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

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Present on Pacific Islands?  yes

Threat only at high elevations?  no

Common name(s): [more details]

English: false oatgrass, French ryegrass, tall oatgrass

French: fenasse, fromental élevé

Spanish: fromental, 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 World Grass Species.

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) Voucher cited: Staff & 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)
Chile (continental) Chile	Chile (Republic of)		Hafliger, Ernst/Scholz, Hildemar (1980) (p. 21)
China China	China (People's Republic of)		Hafliger, Ernst/Scholz, Hildemar (1980) (p. 21)
Colombia Colombia	Colombia (Republic of)		Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. (1979) (pp. 32-33)
New Zealand New Zealand	New Zealand (country)	introduced invasive	Edgar, E./Connor, H. (2000) (p. 300)

Indian Ocean
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Mascarene Islands Mascarene Islands (Mauritius, La Reunion, Rodrigues)	Mascarene Islands	introduced invasive	U.S. Dept. Agr., Agr. Res. Serv. (2007)

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).

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

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

References:

Csurhes, S./Edwards, R. 1998. Potential environmental weeds in Australia: Candidate species for preventative control. Canberra, Australia. Biodiversity Group, Environment Australia. 208 pp.

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

Hafliger, Ernst/Scholz, Hildemar. 1980. Grass weeds, vol. 2. CIBA-GEIGY Ltd., Basle, Switzerland. 137 pp. + plates.

Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. 1979. A geographical atlas of world weeds. John Wiley & Sons, New York. 391 pp.

Starr, Forest/Starr, Kim/Loope, Lloyd L. 2003. New plant records from the Hawaiian Archipelago. In: Evenhuis, Neal L. and Eldredge, Lucius G., eds. Records of the Hawaii Biological Survey for 2001-2002. Part 2: Notes. Bishop Museum Occasional Papers. 74:23-34.

U.S. Dept. Agr., Agr. Res. Serv. 2007. National Genetic Resources Program. Germplasm Resources Information Network (GRIN). Online searchable database.

Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. 1999. Manual of the flowering plants of Hawaii. Revised edition. Bernice P. Bishop Museum special publication. University of Hawai‘i Press/Bishop Museum Press, Honolulu. 1919 pp. (two volumes).

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