Pennisetum macrourum Trin., Poaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Risk assessment results:  Reject, score: 26 (Go to the risk assessment)

Common name(s): [more details]

English: African feathergrass, bedding grass, waterside reed

Habit:  grass

Description:  "Reed-like perennial from a creeping rhizome; culms 0.6-5 m high, often robust, scaberulous or occasionally pubescent below the panicle; nodes brown. Leaf-blades 10-45 cm long, 2-10 (-15) mm wide, hard, glaucous, often convolute, with a filiform tip. Panicle linear, often elongated, 6-40 cm long; rhachis cylindrical with rounded ribs, with or without peduncle-stumps, scaberulous or sometimes pubescent; involucre enclosing 1 sessile spikelet, without a distinct stipe at the base; bristles glabrous, the longest 5-20 mm. Spikelets narrowly elliptic to narrowly ovate, 2-6 mm long, acute or acuminate; lower glume up to 1 mm long, usually obtuse; upper glume 1/8-1/4 as long as the spikelet, usually acute to acuminate, occasionally obtuse; lower lemma male or barren, 3/4 to as long as the spikelet; upper lemma scarcely differing in texture from the lower" (Clayton & Renvoize, 1982; p. 689).

Description from GrassBase.

Habitat/ecology:  "Grassland, riparian habitats, freshwater wetlands. The strong rhizome growth increases rapidly the size of individual clumps and lead to a dense mat that eliminates all other vegetation. Once established, the grass is relatively drought resistant, persistent and individual clones expand by vegetative growth" (Weber, 2003; p. 311). "The plant prefers subhumid warm-temperature regions (usually where annual rainfall exceeds 600 mm) and normally occurs on streambanks, roadsides and pastures, often in sandy soil (Parsons & Cuthbertson, 1992, cited in Csurhes & Edwards, 1998).

In New Zealand, "Forms dense clumps that exclude other vegetation. Pastures, roadsides, wasteland and urban areas. Likes damp situations such as swamps and along the borders of streams, but can tolerate drought and establish on dry shady banks; prefers light sandy soil." (Fact sheet on Pennisetum macrourum from the Environment Bay of Plenty Regional Council [New Zealand])) In Australia, "infestations...were first confined to moist areas near rivers, lagoons and other low lying areas subject to flooding.  It has gradually spread beyond such places to drier, improved or unimproved areas" (Lamp et al., 1990, cited in Csurhes & Edwards, 1998; p. 185).

Propagation:  "Reproduction occurs from animal and water-dispersed seed and rhizomes" (Swarbrick & Skarratt, 1994, cited in Csurhes & Edwards, 1998; p. 185).

"Root and rhizome fragments can easily regenerate new plants.  Seeds are dispersed by water and by adhering to animals"  (Weber, 2003; p. 311).

Native range:  Africa, Yemen (GRIN).

Impacts and invaded habitats:  "The strong rhizome growth increases rapidly the size of individual clumps and lead to a dense mat that eliminates all other vegetation." (Weber, 2003; p. 311)

In New Zealand, "Forms dense clumps that exclude other vegetation." (Fact sheet on Pennisetum macrourum from the Environment Bay of Plenty Regional Council [New Zealand])).

In New Zealand, "Forms dense clumps, crowding out and suppressing low growing plants in pasture and antive ecosystems, unpalatable to stock, blocks drains." (Friendly Alternatives, p 4)

In Australia, "infestations...were first confined to moist areas near rivers, lagoons and other low lying areas subject to flooding.  It has gradually spread beyond such places to drier, improved or unimproved areas" (Lamp et al., 1990, cited in Csurhes & Edwards, 1998; p. 185).

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		U.S. Dept. Agr., Nat. Res. Cons. Serv. (2013)

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)	Australia (continental)	introduced invasive	Csurhes, S./Edwards, R. (1998) (p. 185) Victoria and South Australia
New Zealand New Zealand	New Zealand (country)	introduced invasive	Edgar, E./Connor, H. (2000) (p. 576) "Roadsides, grassy areas, lowland and hill country pasture, creek edges, swampy soil, sandy soil".

Comments:  On US noxious weed list and several state lists. "Naturalized in Australia and New Zealand" (GRIN).

Control:  For additional control information see the information sheet from Weedbusters New Zealand.

Physical: Dig out small infestations.

Chemical: "Gallant® NF Knapsack: 150 ml per 10 litres water

Handgun: 500 ml per 100 litres water Crop oil must be added at 50 ml per 10 litres of spray mix. When applying the herbicide it is important that good coverage is achieved. Repeat applications may still be necessary toeffectively kill larger plants." (Fact sheet on Pennisetum macrourum from the Environment Bay of Plenty Regional Council [New Zealand]))