Pacific Island Ecosystems at Risk (PIER)

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Echinochloa polystachya
(Kunth) Hitchc., Poaceae
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Present on Pacific Islands?  no

Primarily a threat at high elevations?  no

Risk assessment results: 

Australia:  Reject, score: 13 (Go to the risk assessment)
Risk assessment of Echinochloa polystachya from the Government of Queensland, Australia (PDF format).

Other Latin names:  Echinochloa spectabilis (Nees ex Trin.) Link; Oplismenus polystachyus Kunth.; Panicum polystachyum (Kunth) Steud.; Panicum spectabile Nees ex Trin.

Common name(s): [more details]

English: aleman grass, creeping rivergrass

Spanish: paja pelua, pasto chiguirera

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 grassLeaves 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 GrassBase.

Habitat/ecology:  "Freshwater wetlands, riparian habitats.  A C4 aquatic grass of floodplains and estuaries with a very high productivity.  The grass does not tolerate drought and frosts, and grows well in standing water.  It is adapted to wet and very wet soils, and to varying water levels.  The fast growing grass forms extensive monotypic stands on the lower levels of floodplains, crowding out native water plants and altering the vegetation structure.  It grows rapidly during floods and decays rapidly during water retreat, resulting in a high release of nutrients during the low water period.  This nutrient flush may affect water quality and reduce the oxygen content"  (Weber, 2003; p. 143).

"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).

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 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)
Chile (continental)
Chile
Chile (Republic of) native
U.S. Dept. Agr., Agr. Res. Serv. (2013)
Costa Rica
Costa Rica
Costa Rica (Republic of) native
U.S. Dept. Agr., Agr. Res. Serv. (2013)
Ecuador (Mainland)
Ecuador
Ecuador (Republic of) (continental) native
U.S. Dept. Agr., Agr. Res. Serv. (2013)
Honduras
Honduras
Honduras (Republic of) native
U.S. Dept. Agr., Agr. Res. Serv. (2013)
Mexico
Mexico
Mexico (United Mexican States) native
U.S. Dept. Agr., Agr. Res. Serv. (2013)
Nicaragua
Nicaragua
Nicaragua (Republic of) native
U.S. Dept. Agr., Agr. Res. Serv. (2013)
Panama
Panama
Panama (Republic of) native
U.S. Dept. Agr., Agr. Res. Serv. (2013)
Perú
Perú
Perú (Republic of) native
U.S. Dept. Agr., Agr. Res. Serv. (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., Agr. Res. Serv. (2013)
Louisiana, Texas
United States (continental except west coast)
United States (other states)
USA (Florida) native
U.S. Dept. Agr., Agr. Res. Serv. (2013)

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).

Control:  "Scattered plants may be removed manually, larger stands treated with herbicide"  (Weber, 2003; p. 143).


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This page was created on 1 JAN 1999 and was last updated on 7 MAY 2017.