Hyparrhenia rufa (Nees) Stapf, Poaceae

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Present on Pacific Islands?  yes

Threat only at high elevations?  no

Risk assessment results:  Reject, score: 7 (Go to the risk assessment)

Common name(s): [more details]

English: giant thatching grass, jaragua grass, thatch grass, thatching grass

French: herbe rouge

Hindi: jaragua

Spanish: yaragua

Habit:  grass

Description:  "Perennial or sometimes annual [grass]; culms densely tufted, forming large clumps 3-25 dm tall, nodes long-pilose. Sheaths sparsely long-pilose, the hairs white, appressed at base, upper sheaths glabrous but with margins ciliate and hairs readily deciduous; ligule a firm, brownish membrane, 1-2.5 mm long; blades flat, glabrous or upper surface hirsute, 30-60 cm long, 2-8 mm wide, narrowed at base. Inflorescences large, paniculate, with numerous branches, the branches lax or contracted, fasciculate, 5-80 cm long, spathes linear-lanceolate, becoming reddish and rolled around the peduncle, 3-5 cm long, sparsely to densely long-pilose, racemes dull yellow, sometimes red-tinged, (1.5-)2-2.5 cm long, with (7-)9-14 awns per raceme pair, the awns rarely reflexed, with 1 homogamous pair of spikelets at the base of the lowest or of both racemes, raceme-bases unequal, sometimes connate, the upper one 2-3.5(-4) mm long, glabrous, rarely with a few long hairs, the articulation with the peduncle apex glabrous; sessile spikelet (3-)3.5-4.5(-5) mm long, glabrous to pubescent, but usually sparsely covered with stiff red hairs, usually glossy; pedicellate spikelet acute or rarely mucronate, callus 0.2-0.8 mm long, short and rounded to cuneate, narrowly truncate; lemma slender, filiform, ca. 2 mm long, membranous, awn arising from bifid apex, strongly twisted, geniculate, pubescent; ellipsoid to ovoid, ca. 3 mm long" (Wagner et al., 1999; p. 1554).

Description from World Grass Species.

Habitat/ecology:  "Grows in sandy or loamy soil.  Fond on disturbed ground and roadsides." (Smith, 2002; p. 75). Dry to mesic roadsides, disturbed areas. May carry wildfire. In Fiji, "reported as escaped and naturalized, but apparently it is uncommon" (Smith, 1979; pp. 380-381). In Hawai‘i, "naturalized and common along roadsides and in cultivated fields, 10-660 m" (Wagner et al., 1999; p. 1554).

Propagation:  "Seeds are dispersed by wind.  Spread is also by vehicles and machinery, e.g. road graders." (Smith, 2002; p. 75).

Native range:  Tropical and south Africa.

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Fiji Fiji Islands	Fiji Islands	introduced invasive	Smith, Albert C. (1979) (pp. 380-381) Not common. Vouchers cited: DA 3586, DA 3632, DA 7235, DA 8315.
Fiji Fiji Islands	Viti Levu Island		Bishop Museum (Honolulu) (1952) (voucher ID: BISH 31695) Taxon name on voucher: Hyparrhenia rufa (Nees) Stapf
French Polynesia Society Islands	Raiatea (Havai) Island	introduced invasive	Welsh, S. L. (1998) (p. 338) Vouchers cited: Florence 4620, BRY 25740, BRY 26371
French Polynesia Society Islands	Raiatea (Havai) Island		Bishop Museum (Honolulu) (1982) (voucher ID: BISH 492124) Taxon name on voucher: Hyparrhenia rufa (Nees) Stapf
French Polynesia Society Islands	Tahiti Island	introduced invasive	Welsh, S. L. (1998) (p. 338) Voucher cited: Florence 3388
French Polynesia Society Islands	Tahiti Island		Bishop Museum (Honolulu) (1983) (voucher ID: BISH 554433) Taxon name on voucher: Hyparrhenia rufa (Nees) Stapf
Guam Guam Island	Guam Island	introduced	Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1987) (p. 44)
State of Hawaii Hawaiian Islands	Hawai‘i (Big) Island	introduced invasive	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 1554) Voucher cited: Judd s. n. (BISH)
State of Hawaii Hawaiian Islands	Kaua‘i Island	introduced invasive	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 1554)
State of Hawaii Hawaiian Islands	Maui Island	introduced invasive	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 1554)
State of Hawaii Hawaiian Islands	Moloka‘i Island	introduced invasive	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 1554)
State of Hawaii Hawaiian Islands	O‘ahu Island	introduced invasive	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 1554)

