Pacific Island Ecosystems at Risk (PIER)

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Lagarosiphon major
(Ridl.) Moss, Hydrocharitaceae
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Present on Pacific Islands?  no

Primarily a threat at high elevations?  no

Common name(s): [more details]

English: African elodea, African oxygen weed, curly waterweed, lagarosiphon, oxygen weed, South African oxygen-weed

French: elodée africaine, grand lagarosiphon

Habit:  aquatic herb

Description:  "Vigorous aquatic perennial.  Stems very fragile, to 1 m long, ± 3 mm in diameter, branched.  Leaves distant below, crowded above, alternate, recurved, stiff, opaque, acute to acuminate, c. 16 x 2 mm, margins minutely toothed.  Flowers 1 per spathe in axils of upper leaves; female flowers with filamentous perianth-tube c. 0.25 mm in diameter, to 6 cm long; perianth-segments pink, 1 mm long, transparent, with obvious midnerve; staminodia 3, less than styles, transparent, white, toothed at tip; styles 3, 1 mm long, bifid, red-purple. Lagarosiphon major may be distinguished from the related Egeria and Elodea by its alternate leaves" (Healy & Edgar, 1980; pp. 29-30). Note: All New Zealand collections have been from female plants. 

Habitat/ecology:  "Freshwater wetlands, lakes, ponds and slow rivers.  This plant grows best in nutrient rich waters. Where invasive, the plant forms dense weed beds in sheltered sites in water of 2-6.5 m depth.  The tall, closely packed stands exclude almost all other species, reducing light levels and affecting water chemistry.  The stems reach the water surface and dense mats may attract large herbivorous birds which may adversely affect the native flora"  (Weber, 2003; p. 226).

In New Zealand, "present in waters to a depth of 6 m" (Healy & Edgar, 1980; pp. 29-30).

Propagation:  Vegetative fragments (Weber, 2003; p. 226).

Native range:  Southern Africa, 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)
Australia (continental) introduced
National Herbarium of New South Wales (2013)
Victoria
Australia
Australia (continental)
New South Wales introduced
cultivated
National Herbarium of New South Wales (2013)
"Cultivated and established in some farm dams but doubtfully naturalized."
New Zealand
New Zealand
New Zealand (country) introduced
invasive
Healy, A. J./Edgar, E. (1980) (p. 29)
Voucher cited: R. Mason 526 (CHR 65739)
New Zealand
New Zealand
New Zealand (country) introduced
invasive
Owen, S. J. (1997)
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)
"Naturalisé/±envahissant"

Comments:  A declared noxious weed in the United States (GRIN). A serious problem in New Zealand (Healy & Edgar, 1980; pp. 29-30).

Control: 

Physical:  "Small infestations may be removed mechanically, but stem fragmentation must be avoided".

Chemical:  "Chemical control includes spraying with diquat approved for use in aquatic environments"  (Weber, 2003; p. 226).


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This page was created on 13 APR 2005 and was last updated on 17 MAY 2013.