Themeda arguens (L.) Hack., Poaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Common name(s): [more details]

English: Christmas grass, lesser tasselgrass

Habit:  grass

Description:  "Habit: Annual; caespitose. Culms erect; 20-120 cm long. Leaves mostly basal. Ligule an eciliate membrane; 1 mm long. Leaf-blade base broadly rounded. Leaf-blades flat, or conduplicate; 5-30 cm long; 4-7 mm wide. Leaf-blade apex acuminate. Synflorescence compound; fasciculate. Inflorescence composed of racemes; terminal and axillary; subtended by a spatheole; enclosed. Spatheole lanceolate; 2.5-3.5 cm long; scarious; without tubercles; glabrous. 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; 2 in the cluster. Pedicels oblong; 1 mm long; tip oblique. Sterile spikelets: Basal sterile spikelets represented by a single scale; 4 in number; forming an involucre about the fertile; with both pairs arising at about the same level; subsessile; 6-10 mm long; equaling fertile. Basal sterile spikelet glumes smooth; glabrous; lower glume muticous. Companion sterile spikelets well-developed; comprising 2 subequal glumes without lemmas; lanceolate; 6 mm long; shorter than fertile; separately deciduous. Companion sterile spikelet callus linear; 2-3 mm long; truncate. Companion sterile spikelet glumes herbaceous; glabrous; acuminate. Fertile spikelets: Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets elliptic; subterete; 8-10 mm long; falling entire; deciduous with accessory branch structures. Spikelet callus linear; 3 mm long; bearded; base pungent; attached obliquely. Spikelet callus hairs red. Glumes dissimilar; exceeding apex of florets; firmer than fertile lemma. Lower glume oblong; 1 times length of spikelet; coriaceous; dark brown; without keels; 7 -veined. Lower glume surface pilose; hairy above. Lower glume hairs dark brown. Lower glume apex truncate. Upper glume oblong; coriaceous; with membranous margins; 3 -veined. Upper glume surface pilose; hairy above. Upper glume margins ciliate. Upper glume hairs dark brown. Upper glume apex truncate. Florets: Basal sterile florets barren; without significant palea. Lemma of lower sterile floret oblong; 2.8 mm long; hyaline; ciliate on margins. Fertile lemma oblong; 3 mm long; hyaline; without keel; 1 -veined. Lemma apex entire; awned; 1 -awned. Principal lemma awn apical; geniculate; 50-70 mm long overall; with twisted column. Column of lemma awn hispidulous. Palea absent or minute. Flower: Anthers 1.4 mm long"  (GrassBase).

"Culms purple-tinged, 60-90 cm high; leaf blades 15-30 cm long, 3-5 mm broad; panicle compound, the leaflike spathes 3-8 cm. long, densely hairy; spikelets 5-7 mm long, awns about 5 cm long, twisted:  (Smith, 1979; p. 382).

Habitat/ecology:  "Introduced into Fiji for trial but appears to have escaped and become naturalized along roadsides in one or two isolated areas, where it is slowly spreading, between sea level and about 30 m"  (Smith, 1979; p. 382).

Propagation:  Seed

Native range:  Andaman and Nicobar islands, southeast Asia, Australia (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	Taveuni Island	introduced invasive cultivated	Smith, Albert C. (1979) (p. 382) Voucher cited: DA 16900
Fiji Fiji Islands	Viti Levu Island	introduced invasive cultivated	Smith, Albert C. (1979) (p. 382) Vouchers cited: DA 8324, DA 3127
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. 361)
Papua New Guinea Bismarck Archipelago	Bismarck Archipelago		Peekel, P. G. [translated by E. E. Henty] (1984) (p. 48)
Papua New Guinea Papua New Guinea (eastern New Guinea Island)	Papua New Guinea (eastern New Guinea Island)	native	Henty, E. E. (1969) (p. 184)
Philippines Philippine Islands	Philippine Islands		Hafliger, Ernst/Scholz, Hildemar (1980) (p. 138)

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	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Australia Australia (continental)	Queensland	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Cambodia Cambodia	Cambodia (Kingdom of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
China China	China (People's Republic of)		Hafliger, Ernst/Scholz, Hildemar (1980) (p. 138)
Indonesia Indonesia	Indonesia (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Malaysia Malaysia	Malaysia (country of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Singapore Singapore	Singapore (Republic of)	uncertain if introduced invasive	Chong, Kwek Yan/Tan, Hugh T. W./Corlett, Richard T. (2009) (p. 86) Weed of uncertain origin
Thailand Thailand	Thailand (Kingdom of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Vietnam Vietnam	Vietnam (Socialist 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
India (Indian Ocean offshore islands) Andaman Islands	Andaman Islands	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
India (Indian Ocean offshore islands) Nicobar Islands	Nicobar Islands	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)

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