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Common Name Lagarosiphon Botanical Name Lagarosiphon major (Ridley) Moss Status Lagarosiphon is one of only fourteen weeds proclaimed as State Prohibited Weeds in Victoria. This is the highest category to which a noxious weed can be allocated and means that lagarosiphon is to be eradicated if possible from the State. Origin Lagarosiphon is native to southern Africa. It has been distributed worldwide and probably throughout Australia by use in aquariums, however naturalised populations are not known in Victoria. Description Lagarosiphon is a perennial freshwater herb with long branching stems arising from fixed or free-floating rhizomes. Stems - 3 to 5 mm in diameter, much branched, brittle, up to 5 m long; interweave to form large mats below the water surface. Leaves - stiff, 5 to 20 mm long, 2 to 3 mm wide, margins finely saw-toothed; curved downward and directly attached to the stem in an alternate spiral arrangement; densely spaced but sparser towards the base of the stems. Flowers - individual plants bear either male or female flowers. Very small, solitary female flowers grow from between the leaves and rhizomous stems. Female flowers remain attached to the plant by a thread like tube and float to the surface. Male flowers become detached and float to the surface. Male plants are not known in Australia. Seeds - not produced in Australia because the plants are unisexual and only females are known in Australia. Roots - fine; originate from nodes along the lower part of the stems.  Figure 1: Lagarosiphon. Life Cycle Vegetative reproduction of lagarosiphon in Australia follows a similar pattern to the sexual life cycle in its native environment. Flowering occurs from summer to early autumn and during the winter months when lagarosiphon becomes dormant. The vegetative parts which can reproduce include dormant shoots, rhizomes, and buds on stem fragments. Dispersal In Australia the main method of potential spread appear to be through use in aquariums and disposal of unwanted aquarium life into fresh water streams and water supplies. The stems fragment readily and the fragments can be carried long distances in moving water and eventually take root and form new plants. General Lagarosiphon is an extremely invasive water weed, able to tolerate shaded conditions and root into the sediment at the bottom of a water body or free float on the surface. Lagarosiphon can block hydro-electric schemes if left uncontrolled. Chemical Control No herbicide products are registered in Victoria to control this weed. Important Any person who believes they have located an infestation of lagarosiphon, regardless of the area, please notify a Catchment Management Officer at a local office of the Department of Natural Resources and Environment. Reference Parsons, W.T. and Cuthbertson, E.G. (1992) Noxious Weeds of Australia. Melbourne, Inkata Press. Acknowledgements Drafted by N. Freeman, edited by R. Williamson; Information & Assessment KTRI, 1996. Revised by I. Faithfull, January 1998. This note replaces note number PPA0005 The advice provided in this publication is intended as a source of information only. Always read the label before using any of the products mentioned. The State of Victoria and its employees do not guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular purposes and therefore disclaims all liability for any error, loss or other consequence which may arise from you relying on any information in this publication. |
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© The State of Victoria, 1996 - 2008.
This document was published on 26/10/2008.