Weed Alert: Anchored water hyacinth
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Contacts and Further Information
If you find this weed please contact your local Council Weeds Officer or the nearest NSW Department of Primary Industries office immediately for positive identification and further assistance.
Alternatively call the NSW Weeds Hotline on 1800 680 244 or send an email to firstname.lastname@example.org
Anchored Water Hyacinth (Eichhornia azurea)
Anchored water hyacinth is a mat forming, aquatic perennial that occurs in wetlands and irrigation channels. It is closely related to the water hyacinth Eichhornia crassipes, a serious weed that is found growing in waterways in eastern Australia.
A native plant of South America, anchored water hyacinth is currently found throughout Central and South America, Africa and parts of Texas, where it has been declared as a noxious weed and is the subject of active eradication campaigns. Anchored water hyacinth is not known to occur in Australia.
Anchored water hyacinth (E. azurea) plants are usually rooted in mud, but are occasionally free floating. In contrast,water hyacinth (E. crassipes) looks very similar but is a free floating species.
Anchored water hyacinth can be identified by its petioles, which are smooth, not inflated like E. crassipes. Anchored water hyacinth is also similar to the native plant Monochoria cyanea which is a subtropical species rarely found in NSW.
StemsThe submersed vegetative stems are smooth and branched. Flowering stems are erect and 8–12 cm above the water.
LeavesThe aerial leaves are variable in size, generally very broad-ovate in shape, 5–16 cm long and 2–16 cm wide. Leaves below the water or in heavily shaded areas become linear-shaped between 6-20 cm long and about 1 cm wide.
FlowerThe flower is a spike with several flowers along a hairy stem. The flowers are funnelshaped with six toothed petals 1–3 cm long. The flowers are mostly white or lavender blue with deep purple centres. The uppermost petal has a distinct yellow spot (see over). Individual flowers are open for one day only.
The seeds are small and only 1–2 mm long.
Growth and Spread
Anchored water hyacinth is generally rooted in mud or clay along water courses and dams to a depth of 10–15 metres.
Reproduction is by seed and vegetatively. Anchored water hyacinth is able to spread when part of the plant breaks away and moves downstream and grows in a new area. It flowers in summer and autumn and seeds can be carried by water, in mud, on vehicles and by birds.
ControlAnchored water hyacinth is not known in Australia, so prevention of its establishment is the best form of control. Overseas, small infestations are removed by hand. There are several herbicides available for the control of E. crassipes in Australia but none are currently registered for E. azurea. Although large infestations of E. crassipes are mechanically harvested, this may not be as effective for anchored water hyacinth due to its anchored habit.
Watch out for and report any form of Anchored Water Hyacinth.
Eichhornia azurea is a Class 1 noxious weed throughout NSW under the NSW Noxious Weeds Act 1993. This weed must be eradicated from the land and the land must be kept free of the plant. As a notifiable weed, all outbreaks must be reported to the local council.
If you have seen this plant, please report it to your Council Weeds Officer or NSW Department of Primary Industries for positive identification.
Alyssa Schembri, Stephen Johnson and Andrew Petroeschevsky.
ReferencesThe information for this Primefact was taken from the following sources.
- Burton, J. (2005) Water hyacinth Eichhornia crassipes. Agfact. P7.6.43 third edition. NSW DPI.
- Invasive.org (2006) Eichhornia (www.invasive.org) [Accessed 29 November 2006].
- Flora of North America. Eichhornia azurea (www.efloras.org) [Accessed 29 November 2006].