Imperata conferta (J.Presl) Ohwi, Poaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Other Latin names:  Imperata exaltata auct.; Saccharum confertum J. Presl

Common name(s): [more details]

English: plume grass

Fijian: gi, ngi

Habit:  grass

Description: 

Genus:  "Rhizome subterranean; flowering culms of few internodes, tall; leaf-blades nearly all arising from near the base of the culm, very long, erect; inflorescence a much branched panicle, its branches ascending close to the main axis, the whole compact and cylindric at flowering; branchlets not jointed, spikelets paired or solitary, all alike, bisexual, if paired pedicels unequal, and bearing a few long fine hairs near the thickened top and many fine spreading white hairs also on the base of the spikelets, hairs twice as long as the glumes or more; glumes about equal, hairy on the back, thin; lower floret neuter, lemma much smaller than the glumes, no palea; upper floret hermaphrodite, lemma thin, not awned, palea present."

Key to species of Imperata:

Imperata cylindrica:  Stamens 2.  Panicle up to 30 x 2 cm.
Imperata conferta:  Stamen 1.  Panicle up to 50 x 5 cm.

Species:  "As in [Imperata cylindrica], similarly rhizomatous and spreading, nodes glabrous or short-hairy, a larger plant but with smaller flowers.  Leaf-sheaths loose, 12.5 cm or longer; blades narrowing to each end, acuminate, less scabrid on the margins, up to 45.0 x 1.4 cm; ligule membranous, nearly glabrous.  Inflorescence a strict but more open panicle, up to 50 cm long by 5 cm across, the lowest branches to 12 cm long, ultimately capillary, with the spikelets mainly in pairs, one long pedicelled, 2.6 mm and one short pedicelled, 1.2 mm; spikelets all alike, callus furnished with long silky hairs 2.2 cm long, lower glume 3 mm long, delicate 3-nerved, lanceolate-acuminate; upper glume likewise, 2.8 mm long; lower lemma 1-nerved, narrowly linear-acuminate; upper glume likewise, 2.8 mm long; lower lemma 1-nerved, narrowly linear-acuminate, delicately hyaline, 2 mm long; palea nil; upper lemma delicately hyaline, 1-nerved and denticulate, 2 mm long; palea delicately hyaline, wrapped around the stamen and pistil, 1.2 mm long; stamen 1, anthers 2 mm long; stigmata plumose, purplish" (Gilliland, 1971; pp. 220-221).

Description from GrassBase.

Habitat/ecology:  In Fiji, "common from sea level to about 900 m, occurring on hillsides, along streams and trails in dense or open forest, on damp slopes, along roadsides, and on coconut plantations" (Smith, 1979; pp. 365-366).  "Common in Samoa on high-elevation lava flows, elsewhere uncommon in sunny, disturbed places" (Whistler, 1988; p. 53). In New Guinea, "from sea level to 3000 m" (Henty & Pritchard, 1975; p. 42).

Propagation:  Seed

Native range:  Southeastern Asia and Malesia (Smith, 1979; pp. 365-366).

