Echinochloa polystachya (Kunth) Hitchc., Poaceae

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Present on Pacific Islands?  yes

Threat only at high elevations?  no

Risk assessment results:  Reject, score: 13 (Go to the risk assessment)

Other Latin names:  Pseudechinolaena polystachya (H.B.K.) Stapf., Oplismenus polystachyus Kunth.

Common name(s): [more details]

English: aleman grass, carib grass, creeping rivergrass

Habit:  grass

Description:  "Culms coarse to 2 m high in flower, from a long creeping and rooting base, glabrous, except the nodes hispid with dense yellowish hairs; leaf-blades up to 2.5 cm broad, scabrid; racemes ascending, 3-6 cm long, densely hispid at the base; spikelets nearly sessile, plano-convex, about 5 mm long."  (Adams, 1972)An aquatic or semi-aquatic, perennial, stoloniferous grass.  Leaves flat, smooth, 20-60 cm long and 1-1.5 cm wide  (Csurhes and Edwards, 1998; pp. 156-157).

"Perennial grass with hygro habits, up to 3 m height, with decumbent culms, simple, cylindrical, with long internodes semi-glabrous, roots fasciculated, adventitious rooting may also be observed, leaves of somewhat red-purplish colour, limbs plains, long and acuminated" (Ecoport).

Description from World Grass Species.

Habitat/ecology:  Forms dense stands in seasonal swamps, lake shores and along rivers. Can grow in water up to 2 m deep. (Csurhes & Edwards, 1998; pp. 156-157). "The plant has the potential to form monospecific stands in seasonally wet and dry tropical wetlands, including floodplains, where it could smother native plants" (Smith, 1995, cited in Csurhes & Edwards, 1998; pp. 156-157).

Propagation:  "Spread vegetatively when pieces of stems and roots are distributed by floodwaters.  Seed production in Australia is generally thought to be poor." (Smith, 2002; p. 73).

Native range:  "A native of tropical and subtropical countries of America from southern USA to northern Argentina where it forms dense swards in seasonal swamps and on less wet ground" (Smith, 2002; p. 73).

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Papua New Guinea Papua New Guinea (eastern New Guinea Island)	Papua New Guinea (eastern New Guinea Island)		? (year unknown)

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)	Northern Territory	introduced cultivated	Csurhes, S./Edwards, R. (1998) (pp. 156-157)
Australia Australia (continental)	Northern Territory	introduced invasive cultivated	Smith, Nicholas M. (2002) (p. 73) Established as a weed on the Mary River.
Australia Australia (continental)	Queensland	introduced invasive cultivated	Csurhes, S./Edwards, R. (1998) (pp. 156-157)
Costa Rica Costa Rica	Costa Rica (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2007)
Ecuador (Mainland) Ecuador	Ecuador (Republic of) (continental)	native	U.S. Dept. Agr., Agr. Res. Serv. (2007)
Honduras Honduras	Honduras (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2007)
Mexico Mexico	Mexico (United Mexican States)	native	U.S. Dept. Agr., Agr. Res. Serv. (2007)
Nicaragua Nicaragua	Nicaragua (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2007)
Panama Panama	Panama (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2007)
Perú Perú	Perú (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2007)

Comments:  A serious weed in Queensland, Australia (Smith, 2002; p. 73). Considered a high priority threat to northern Australia (Csurhes and Edwards, 1998; pp. 156-157).

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

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

References:

Adams, C. D. 1972. Flowering plants of Jamaica. University of the West Indies, Mona, Jamaica. 848 pp.

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

Smith, Nicholas M. 2002. Weeds of the wet/dry tropics of Australia - a field guide. Environment Centre NT, Inc. 112 pp.

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