Pennisetum clandestinum Hochst. ex Chiov., Poaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Risk assessment results: 

Reject, score: 12 (Go to the risk assessment (Australia))
High risk, score: 18 (Go to the risk assessment (Pacific))

Other Latin names:  Cenchrus clandestinus (Hochst. ex Chiov.) Morrone; Kikuyuochloa clandestina (Hochst. ex Chiov.) H. Scholz

Common name(s): [more details]

Chinese: pu di lang wei cao

English: kikuyo grass, kikuyu grass

French: kikuyu

Spanish: kikuyu, pasto africano

Habit:  grass

Description:  "A low, mat-forming, perennial grass; creeping extensively by stout rhizomes and long branched stolons; culms 30 to 120 cm, prostrate and rooting from the nodes, internodes short, profuse vertical leafy branches arise from the stolons and rhizomes; leaf sheaths overlapping, membranous to papery, pale to brown, hairless or hairy; ligule a hairy rim; blades narrow, spreading, blunt to pointed, 1.25 to 5 cm long, 3 to 4 mm wide, folded at first, later flat, hairless or hairy, the margins rough, the small white or tawny panicles are not borne at the top of the culms as in other grasses but are enclosed within short leaf sheaths at the top of short side shoots which resemble regular vegetative shoots, spikelets in clusters of two to four and nearly enclosed in the uppermost leaf sheath, terminal spikelet shortly stalked, the others stalkless, each spikelet partly or wholly surrounded by delicate bristles up to 15 in number that are unequal in length, inner bristles plumose, spikelets with two florets, slender, narrow, 1 to 2 cm long, whitish below, greenish above; the only parts of the flower visible are the stamens which appear as a mass of fine white threads attached to the leaves and consist of filaments, 2.5 cm or more long, with anthers at the tip; grain (caryopsis) oblong, brown, 1.5 to 2.5 mm long, the seeds can be found only by dissecting the leaf sheaths.  The species can be distinguished by its extensively creeping rhizomes and stolons which form a dense mat, its culms with overlapping leaf sheaths and by its flowers which, if present at all, appear on leafy, vegetative side shoots with only the stamens visible above the leaf sheaths"  (Holm et al., 1977; p. 362).

Description from GrassBase.

Habitat/ecology:  "A creeping, sod-forming grass that can spread rapidly to form vigorous pure stands.  It is well adapted to the humid tropic or subtropics, especially at higher elevations and in soils of high fertility.  It has long been associated with volcanic soils or with the red soils of the tropics and subtropics.  Although the grass grows best under moist, humid conditions, well-establlished plants can withstand a considerable amount of dry weather; however, they do not grow as rapidly during such periods of moisture stress" (Holm et al., 1977; pp. 362, 364).  "This rapidly growing, partially scrambling, rhizomatous plant is a favored, but overrated, rangeland grass. It is a serious pest in forests because, apart from shading out shrubs and herbs, it releases allelopathic substances which kill almost all other species in the vicinity (Sanchez and Davis 1969). It burns very slowly and generally retards fire.  "This strongly creeping grass can form swards over several hectares in area and is difficult to eradicate. Because shading does not stop its growth, it can grow up through hedges and bushes, eventually shading them to extinction. Where kikuyu grass grows in open scrubland or on forest margins the seedlings of native trees and shrubs have very little chance of establishment. Kikuyu grass creates a considerable fire hazard as the old stolons die and accumulate because of the new growth scrambling over the top" (Edgar & Connor, 2000; p. 574)

It is found on all major Hawaiian Islands from 500-2,000 m in dry and mesic habitats. It will also invade wet environments when the forest is disturbed" (Smith, 1985). In Hawai‘i, "naturalized in dry to mesic forest, open sites in wet forest, and pastures, 0-1,220 m.  Kikuyu grass is one of the most serious pest species threatening native vegetation; its smothering, thick, dense growth prevents virtually any new seedling establishment"  (Wagner et al., 1999; pp. 1578-1579). In New Caledonia, "cultivé à présent en pâturages et gazons mais peu commun" (MacKee, 1994; p. 61).

