Andropogon gayanus Kunth, Poaceae

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Present on Pacific Islands?  no

Primarily a threat at high elevations?  no

Risk assessment results: 

Australia: Reject, score: 8 (Go to the risk assessment)
Risk assessment from the Government of Queensland, Australia (PDF format)

Other Latin names:  Andropogon bisquamulatus Hochst.; Andropogon squamulatus Hochst.

Common name(s): [more details]

English: Rhodesian-bluegrass, gamba grass, tambuki grass

French: barbon

Spanish: pasto llanero

Habit:  grass

Description:  "Tufted perennial; culms 150-250 cm high.  Leaf-blades linear, 20-60 cm x 4-20 mm, acuminate.  Racemes paired, terminal and axillary, 4-9 cm long; pedicels and internodes cuneate, clavate, ciliate.  Sessile spikelet 5-8 mm long; lower glume flat on the back with a median groove; awn geniculate, 10-30 mm long.  Pedicelled spikelet 5-8 mm long, with a short, straight awn"  (Renvoize, 1984; p. 281).

"Habit: Perennial; caespitose. Culms 150-250 cm long. Ligule an eciliate membrane. Collar without external ligule, or with external ligule. Leaf-blade base tapering to the midrib; without a false petiole, or with a false petiole. Leaf-blades 30-60 cm long; 4-20 mm wide. Inflorescence:  Synflorescence compound; paniculate; lax. Inflorescence composed of racemes; terminal and axillary; subtended by a spatheole. Spatheole lanceolate; 6-8 cm long; herbaceous. Racemes 2; paired; 4-9 cm long. Rhachis fragile at the nodes; glabrous on surface; ciliate on margins. Rhachis internodes cuneate. Rhachis internode tip transverse; crateriform; with simple rim. Spikelets appressed; in pairs. Fertile spikelets sessile; 1 in the cluster. Companion sterile spikelets pedicelled; 1 in the cluster. Pedicels cuneate; 4-5 mm long; ciliate; tip lobed. Sterile spikelets: Companion sterile spikelets well-developed; male; elliptic; dorsally compressed; 5-8 mm long; as long as fertile. Companion sterile spikelet glumes chartaceous; glabrous, or pubescent, or villous; acute; awned; one glume awned, or both glumes awned; with 1-10 mm long awn. Companion sterile spikelet lemmas 2; enclosed by glumes. Fertile spikelets: Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets oblong; dorsally compressed; 5-8 mm long; falling entire; deciduous with accessory branch structures. Spikelet callus oblong; 1 mm long; pilose; base obtuse; inserted. Glumes: Glumes dissimilar; exceeding apex of florets; firmer than fertile lemma. Lower glume oblong; 1 times length of spikelet; coriaceous; 2-keeled; keeled laterally. Lower glume intercarinal veins distinct. Lower glume surface flat and with a longitudinal median groove; glabrous. Upper glume lanceolate; chartaceous; 1-keeled. Upper glume muticous, or mucronate. Florets: Basal sterile florets barren; without significant palea. Lemma of lower sterile floret lanceolate; hyaline; 2 -veined. Fertile lemma oblong; hyaline; without keel. Lemma apex lobed; 2 -fid; awned; 1 -awned. Principal lemma awn from a sinus; geniculate; 10-30 mm long overall; with twisted column. Column of lemma awn glabrous" (GrassBase).

Habitat/ecology:  Favors monsoonal climates. Forms dense stands, excluding native species. Acts to modify fire regimes. In the Northern Territory, Australia, "it has invaded riparian vegetation (creek banks and flood-plain fringes), degraded areas, roadsides, pastures and Eucalyptus savanna, in areas where annual rainfall exceeds 600 mm" (Smith, 1995, cited in Csurhes & Edwards, 1998; p. 139). "A vigorous, robust grass which can form dense stands.  A highly productive grass that increases fuel loads, cures later than the native annual grasses and produces intense, late dry season fires which seriously damage native woody species." (Smith, 2002; p. 69).

Propagation:  "Intentionally spread as a pasture species.  Seeds also blown short distances and spread along roadsides by vehicles, e.g. in mud and on radiators, slashers and graders." (Smith, 2002; p. 69).

Native range:  Tropical Africa; cultivated and naturalized elsewhere (GRIN).

Presence:

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	Csurhes, S./Edwards, R. (1998) (p. 139)
Australia Australia (continental)	Queensland	introduced invasive	Smith, Nicholas M. (2002) (p. 69)
Mexico Mexico	Mexico (United Mexican States)	introduced cultivated	U.S. Dept. Agr., Agr. Res. Serv. (2013) Veracruz

Comments:  Reported to be invasive in Venezuela (Csurhes & Edwards, 1998; p. 139).

Control: 

Physical:  Small patches may be dug out.

Chemical:  Spray with grass-selective herbicides (Weber, 2003; p. 45).