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
American Samoa Manu‘a Islands	Ta‘u Island		National Tropical Botanical Garden (U.S.A. Hawaii. Kalaheo.) (1991) (voucher ID: PTBG 9504) Taxon name on voucher: Imperata conferta
Commonwealth of the Northern Mariana Islands (US) Northern Mariana Islands	Rota Island	introduced	Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1987) (p. 44)
Commonwealth of the Northern Mariana Islands (US) Northern Mariana Islands	Tinian Island	introduced	Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1987) (p. 44)
Commonwealth of the Northern Mariana Islands (US) Northern Mariana Islands	Tinian Island	introduced	Fosberg, F. R./Sachet, M.-H. (1982) (pp. 49-50) Vouchers cited: Fosberg 59882 (US, BISH), Herbst & Falanruw 6807 (US)
Commonwealth of the Northern Mariana Islands (US) Saipan	Saipan Island	introduced	Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1987) (p. 44)
Commonwealth of the Northern Mariana Islands (US) Saipan	Saipan Island	introduced	Fosberg, F. R./Sachet, M.-H. (1982) (pp. 49-50) Voucher cited: Herbst & Falanruw 6894 (US)
Federated States of Micronesia Yap Islands	Yap (Waqab) Island	introduced	Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1987) (p. 44)
Federated States of Micronesia Yap Islands	Yap (Waqab) Island	possibly native	Fosberg, F. R./Sachet, M.-H. (1982) (pp. 49-50) Vouchers cited: Takamatsu 1925 (US, POM, BISH), Takematsu 1901 (US, POM, BISH), Cushing 378 (US)
Fiji Fiji Islands	Kandavu Island	introduced invasive	Smith, Albert C. (1979) (pp. 365-366) Voucher cited: DA 9080
Fiji Fiji Islands	Koro Island	introduced invasive	Smith, Albert C. (1979) (pp. 365-366)
Fiji Fiji Islands	Lakemba Island	introduced invasive	Smith, Albert C. (1979) (pp. 365-366)
Fiji Fiji Islands	Matuku Island	introduced invasive	Smith, Albert C. (1979) (pp. 365-366)
Fiji Fiji Islands	Moala Island	introduced invasive	Smith, Albert C. (1979) (pp. 365-366)
Fiji Fiji Islands	Moturiki Island	introduced invasive	Smith, Albert C. (1979) (pp. 365-366)
Fiji Fiji Islands	Ngau Island	introduced invasive	Smith, Albert C. (1979) (pp. 365-366)
Fiji Fiji Islands	Ovalau Island	introduced invasive	Smith, Albert C. (1979) (pp. 365-366)
Fiji Fiji Islands	Taveuni Island	introduced invasive	Smith, Albert C. (1979) (pp. 365-366) Vouchers cited: Gillespie 4714, DA 8911
Fiji Fiji Islands	Vanua Levu Island	introduced invasive	Smith, Albert C. (1979) (pp. 365-366) Vouchers cited: DA 8762, DA 8787, DA 8868, Degener & Ordonez 14204, DA 16875
Fiji Fiji Islands	Viti Levu Island	introduced invasive	Smith, Albert C. (1979) (pp. 365-366) Vouchers cited: DA 11335, Degener & Ordonez 13572, DA 2093, DA 9030, Smith 9485, DA 8624, Smith 8769, DA 7308, Gillespie 3163.5, DA 3981, DA 1206, DA 9328, C.R. Turbet 33
Fiji Fiji Islands	Wakaya Island	introduced invasive	Smith, Albert C. (1979) (pp. 365-366)
Guam Guam Island	Guam Island	introduced	Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1987) (p. 44)
Guam Guam Island	Guam Island	introduced	Fosberg, F. R./Sachet, M.-H. (1982) (pp. 49-50) Vouchers cited: Fosberg 59648 (US, BISH, POM, MO, K, BRI), P. H. Moore 889 (US, GUAM), Falanruw 956 (US), Stone 4717 (GUAM)
New Caledonia New Caledonia	New Caledonia Islands		Swarbrick, John T. (1997) (p. 93)
New Guinea (Indonesia and Papua New Guinea) New Guinea Island	New Guinea Island	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Palau Palau (Belau ) (main island group)	Angaur (Ngeaur) Island	introduced	Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1987) (p. 44)
Palau Palau (Belau ) (main island group)	Angaur (Ngeaur) Island	introduced invasive	Space, James C./Waterhouse, Barbara/Miles, Joel E./Tiobech, Joseph/Rengulbai, Kashgar (2003) (p. 103)
Palau Palau (Belau ) (main island group)	Angaur (Ngeaur) Island	possibly native	Fosberg, F. R./Sachet, M.-H. (1982) (pp. 49-50) Voucher cited: Canfield 190 (US)
Palau Palau (Belau ) (main island group)	Babeldaob Island	introduced	Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1987) (p. 44)
Palau Palau (Belau ) (main island group)	Babeldaob Island	introduced invasive	Space, James C./Waterhouse, Barbara/Miles, Joel E./Tiobech, Joseph/Rengulbai, Kashgar (2003) (p. 101)
