(Ridl.) Moss, Hydrocharitaceae |
Present on Pacific Islands? no
Primarily a threat at high elevations? no
Common name(s): [more details]
English: African elodea, African oxygen weed, South African oxygen-weed, curly waterweed, lagarosiphon, 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) |
New South Wales |
introduced
cultivated |
National Herbarium of New South Wales (2013)
"Cultivated and established in some farm dams but doubtfully naturalized." |
Australia
Australia (continental) |
Australia (continental) |
introduced
|
National Herbarium of New South Wales (2013)
Victoria |
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).