Potamogeton crispus L., Potamogetonaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Common name(s): [more details]

Chinese: zu cao

English: curled pondweed, curly pondweed, curly-leaved pondweed, curlyleaf pondweed, river weed

French: potamot crépu

Habit:  aquatic herb

Description:  "Submersed perennial herbs with rhizomes creeping above and below the mud and with fibrous roots on the lower side of each node.  Stems and rhizomes often 3 to 4 m long, richly branched, leaves alternate.  The small perfect flowers are on pedunculate axillary spikes, fruiting carpels are one-seeded, indehiscent seeds are without endosperm, the embryo with a large "foot," and the plumule enclosed by the cotyledon.  In P. Crispus the slender stems are laterally compressed, tending to be 4-angled with furrows on broader sides that are 0.5 to 2.5 mm wide; rhizomes may be buff or reddish in color; leaves alternate, sessile, narrowly lanceolate to linear-oblong, obtuse, serrulate, undulate to strongly wavy at margins, bright green to dark green, may be reddish, 0.75 to 1.5 cm wide, 10 cm long, free stipular sheath, stipular sheath 5 to 15 mm long, truncate, often disintegrating; inflorescence in 3 to 5 whorls of flowers, spike 1 to 2 cm long; fruiting carpels 2 to 7 mm long, 1.5 to 3 mm wide, dark olive to brownish, sometimes with strongly developed dorsal keel, conspicuous or somewhat curved beak, fruit body with smooth to strongly tuberculate sides"  (Holm et al., 1997; pp. 626-627).

Habitat/ecology:  Found in ditches, streams and impoundments.  Mainly a freshwater plant, but will tolerate some brackishness.  (Holm et al., 1997; pp. 629, 631).

In Fiji, "a naturalized weed in low elevation ponds and rivers, sometimes carried into saltwater bays by floods.  It is a submerged herb, sometimes rooting at depths as much as 3 m., or found at the edges of fast-flowing steams and rivers, often in thick beds, and often associated with Hydrilla verticillata.  It has become a serious weed, especially in the Rewa River system, because of its tendency to become entangled in the propellers of small boats"  (Smith, 1979; pp. 130-131).

Propagation:  Floating seed and asexually by turions (specialized vegetative buds) and stem fragments (Holm et al., 1997; pp. 632-637).

Native range:  Europe, Asia, northern Africa, 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	Viti Levu Island	introduced invasive	Smith, Albert C. (1979) (p. 132) Vouchers cited: DA 16631; DA 16630, DA 14527, DA 16613, DA 11543, DA 16626, DA 16623, DA 16622, DA 16602, DA 11828, DA L. 15599
Philippines Philippine Islands	Philippine Islands		Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 630)

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)	New South Wales		Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 630)
Australia Australia (continental)	Northern Territory		Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 630)
Australia Australia (continental)	Queensland		Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 630)
China China	China (People's Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Indonesia Indonesia	Indonesia (Republic of)		Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 630)
Japan Japan	Japan	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
North Korea North Korea	North Korea (Democratic People's Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
South Korea South Korea	South Korea (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
New Zealand New Zealand	New Zealand (country)	introduced invasive	Healy, A. J./Edgar, E. (1980) (p. 37) "In lakes, ponds, rivers, streams and water races".
Thailand Thailand	Thailand (Kingdom of)		Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 630)

Control:  See "Biology and control of aquatic plants: A best management practices handbook" for control information (large file, PDF format).