Propagation:  Rhizomes and stolons; wind-dispersed seeds (rarely). "It produces strong vigorous stolons and rhizomes which spread rapidly in a circular pattern from the parent plant, colonizing bare ground or encroaching on croplands, grasslands, forest, and waste areas.  Stolons root readily at the nodes.  The thick, white rhizomes spread through the soil to a depth of 30 to 40 cm or more, producing a tough, dense sod difficult to plow or to penetrate with tillage equipment.  Both rhizomes and tillers can survive considerable drying after tillage; however, severe desiccation will kill them.  The plant can withstand severe and repeated defoliation; hence, it is very resistant to overgrazing or mowing" (Holm et al., 1977; p. 364).

Native range:  Tropical eastern Africa (Holm et al., 1977; p. 362).

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Australia (Pacific offshore islands) Lord Howe Island	Lord Howe Island	introduced	Pickard, J. (1984) (p. 205)
Australia (Pacific offshore islands) Lord Howe Island	Lord Howe Island	introduced invasive	Orchard, Anthony E., ed. (1994) (p. 22) "Introduced and is commonly used as a pasture grass, and also in lawns". Vouchers cited: L.M. Bingley 30 (K, NSW), A.C. Beauglehole 5457 (CANB, MEL), A.C. Beauglehole 5979 (CANB)
Australia (Pacific offshore islands) Norfolk Islands	Norfolk Island	introduced invasive	Ziesing, P. (1997) (pp. 32-33)
Australia (Pacific offshore islands) Norfolk Islands	Norfolk Island	introduced invasive	Orchard, Anthony E., ed. (1994) (p. 12) "Introduced and is commonly used as a pasture grass, and also in lawns". Vouchers cited: W.R. Sykes NI 55 (CHR), P. Ralston 5 (CHR)
Chile (offshore islands) Rapa Nui (Easter) Island	Rapa Nui (Easter) Island (Isla de Pasqua)	introduced invasive	Meyer, Jean-Yves (2008) (p. 29)
French Polynesia Marquesas Islands	Nuku Hiva (Nukahiva) Island		National Tropical Botanical Garden (U.S.A. Hawaii. Kalaheo.) (2004) (voucher ID: PTBG 42445) Taxon name on voucher: Pennisetum clandestinum
French Polynesia Society Islands	Tahiti Island	introduced invasive	Florence, J./Chevillotte, H./Ollier, C./Meyer, J.-Y. (2013) Adventice
State of Hawaii Hawaiian Islands	Hawai‘i (Big) Island	introduced invasive cultivated	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (pp. 1578-1580) Voucher cited: Hosaka 2181 (BISH)
State of Hawaii Hawaiian Islands	Kaua‘i Island	introduced invasive	Wagner, Warren L./Herbst, Derral R. (1995) (p. 24) Vouchers cited: Plews s.n. (BISH), Flynn et al. 2712 (BISH, PTBG)
State of Hawaii Hawaiian Islands	Lāna‘i Island	introduced invasive cultivated	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (pp. 1578-1580)
State of Hawaii Hawaiian Islands	Maui Island	introduced invasive cultivated	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (pp. 1578-1580)
State of Hawaii Hawaiian Islands	Moloka‘i Island	introduced invasive cultivated	Hughes, Guy D'Oyly (1995) (p. 9) Voucher cited: Hughes 335 (US) Naturalized to 1100 m elevation, out-competing many native species for space and light.
State of Hawaii Hawaiian Islands	O‘ahu Island	introduced invasive cultivated	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (pp. 1578-1580)
New Caledonia New Caledonia Archipelago	Île Grande Terre	introduced cultivated	MacKee, H. S. (1994) (p. 61) Voucher cited: MacKee 43835
New Guinea (Indonesia and Papua New Guinea) New Guinea Island	New Guinea Island		Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. (1979) (p. 271)
Papua New Guinea Papua New Guinea (eastern New Guinea Island)	Papua New Guinea (eastern New Guinea Island)	introduced cultivated	Henty, E. E. (1969) (p. 147)
Wallis and Futuna Wallis and Futuna (Horne) Islands	Wallis (‘Uvea) Island	introduced cultivated	Meyer, Jean-Yves (2007) (p. 13)
Wallis and Futuna Wallis and Futuna (Horne) Islands	Wallis (‘Uvea) Island	introduced invasive cultivated	Meyer, Jean-Yves/Jourdan, Hervé/Malau, Atoloto (2008) (p. 9)

