Common name: Lagarosiphon, Oxygen Weed
Lagarosiphon major (Ridl.) Moss APNI*
Description: Submerged rhizomatous aquatic perennial with branched stems to c. 5 m or sometimes more ong; usually attached but able to survive submerged and free-floating.
Leaves alternate, well spaced below, closely spaced above, recurved, 0.5–2 cm long, 2–3 mm wide, margins minutely toothed.
Flowers unisexual; male flowers not recorded in Aust. Female flowers with spathe usually 3.5, up to 5.5 mm long; hypanthium thread-like, length varies according to water depth; perianth segments 1–2 mm long; styles purple.
Flowering: during warmer months.
Distribution and occurrence: Cultivated and established in some farm dams but doubtfully naturalized in N.S.W. Native of Afr.
NSW subdivisions: *NC
Other Australian states: *Vic.
This species can survive free-floating in deep cold water such as in water storages. It is a very aggressive weed of still and slow-moving waterways in New Zealand and Europe. Potential distribution (based on suitable habitat conditions) in Australia, plant details and weed properties are provided in the Weeds in Australia profile compiled by P.G. Kodela (2008).
Text by S.W.L. Jacobs; revised by P.G. Kodela (July 2012)
Taxon concept: Flora of NSW 4 (1993)
APNI* Provides a link to the Australian Plant Name Index (hosted by the Australian National Botanic Gardens) for comprehensive bibliographic data
***The AVH map option provides a detailed interactive Australia wide distribution map drawn from collections held by all major Australian herbaria participating in the Australian Virtual Herbarium project.