Themeda quadrivalvis (L.) Kuntze, Poaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Risk assessment results:  Evaluate, score: 1 (Go to the risk assessment)

Common name(s): [more details]

Chinese: zhong hua jian

English: grader grass, habana grass, kangaroo grass

French: herbe Saint-Paul, herbe de Javel, herbe de bondé, herbe kangourou

Habit:  grass

Description: 

Genus: "Annuals or perennials, the culms usually robust; panicle compound, leafy, the inflorescence a fan-shaped cluster of several racemes each subtended by a leaflike spathe, the whole subtended or partially enclosed by a larger spathe; racemes of 2 approximate pairs of sessile, awnless, male or sterile spikelets and a single, fertile, awned spikelet with a pair of stalked, sterile or male spikelets forming a pointed callus below the fertile one"  (Smith, 1979; pp. 382-383).

Species:  "Annual, the culms 45-150 cm high, leaf blades 10-30 cm long, 5-6 mm broad; panicle 10-30 cm long, the leaflike spathes 1-3 cm long, sparsely hairy along margins; spikelets about 5 mm long, the awns 3-5 cm long"  (Smith, 1979; pp. 382-383).

"Habit: Annual. Culms erect, or geniculately ascending; 30-200 cm long; 4-6 mm diam.; 5-7 -noded; with prop roots. Culm-nodes glabrous. Leaf-sheaths keeled. Ligule an eciliate membrane; 2-2.5 mm long. Leaf-blades 7-30 cm long; 3-6 mm wide; flaccid. Leaf-blade surface smooth, or scaberulous; rough adaxially; glabrous, or pilose. Leaf-blade margins scabrous. Leaf-blade apex acute, or acuminate. Inflorescence: Synflorescence compound; fasciculate; 15-50 cm long. Inflorescence composed of racemes; terminal and axillary; subtended by a spatheole; enclosed. Spatheole lanceolate; 7.5-16 cm long; scarious; red; without tubercles, or tuberculate; glabrous, or pilose. Peduncle 1.3 cm long. Racemes 1; single; cuneate; bearing few fertile spikelets; bearing 1 fertile spikelets on each. Rhachis fragile at the nodes. Spikelets in threes (basal paired). Fertile spikelets sessile; 1 in the cluster. Companion sterile spikelets pedicelled; 1 in the cluster. Pedicels oblong; 0.5 mm long. Sterile spikelets: Basal sterile spikelets well-developed; 4 in number; forming an involucre about the fertile; with both pairs arising at about the same level; subsessile; linear, or lanceolate; 4.5-6 mm long; equaling fertile. Basal sterile spikelet glumes chartaceous; tuberculate on margins and setose on margins; lower glume muticous. Companion sterile spikelets well-developed; comprising 2 subequal glumes without lemmas; linear; 5-6 mm long; as long as fertile; separately deciduous. Companion sterile spikelet callus linear. Companion sterile spikelet glumes smooth; glabrous. Fertile spikelets Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets elliptic; subterete; 5-5.5 mm long; falling entire; deciduous with accessory branch structures. Spikelet callus oblong; bearded; base obtuse; attached obliquely. Spikelet callus hairs red. Glumes: Glumes dissimilar; exceeding apex of florets; firmer than fertile lemma. Lower glume oblong; 1 times length of spikelet; coriaceous; much thinner above; dark brown; without keels; 7-9-veined. Lower glume surface puberulous. Lower glume apex obtuse. Upper glume oblong; 3-veined. Upper glume margins ciliolate. Florets: Basal sterile florets barren; without significant palea. Lemma of lower sterile floret lanceolate; 3 mm long; hyaline; 1 -veined; without lateral veins. Fertile lemma linear; hyaline; without keel; 1-veined. Lemma apex entire; awned; 1-awned. Principal lemma awn apical; geniculate; 10-45 mm long overall; with twisted column. Column of lemma awn hirtellous. Palea absent or minute" (GrassBase).

Habitat/ecology:  In Fiji, "naturalized and moderately common, at least on Viti Levu, along roadsides and in waste places near sea level"  (Smith, 1979; pp. 382-383). In New Caledonia, "étant considéré comme indigène; parfois très envahissant en pâturages, notamment dans la région de Ouégoa" (MacKee, 1994; p. 63). In Australia, "prominent along roadsides and in disturbed areas.  Can invade native pastures or grassland and seriously reduce diversity.  Becomes a serious problem when areas are overgrazed or disturbed.  In Queensland it is a weed of crops such as sugar cane, lucerne, legume seed crops and pastures." (Smith, 2002; p. 78).

Propagation:  "Large seeds are produced in prolific numbers but do not normally travel great distances by natural means.  Usually dispersed on clothing, fur, etc.  Road graders have also been responsible for spreading seeds along roadsides.  Dispersal has also been by contaminated pasture seed and in mud carried by vehicles and machinery." (Smith, 2002; p. 78).

Native range:  India (Smith, 1979; pp. 382-383). India and Nepal, naturalized elsewhere (GRIN).

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	Viti Levu Island	introduced invasive	Smith, Albert C. (1979) (pp. 382-383) Vouchers cited: Greenwood 137, DA 8223, DA 8240, DA 10710, DA 8999, DA 7154, DA 7155, DA 7156, DA 7161, DA 8145, DA 7941
New Caledonia New Caledonia Archipelago	Île Grande Terre	introduced invasive	Gargominy, Oliver/Bouchet, Philipe/Pascal, Michel/Jaffre, Tanguy/Tourneu, Jean-Christophe (1996) (p. 381) Parfois très envahissante en pâturages, notamment dans la région de Ouégoa. A connu une explosion brutale en 1995; parfois considérée comme indigène.
New Caledonia New Caledonia Archipelago	Île Grande Terre	introduced invasive	Tassin, Jacques (2005)
New Caledonia New Caledonia Archipelago	Île Grande Terre	introduced invasive	MacKee, H. S. (1994) (p. 63)

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. 78)
Australia Australia (continental)	Queensland	introduced invasive	Smith, Nicholas M. (2002) (p. 78)
China China	China (People's Republic of)		Zhengyi, Wu/Raven, Peter H./Deyuan, Hong (2013) Dry hill slopes; 400-2000 m. Guangdong, Guangxi, Guizhou, Hainan, Yunnan.
Indonesia Indonesia	Indonesia (Republic of)		Zhengyi, Wu/Raven, Peter H./Deyuan, Hong (2013)
Thailand Thailand	Thailand (Kingdom of)		Zhengyi, Wu/Raven, Peter H./Deyuan, Hong (2013)
Vietnam Vietnam	Vietnam (Socialist Republic of)		Zhengyi, Wu/Raven, Peter H./Deyuan, Hong (2013)

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. 361)

Comments:  A declared noxious weed in the Northern Territory, Australia (Smith, 2002; p. 78).

Control:  If you know of control methods for Themeda quadrivalvis, please let us know.