. Agr., Agr. Res. Serv. (2013) Naturalized
Mauritius Mautitius Islands (Mauritius and Rodrigues)	Mauritius Island	introduced invasive	U.S. Dept. Agr., Agr. Res. Serv. (2013) Naturalized

Also reported from
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Canada Canada	Canada	introduced	U.S. Dept. Agr., Agr. Res. Serv. (2013)
United States (continental except west coast) United States (other states)	United States (other states)	introduced	U.S. Dept. Agr., Agr. Res. Serv. (2013)

Control: 

Physical:  "Repeated cutting reduces vitality.  In the western USA, a late spring mowing with removal of cut material is recommended over a period of at least 3 years".

Chemical:  "Smaller patches can be sprayed with grass-selective or non-selective herbicides"  (Weber, 2003; p. 56).