Weed Identification

Australia > > Lagarosiphon


Lagarosiphon major


IMPORTANT: IF YOU SUSPECT THE PRESENCE OF THIS PLANT, PLEASE REPORT IT BY CALLING 1800 084 881 (local call cost anywhere in Australia).

Family: Hydrocharitaceae.

Form: Water plant

Origin: Native of southern Africa.

Flowers/Seedhead: Flowers: Male and female flowers on separate plants. Female flowers about 3 mm wide, attached to a thread like flower tube (hypanthium) that floats (still attached to the plant) to the water surface. Male flowers (not yet recorded in Australia) separate and float to the surface.

Description: Perennial rhizomatous freshwater submerged plant. Stems branched, to many metres in length. Leaf margins minutely toothed. Leaves crowded near the end of branches, but usually well spaced toward the plant base.

Distinguishing features: Distinguished by leaves that are strongly downward curving and spirally arranged on the stem.

Dispersal: By rhizomes, natural fragmentation and by pieces after mechanical disturbance. Seeds not known to be produced in Australia.

Confused With: Canadian Pondweed Elodea canadensis, Hydrilla Hydrilla verticillata and Egeria densa. These species have leaves in whorls (clusters around the same point on the stem).

Leaves are crowded except at base,
spirally arranged (not in whorls) & each
leaf is strongly downward curving. The
spiral leaf arrangement separates
Lagarosiphon from Egeria, Hydrilla
& Elodea
photo R. Brayne

Notes: A hardy aquatic that can grow in deep clear water and clog intake valves of hydro-electric stations. Major aquatic weed in New Zealand. Will withstand low light levels, and thrives in clear water to more than 6 m deep. Recorded from aquaria and from farm dams near Newcastle and near Melbourne but not known to be naturalised.


    Noxious Weeds of Australia. W. Parsons and E. Cuthbertson, 1992, pages 7173. Waterplants in Australia, G. Sainty and S. Jacobs, 3rd edition, 1994, pages 8889.

This weed has been included in the WEEDeck field guide as card W11

More information about WEEDeck is available from Sainty & Associates Pty. Ltd.


Australia > > Lagarosiphon


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