Palau Palau (Belau ) (main island group)	Babeldaob Island	possibly native	Fosberg, F. R./Sachet, M.-H. (1982) (pp. 49-50) Vouchers cited: Tuyama i 1937 (TI, in part), Kanehira & Hatusima 4551 (FU), Hosaka 3386 (BISH, US, K), Timberlake 3144 (US)
Palau Palau (Belau ) (main island group)	Babeldaob Island	introduced invasive	Space, James C./Lorence, David H./LaRosa, Anne Marie (2009) (p. 60) Voucher: Lorence 9810 (PTBG)
Palau Palau (Belau ) (main island group)	Babeldaob Island		Beleu National Museum (Republic of Palau. Koror.) (1981) (voucher ID: BNM 3144) Taxon name on voucher: Imperata conferta (Presl.) Ohwi
Palau Palau (Belau ) (main island group)	Babeldaob Island		National Tropical Botanical Garden (U.S.A. Hawaii. Kalaheo.) (2008) (voucher ID: PTBG 49591) Taxon name on voucher: Imperata conferta (Presl) Ohwi
Palau Palau (Belau ) (main island group)	Koror (Oreor) Island	introduced	Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1987) (p. 44)
Palau Palau (Belau ) (main island group)	Koror (Oreor) Island	possibly native	Fosberg, F. R./Sachet, M.-H. (1982) (pp. 49-50) Voucher cited: Fosberg 37079 (US, BISH)
Palau Palau (Belau ) (main island group)	Peleliu (Beliliou) Island	introduced invasive	Space, James C./Waterhouse, Barbara/Miles, Joel E./Tiobech, Joseph/Rengulbai, Kashgar (2003) (p. 106)
Palau Rock Islands (Chelbacheb)	Aulupse‘el (Ulebsechel) Island	introduced	Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1987) (p. 44)
Palau Rock Islands (Chelbacheb)	Aulupse‘el (Ulebsechel) Island	possibly native	Fosberg, F. R./Sachet, M.-H. (1982) (pp. 49-50) Voucher cited: Fosberg 32362 (US)
Papua New Guinea Papua New Guinea (eastern New Guinea Island)	Papua New Guinea (eastern New Guinea Island)	invasive	Henty, E. E. (1969) (p. 111) Commmon in grassland, becoming dominant on deeper, more fertile or recently disturbed soil.
Papua New Guinea Papua New Guinea (eastern New Guinea Island)	Papua New Guinea (eastern New Guinea Island)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Philippines Philippine Islands	Philippine Islands	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Philippines Philippine Islands	Philippine Islands		Merrill, Elmer D. (1925) (p. 31) As Imperata exaltata Brongn.
Samoa Western Samoa Islands	Upolu Island		National Tropical Botanical Garden (U.S.A. Hawaii. Kalaheo.) (1989) (voucher ID: PTBG 4070) Taxon name on voucher: Imperata conferta
Samoa Western Samoa Islands	Western Samoa Islands		Whistler, W. A. (1988) (p. 53)
Solomon Islands Solomon Islands	Solomon Islands		Swarbrick, John T. (1997) (p. 93)
Tonga Ha‘apai Group	Kao Island	possibly introduced	Whistler, W. A. (1992) (p. 99) Vouchers cited: Yuncker 15918, Yuncker 15936
Tonga Ha‘apai Group	Kao Island		Yuncker, T. G. (1959) (p. 64) As Imperata cylindrica; vouchers cited: Yuncker 15918, Yuncker 15936
Tonga Ha‘apai Group	Tofua Island	possibly introduced	Whistler, W. A. (1992) (p. 99) Vouchers cited: Hotta 4426, Scarth-Johnson 110
Tonga Tongatapu Group	‘Eua Island	possibly introduced	Whistler, W. A. (1992) (p. 99) Vouchers cited: Parks 16239, Yuncker 15457, Sykes 332a, Sykes 669, Whistler 7407
Tonga Tongatapu Group	‘Eua Island		Yuncker, T. G. (1959) (p. 64) As Imperata cylindrica; voucher cited: Yuncker 15457
Tonga Vava‘u Group	Late Island	introduced	Sykes, W. R. (1981) (p. 352)
Tonga Vava‘u Group	Late Island	possibly introduced	Whistler, W. A. (1992) (p. 99) Vouchers cited: Hotta 4450! (cf. 4456), Hotta 4459!, Buelow & Sykes 93
Tonga Vava‘u Group	Tafahi Island	possibly introduced	Whistler, W. A. (1992) (p. 99) Voucher cited: Whistler 6289
Vanuatu New Hebrides Islands	Vanuatu (Republic of)		Swarbrick, John T. (1997) (p. 93)
Wallis and Futuna Wallis and Futuna (Horne) Islands	Wallis and Futuna Islands		Whistler, W. A. (1988) (p. 53)

Pacific Rim
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Indonesia Indonesia	Indonesia (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013) Java
Malaysia Malaysia	Malaysia (country of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Singapore Singapore	Singapore (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Singapore Singapore	Singapore (Republic of)	native	Chong, Kwek Yan/Tan, Hugh T. W./Corlett, Richard T. (2009) (p. 50) Common
Thailand Thailand	Thailand (Kingdom of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)

Control:  If you know of control methods for Imperata conferta, please let us know.