Panicum repens L., Poaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Risk assessment results:  More information needed; score: 9 (Go to the risk assessment)

Common name(s): [more details]

Chinese: pu di shu

English: Victoria grass, couch panicum, creeping panic, quack grass, torpedo grass, wainaku grass

French: millet rampant, panic rampant

Manobo: kayana

Spanish: canota, grama del norte

Tagalog: luya-luyahan

Habit:  grass

Description:  "An erect, rather wiry, creeping, perennial grass, 30-90 cm tall, growing extensively but not densely, rhizomes strongly developed, often swollen or knotty, smooth with brownish or whitish scales, branched, sending out erect culms from the rather distant nodes; culms clothed at base with bladeless sheaths; leaf sheaths fringed with long hairs along the margin, ligule short, fringed with hairs; blades two-ranked, 15 to 25 cm long, 1.5 cm wide or less, acuminate, linear, flat or folded, with a rounded base, smooth or somewhat rough, sparsely long-hairy above, smooth below, covered with a whitish bloom, somewhat rigid, with long white hairs behind ligule, midrib prominent and keeled; panicles exserted, 7 to 18 cm long, somewhat loose and open, erect or ascending, sometimes nodding, elongated, scattered, one to three at each node, branches stiffly ascending, distant, 2 to 19 cm long, smooth or slightly rough; spikelets two-flowered, pale green or pale yellow, often tinged with purple, oblong-ovate, acute or slightly acuminate, 2.2 to 3 mm long; first glume truncate, about one-fifth as long as the spikelet, second glume as long as spikelet, seven- to nine-nerved; first lemma as long as spikelet, five- to nine-nerved; first palea nearly as long as spikelet; anthers yellowish orange; second lemma shorter than spikelet; stigmas purple; caryopsis lanceolate, straw-colored.  The sharp-pointed rhizome which is coarse, swollen, and shaped like a ginger rhizome and the blades which are often covered with whitish waxy bloom are the distinguishing characteristics of this species" (Holm et al., 1977; p. 353).

Description from GrassBase.

Habitat/ecology:  "Primary a weed of moist, coastal, sandy soils, it can also grow on heavy upland soils and can tolerate drought.  It is found most frequently in sandy soils along seacoasts or in poorly drained heavy soils.  It cannot stand permanently flooded conditions, but can withstand occasional flooding and can encroach upon and invade ditches, drains, watercourses, fishponds, and floating mats of vegetation from banks and adjacent areas.  It is frequent in cultivated lands, grasslands, roadsides, and gardens.  It is usually found in low coastal areas and along rivers but it does spread to local inland areas to elevations of 1,500 to 2,000 m in the tropics.  It grows best in open sunny areas but can stand partial shade.  It is very drought-resistant, an the rhizomes may live through prolonged dry periods" (Holm et al., 1977; pp. 353, 356).  Grows up to elevations of 2,000 m in Indonesia.  Favors open sunny conditions, but can stand partial shade.  Rhizomes can stand prolong dry periods  (Waterhouse, 1994; pp. 172-177).  In Hawai‘i, "naturalized in usually moist, disturbed habitats, such as along ditches and roadsides in cane fields, 30-1,100 m"  (Wagner et al., 1999; pp. 1571, 1573); "infests coastal sites and mesic to high-rainfall environments; forms thick, dense stands that smother low plants"  (Motooka et al., 2003).

Propagation:  "The plant spreads mainly by course, extensively creeping rhizomes that may extend as far as 7 m from the parent plant. Seeds are produced in a few situations" (Holm et al., 1977; p. 353).

Native range:  Tropical and north Africa, Mediterranean; now widespread in the tropics.