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)	Northern Territory	introduced invasive	Smith, Nicholas M. (2002) (p. 75)
Australia Australia (continental)	Queensland	introduced invasive	Smith, Nicholas M. (2002) (p. 75)
Colombia Colombia	Colombia (Republic of)		Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. (1979) (pp. 187-188)
Costa Rica Costa Rica	Costa Rica (Republic of)	introduced	U.S. Dept. Agr., Agr. Res. Serv. (2007)
Ecuador (Mainland) Ecuador	Ecuador (Republic of) (continental)		Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. (1979) (pp. 187-188)
Guatemala Guatemala	Guatemala (Republic of)		Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. (1979) (pp. 187-188)
Honduras Honduras	Honduras (Republic of)		Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. (1979) (pp. 187-188)
Thailand Thailand	Thailand (Kingdom of)		Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. (1979) (pp. 187-188)

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	uncertain if native	Lavergne, Christophe (2006) "Weed (indigène?)"
Mascarene Islands Mascarene Islands (Mauritius, La Reunion, Rodrigues)	Mascarene Islands	introduced	U.S. Dept. Agr., Agr. Res. Serv. (2007)
Mauritius Mautitius Islands (Mauritius and Rodrigues)	Mauritius Island		Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. (1979) (pp. 187-188)

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)	USA (Florida)	introduced	U.S. Dept. Agr., Agr. Res. Serv. (2007)

Comments:  A serious weed in Colombia (Smith, 2002; p. 75). An aggressive weed in Costa Rica.

Additional information:  Report (PDF format) from US Geological Survey, Biological Resources Division, Haleakala Field Station, Hawaii "Plants of Hawaii".

Additional online information about Hyparrhenia rufa is available from the Hawaiian Ecosystems at Risk project (HEAR).

Taxonomic information about Hyparrhenia rufa may be available from the Germplasm Resources Information Network (GRIN).

References:

Bishop Museum (Honolulu). 1952. Voucher specimen #BISH 31695 (Parham, B.E. 3632).

Bishop Museum (Honolulu). 1982. Voucher specimen #BISH 492124 (Florence, J. 3388).

Bishop Museum (Honolulu). 1983. Voucher specimen #BISH 554433 (Florence, J. 4620).

Cronk, Q. C. B./Fuller, J. L. 2001. Plant invaders. Earthscan Publications, Ltd., London. 241 pp.

Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce. 1987. A geographical checklist of the Micronesian monocotyledonae. Micronesica 20:1-126.

Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. 1979. A geographical atlas of world weeds. John Wiley & Sons, New York. 391 pp.

Lavergne, Christophe. 2006. List des especes exotiques envahissantes a La Reunion. Unpublished manuscript (Excel file). .

Smith, Albert C. 1979. Flora Vitiensis nova: a new flora of Fiji. National Tropical Botanical Garden, Lawai, Kauai, Hawaii. Volume 1. 494 pp.

Smith, Nicholas M. 2002. Weeds of the wet/dry tropics of Australia - a field guide. Environment Centre NT, Inc. 112 pp.

U.S. Dept. Agr., Agr. Res. Serv. 2007. National Genetic Resources Program. Germplasm Resources Information Network (GRIN). Online searchable database.

Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. 1999. Manual of the flowering plants of Hawaii. Revised edition. Bernice P. Bishop Museum special publication. University of Hawai‘i Press/Bishop Museum Press, Honolulu. 1919 pp. (two volumes).

Welsh, S. L. 1998. Flora Societensis: A summary revision of the flowering plants of the Society Islands. E.P.S. Inc., Orem, Utah. 420 pp.