Sporobolus pyramidatus (Lam.) Hitchc., Poaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Risk assessment results:  High risk, score: 14 (Go to the risk assessment).

Common name(s): [more details]

English: giant rat's tail grass, whorled dropseed

Habit:  grass

Description:  "Low, tufted perennial.  Culms numerous, often spreading at base, glabrous, mostly 10-50 cm tall.  Sheaths glabrous or with a few hairs on the upper margins.  Ligule a fringe of hairs on a membranous collar, 0.5-0.8 mm long.  Blades flat, 3-12 (-20) cm long and mostly 2-4 mm broad, usually ciliate on lower margins and sparsely hispid on adaxial surface.  Panicles open, more or less pyramidal, mostly 3-15 (-18) cm long and 2-5 cm broad at base, the lower and middle branches in whorls and bare of spikelets on the lower 1/3-1/2.  Spikelets 1.5-2.0 mm long, the lateral ones on very short pedicels.  Glumes very unequal, thin, acute, the first 0.3-0.8 mm long, the second as long as the lemma.  Lemma acute, glabrous or scabrous.  Palea hyaline, slightly shorter than the lemma.  Grain broadly oblong, flattened laterally, usually 0.6-0.9 mm long, pale orange, the pericarp finely striate" (Howard, 1979; pp. 73-74).

Description from GrassBase.

Habitat/ecology:  "Frequent on coastal sands and inland on low, saline or alkaline sites" (Howard, 1979; pp. 73-74).  In Hawai‘i, "adventive in coastal sites" (Wagner et al., 1999; p. 1596). "In open sandy or alkaline soil" (Wiggins & Porter, 1971; pp. 880-881).

Propagation:  "Mature seeds become sticky when damp and are dispersed when adhered to animal fur, clothes, vehicles and machinery.  Roadside slashing equipment seems to be responsible for much spread along roadsides in rural areas.  Also dispersed by water and as a contaminant of nay.  The thousands of seeds produced have a viability of up to 10 years.  Seeds rapidly, even if grazed or slashed."  (Smith, 2002; p. 77).

Native range:  "Kansas to Colorado [U.S.] and south through the West Indies and Mexico to Argentina" (Howard, 1979; pp. 73-74).

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	French Frigate Shoals	introduced invasive	Wagner, Warren L./Herbst, Derral R. (1995) (pp. 24-25) Voucher cited: Herbst 6232 (BISH)
State of Hawaii Hawaiian Islands	Hawai‘i (Big) Island	introduced invasive	Snow, Neil/Lau, Alex (2010) (p. 56) Voucher cited: C. Imada et al. 94-3 (BISH)
State of Hawaii Hawaiian Islands	Kaho‘olawe Island	introduced invasive	Starr, Forest/Starr, Kim (2011) (p. 31) Voucher cited: Starr, Starr & Hagashino 080210-01 (BISH)
State of Hawaii Hawaiian Islands	Kaua‘i Island	introduced invasive	Wood, K. R. (2006) (p. 18) Vouchers cited: K.R. Wood 10709 (BISH, PTBG, NY, US), K.R. Wood 10914 (PTBG)
State of Hawaii Hawaiian Islands	Kure Atoll	introduced invasive	Wagner, Warren L./Herbst, Derral R. (1995) (pp. 24-25) Voucher cited: Herbst 6271 (BISH)
State of Hawaii Hawaiian Islands	Kure Atoll	introduced invasive	Starr, Forest/Martz, Kim/Loope, Lloyd (2001) (p. 17) Common on runway margins and in open areas.
State of Hawaii Hawaiian Islands	Laysan Island	introduced invasive	Wagner, Warren L./Herbst, Derral R. (1995) (pp. 24-25) Voucher cited: McDermond & Niethammer s.n. (BISH)
State of Hawaii Hawaiian Islands	Laysan Island	introduced invasive	Starr, Forest/Martz, Kim (1999) (p. 11) Patches of this grass were seen on the south side of the lake on and near the guano hard pan.
State of Hawaii Hawaiian Islands	Moloka‘i Island	introduced invasive	Starr, Forest/Starr, Kim/Loope, Lloyd L. (2006) (p. 40) Voucher cited: Starr & Starr 050517-6 (BISH)
State of Hawaii Hawaiian Islands	O‘ahu Island	introduced invasive	Wagner, Warren L./Herbst, Derral R. (1995) (pp. 24-25) Vouchers cited: Whitney 4040 (BISH), Stone 1243 (BISH), Herbst 1367 (BISH), Herbst & Walker 6086 (BISH), Herbst & Walker 6073 (BISH), Herbst 6159 (BISH)
State of Hawaii Hawaiian Islands	Tern Island	introduced invasive	Starr, Forest/Martz, Kim (1999) (p. 7) Dense near the edge of the runway and common further in vegetation.
Solomon Islands Solomon Islands	Solomon Islands		Swarbrick, John T. (1997) (p. 97)
Solomon Islands Solomon Islands	Solomon Islands	native	Hancock, I. R./Henderson, C. P. (1988) (p. 110)
United States (other Pacific offshore islands) Midway Atoll	Eastern Island	introduced invasive	Starr, Forest/Starr, Kim/Loope, Lloyd (2008) (pp. B-13) Voucher cited: Starr & Starr 080605-02
United States (other Pacific offshore islands) Midway Atoll	Sand Island	introduced invasive	Starr, Forest/Starr, Kim/Loope, Lloyd (2008) (pp. B-13) Voucher cited: Starr & Starr 080602-01
United States (other Pacific offshore islands) Midway Atoll	Spit Island	introduced invasive	Starr, Forest/Starr, Kim/Loope, Lloyd (2008) (pp. B-13) Voucher cited: Starr & Starr 080603-01
United States (other Pacific offshore islands) Midway Atoll	Spit Island	introduced invasive	Starr, Forest/Starr, Kim/Loope, Lloyd L. (2010) (p. 66) Voucher cited: Starr & Starr 080603-01 (BISH)

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	Smith, Nicholas M. (2002) (p. 77)
Central America Central America (Pacific rim)	Costa Rica (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Central America Central America (Pacific rim)	El Salvador (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Central America Central America (Pacific rim)	Guatemala (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Central America Central America (Pacific rim)	Honduras (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Central America Central America (Pacific rim)	Nicaragua (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Central America Central America (Pacific rim)	Panama (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)
Singapore Singapore	Singapore (Republic of)	introduced invasive	Chong, Kwek Yan/Tan, Hugh T. W./Corlett, Richard T. (2009) (p. 81) Sporobolus indicus (L.) R. Br. var. pyramidalis (P. Beauv.) Veldk., casual
South America (Pacific rim) South America (Pacific rim)	Chile (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
South America (Pacific rim) South America (Pacific rim)	Colombia	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
South America (Pacific rim) South America (Pacific rim)	Ecuador (Republic of) (continental)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
South America (Pacific rim) South America (Pacific rim)	Perú (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
British Indian Ocean Territory Chagos Archipelago	Diego Garcia Island	introduced invasive	Rivers, Julie (2004) (p. 2)

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)

Control:  If you know of control methods for Sporobolus pyramidatus, please let us know.