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Commonwealth of the Northern Mariana Islands (US) Saipan	Saipan Island	native	Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1987) (p. 52)
Commonwealth of the Northern Mariana Islands (US) Saipan	Saipan Island		Bishop Museum (Honolulu) (1984) (voucher ID: BISH 573466) Taxon name on voucher: Panicum repens L.
State of Hawaii Hawaiian Islands	Hawai‘i (Big) Island	introduced invasive	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (pp. 1571, 1573)
State of Hawaii Hawaiian Islands	Lāna‘i Island	introduced invasive	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (pp. 1571, 1573)
State of Hawaii Hawaiian Islands	Maui Island	introduced invasive	Starr, Forest/Martz, Kim/Loope, Lloyd L. (2002) (p. 23) East Maui. Voucher cited: Starr & Martz 980927-1 (BISH)
State of Hawaii Hawaiian Islands	O‘ahu Island	introduced invasive	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (pp. 1571, 1573)
Palau Palau (Belau ) (main island group)	Koror (Oreor) Island	native	Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1987) (p. 52)
Palau Palau (Belau ) (main island group)	Koror (Oreor) Island	introduced invasive	Space, James C./Waterhouse, Barbara/Miles, Joel E./Tiobech, Joseph/Rengulbai, Kashgar (2003) (p. 81)
Palau Palau (Belau ) (main island group)	Koror (Oreor) Island	native	Space, James C./Lorence, David H./LaRosa, Anne Marie (2009) (p. Field notes and voucher.) Voucher: Lorence 9771 (PTBG, BNM, NY, US)
Palau Palau (Belau ) (main island group)	Koror (Oreor) Island		Beleu National Museum (Republic of Palau. Koror.) (1977) (voucher ID: BNM 10007) Taxon name on voucher: Panicum repens L.
Palau Palau (Belau ) (main island group)	Koror (Oreor) Island		National Tropical Botanical Garden (U.S.A. Hawaii. Kalaheo.) (2008) (voucher ID: PTBG 49527) Taxon name on voucher: Panicum repens L.
Palau Palau (Belau ) (main island group)	Palau Islands (main island group)		Bishop Museum (Honolulu) (1977) (voucher ID: BISH 428554) Taxon name on voucher: Panicum repens L.
Philippines Philippine Islands	Philippine Islands	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Philippines Philippine Islands	Philippine Islands	native	Merrill, Elmer D. (1925) (p. 67) In open low lands, especially near the sea, but also inland locally and ascending to 1,500 m; common.

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)	Queensland		Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (p. 355)
Cambodia Cambodia	Cambodia (Kingdom of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
China China	China (People's Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
China China	Hong Kong	native	Wu, Te-lin (2001) (p. 342) In wet places.
Indonesia Indonesia	Indonesia (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Japan Japan	Japan	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Malaysia Malaysia	Malaysia (country of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Mexico Mexico	Mexico (United Mexican States)		Hafliger, Ernst/Scholz, Hildemar (1980) (p. 86)
Negara Brunei Darussalam Brunei	Brunei (Negara Brunei Darussalam)	introduced invasive	Waterhouse, D. F. (1993) (pp. 67, 78)
Singapore Singapore	Singapore (Republic of)	introduced invasive	Waterhouse, D. F. (1993) (pp. 67, 78)
Singapore Singapore	Singapore (Republic of)	native	Chong, Kwek Yan/Tan, Hugh T. W./Corlett, Richard T. (2009) (p. 66) Common
Taiwan Taiwan Island	Taiwan Island	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Thailand Thailand	Thailand (Kingdom of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
United States (west coast) United States (west coast states)	USA (California)	introduced	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2013)
Vietnam Vietnam	Vietnam (Socialist Republic of)	native	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
Australia (Indian Ocean offshore islands) Cocos (Keeling) Islands	Cocos (Keeling) Islands	native	Orchard, Anthony E., ed. (1993) (p. 38)
Seychelles Seychelles Islands	Seychelles Islands	introduced	Weber, Ewald (2003) (p. 298)

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)	introduced	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2013)
United States (continental except west coast) United States (other states)	USA (Florida)	introduced	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2013)

Comments:  Planting of this species is prohibited in Miami-Dade County, Florida (U.S.) (Miami-Dade County Dept. of Planning and Zoning, 2010).

Control: 

Physical: "Difficult because of extensive rhizomes beneath soil surface. Tillage only encourages its growth"  (Motooka et al., 2003).

Chemical:  "Sensitive to glyphosate and imazapyr but will require repeat treatments" (Motooka et al., 2003).

Biological:  Waterhouse (1994, pp. 175-177) lists natural enemies of the species.