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	introduced invasive	Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (p. 364)
Cambodia Cambodia	Cambodia (Kingdom of)		Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. (1979) (p. 271)
Central America Central America (Pacific rim)	Costa Rica (Republic of)	introduced invasive	Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (p. 366)
Central America Central America (Pacific rim)	Guatemala (Republic of)		Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. (1979) (p. 271)
Central America Central America (Pacific rim)	Panama (Republic of)		Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. (1979) (p. 271)
China China	China (People's Republic of)		Hafliger, Ernst/Scholz, Hildemar (1980) (p. 112)
Indonesia Indonesia	Indonesia (Republic of)		Hafliger, Ernst/Scholz, Hildemar (1980) (p. 112)
Mexico Mexico	Mexico (United Mexican States)	introduced	Weber, Ewald (2003) (p. 310)
New Zealand New Zealand	New Zealand (country)	introduced invasive	Owen, S. J. (1997)
New Zealand New Zealand	New Zealand (country)	introduced invasive	Edgar, E./Connor, H. (2000) (p. 574) "Pastures, coastal (sandy or rocky foreshore), reclamation areas, roadsides, lawns, stream banks".
South America (Pacific rim) South America (Pacific rim)	Colombia	introduced invasive	Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (p. 365)
South America (Pacific rim) South America (Pacific rim)	Ecuador (Republic of) (continental)	introduced invasive	Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (p. 365)
South America (Pacific rim) South America (Pacific rim)	Perú (Republic of)	introduced invasive	Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (p. 365)
Taiwan Taiwan Island	Taiwan Island	introduced invasive	Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (p. 366)
United States (west coast) United States (west coast states)	USA (California)	introduced invasive	Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (p. 366)
United States (west coast) United States (west coast states)	USA (California)	introduced invasive	Motooka, Philip/Castro, Luisa/Nelson, Duane/Nagai, Guy/Ching, Lincoln (2003) "A serious weed in California".

Indian Ocean
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
La Réunion (France) La Réunion Island	La Réunion Island	introduced invasive	Lavergne, Christophe (2006) "Envahissant"
Mauritius Mautitius Islands (Mauritius and Rodrigues)	Mauritius Island		Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. (1979) (p. 271)

Comments:  In the past, often used for soil stabilization. Not recommended due to its invasive nature. On U.S. Federal noxious weed list. A problem in Hawai‘i, La Réunion, Australia, New Zealand and South Africa.

Control: 

Physical: Difficult to dig out as all rhizomes must be removed.

Chemical: Roundup (without Pulse) 1%, Dowpon 740-SP (16-20 g/l sater), Gallant (0.5%); spray new growth, spot spray regrowth (Timmins and Mackenzie, 1995; pp. 195-197).  "Sensitive to glyphosate and imazapyr. HAVO staff reported control with glyphosate at 1% of product in water applied to wet the green foliage (Chris Zimmer, HAVO)"  (Motooka et al., 2003).  "The grass can be eradicated by spraying with 0.5% glyphosate (Gardner and Kageler, 1983) or Dalapon (Hosaka, 1958)" (Smith, 1985; pp. 197-198).

Biological: It has been evaluated for biological control in Hawai‘i but no action will be taken because of its agricultural importance (Gardner and Davis, 1982). A rust (Phakospora aroda (Har. and Pat.) Mains) has recently become established on in Hawai‘i but its impact is not yet known (Gardner, 1984). Two insect pests, Sphenophorus ventus vestitus and Herpetogramma licarsicalis, damage kikuyu grass in Hawai‘i (Cronk & Fuller, 2001; p. 179).  "Susceptible to the yellow sugarcane aphid (Sipha sp.)" (Motooka et al., 2003).