Phalaris aquatica L., Poaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Other Latin names:  Phalaris nodosa L.; Phalaris stenoptera Hack.; Phalaris tuberosa L.

Common name(s): [more details]

Chinese: shui ge cao

English: Harding grass, Towoomba Canary grass, bulbous Canary grass, tuberous canarygrass

French: alpiste bulbeux, herbe de Harding, phalaris tubéreux

Spanish: rabillo de cordero

Habit:  grass

Description:  "Habit: Perennial; caespitose. Rhizomes short. Culms 100-150 cm long; not swollen at the base, or swollen at the base; forming an ovoid corm. Ligule an eciliate membrane. Leaf-blades 10-30 cm long; 3-8 mm wide. Inflorescence a panicle. Panicle spiciform; oblong; 1.5-11 cm long; 1-2.5 cm wide. Spikelets solitary. Fertile spikelets pedicelled. Spikelets comprising 2 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets obovate; laterally compressed; compressed strongly; 4.5-7.5 mm long; breaking up at maturity; disarticulating below each fertile floret. Glumes persistent; similar; exceeding apex of florets; thinner than fertile lemma. Lower glume elliptic; 4.5-7.5 mm long; 1 times length of upper glume; chartaceous; 1-keeled; winged on keel; winged above; 3 -veined. Lower glume apex acute. Upper glume elliptic; 4.5-7.5 mm long; 1.5-1.7 times length of adjacent fertile lemma; chartaceous; 1-keeled; winged on keel; winged above; 3 -veined. Upper glume apex acute. Florets: Basal sterile florets dissimilar; developed, or with vestigial lower floret; barren; without significant palea; attached to and deciduous with the fertile. Lemma of lower sterile floret subulate; 0-0.5 mm long. Lemma of upper sterile floret subulate; 0.2-2.2 mm long; pubescent. Fertile lemma elliptic; laterally compressed; 3-4.5 mm long; cartilaginous; shiny; keeled; 5 -veined. Lemma surface pubescent. Lemma apex acute. Palea cartilaginous; 2 -veined; without keels. Palea surface pubescent. Flower: Anthers 3. Ovary glabrous. Caryopsis with adherent pericarp; 2.2-2.5 mm long. Hilum linear"  (World Grass Species).

Habitat/ecology:  "Grass- and heathland, riparian habitats, freshwater wetlands, coastal beaches.  Mature plants of this grass develop an extensive and deep root system, thereby outcompeting native species.  It forms dense stands that exclude all other vegetation and impede recruitment of native shrubs and trees.  The grass accumulates large amounts of dead biomass and increases fire hazards"  (Weber, 2003; p. 317).

Propagation:  Seed, dispersed by water and animals (Weber, 2003; p. 317).

Native range:  Macaronesia, northern Africa, Europe, western Asia (GRIN).

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Australia (Pacific offshore islands) Lord Howe Island	Lord Howe Island	introduced invasive cultivated	Orchard, Anthony E., ed. (1994) (p. 23) "Probably introduced for fodder". Voucher cited: A.C. Beauglehole 5436 (CANB, NSW)
State of Hawaii Hawaiian Islands	Hawai‘i (Big) Island	introduced invasive	Herbst, Derral R./Clayton, W. D. (1998) (p. 33) Voucher cited: Ewart 253 (BISH)
State of Hawaii Hawaiian Islands	Maui Island	introduced invasive	Herbst, Derral R./Clayton, W. D. (1998) (p. 33) East Maui. Vouchers cited: Hobdy 1654 (BISH), Hosaka 2449 (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)	Australia (continental)	introduced invasive	U.S. Dept. Agr., Agr. Res. Serv. (2013)
China China	China (People's Republic of)	introduced cultivated	Zhengyi, Wu/Raven, Peter H./Deyuan, Hong (2013) Introduced for grazing; Yunnan.
New Zealand New Zealand	New Zealand (country)	introduced invasive	Edgar, E./Connor, H. (2000) (p. 352) "Waste ground, roadsides especially on drain margins, and coastal hillsides".

Control:  Additional control information from the Bugwood Wiki.

Physical:  "Small plants can be dug out, rhizomes must be removed.  Large stands are regularly slashed or burned to reduce seed production, a follow-up program is necessary to control regrowth and seedlings.  Close mowing or clipping late in the growing season reduces the vigor of the grass".

Chemical:  "A pre-emergence herbicide to control this grass is sulfumeturon"  (Weber, 2003; p. 317).