Quick Facts

Quick facts

• Anchored Water Hyacinth (Eichhornia azurea) is a mat-forming perennial aquatic plant typically rooted in mud.
• It occurs in wetlands and irrigation channels, and in mud along rivers, lakes, marshes and canals.
• It is native to Central and South America and does not yet occur in Australia.
• Due to the worldwide weed status of Anchored Water Hyacinth and its close relative Water Hyacinth (E. crassipes), species of Eichhornia have been designated as prohibited imports in various countries, including Australia.
• Prevention of the establishment of Anchored Water Hyacinth is the best form of control.

What Does It Look Like?

What is it?

Anchored Water Hyacinth (Eichhornia azurea) is a mat-forming perennial (long lived) aquatic plant typically rooted in mud. Vegetative stems elongate, growing up to and at the water surface, with leaves above and below the water. Leaves below the water, or in heavily shaded areas, are linear, about 6–20 cm long and 0.5–1 cm wide, stalkless, with a blunt tip and alternately arranged in two rows on the stem. The leaves above the water are rounded, 5–16 cm long and 2–16 cm wide, with a slender stalk.

Flowering stems are upright and 8–12 cm above the water. The flower is a spike with several flowers along a hairy stem. The flowers are funnel-shaped with six toothed petals each 1–3 cm long. The flowers are mostly lavender blue or white with deep purple centres. The uppermost petal has a distinct yellow spot (Scher undated). Individual flowers are open for one day only (Johnson undated).

The fruit is a capsule with numerous seeds. The seeds are oblong to narrowly oblong in outline, measuring 1.5–2.6 mm long, 0.3–0.9 mm wide and thick, with about 10 longitudinal ridges or membranous wings evenly spaced around them (Scher undated).

For further information and assistance with identification of Anchored Water Hyacinth, contact the herbarium in your state or territory.

Flower colour

Blue, White, Purple

Growth form (weed type/habit)

Aquatic

Where it currently grows? Preferred habitat

Anchored Water Hyacinth occurs in wetlands and irrigation channels, and in mud along rivers, lakes, marshes and canals (Johnson undated; Scher undated). It can be rooted in mud or clay to a depth of 10–15 metres in water courses and dams (Johnson undated).

Are there similar species?

Anchored Water Hyacinth (E. azurea) and Water Hyacinth (E. crassipes) are very similar, but Anchored Water Hyacinth is rooted in the mud rather than free-floating and the leaf stalks of Anchored Water Hyacinth are always slender, whereas those of Water Hyacinth have bladder-like swellings, bulbous or elongate, which enable the plant to float. As the Water Hyacinth plants become more densely packed, the leaf stalks produced are longer and thinner (Parsons & Cuthbertson 2001; Winterton & Scher 2007; Johnson undated).

Anchored Water Hyacinth is also similar to the native plant Monochoria cyanea which is a subtropical species found in northern Western Australia, the Northern Territory and Queensland, with isolated occurrences in New South Wales (AVH 2008). Anchored Water Hyacinth is distinguished by the larger flowers, a longer and denser flower head, the upper petal with the yellow spot in the middle and almost round leaves, compared to the pointed, elliptic or egg-shaped leaves of M. cyanea (Jacobs 1993).

Why Is It A Weed?

What are its impacts?

Along with other aquatic plants, Anchored Water Hyacinth forms floating masses that obstruct navigation (Scher undated). It smothers the surface of creeks, lakes and other water bodies (Jordan 2007).

Native ecosystems: Its potential impact is similar to that of Water Hyacinth (Eichhornia crassipes) which obstructs waterways, interferes with irrigation systems and hydro-electric generation, removes oxygen from the water thereby reducing fish production, harbours mosquitoes and other vectors of disease, reduces areas available for waterbirds and causes significant water loss due to transpiration where there are dense infestations (Parsons & Cuthbertson 2001).

Anchored Water Hyacinth is closely related to Water Hyacinth which is considered one of the world's most serious aquatic weeds and is a declared noxious weed in many countries. Due to the weed status of Water Hyacinth and Anchored Water Hyacinth, several, and in some cases, all species of Eichhornia have been subsequently designated as prohibited imports in various countries, including Australia (Winterton & Scher 2007).

How does it spread?

Anchored Water Hyacinth is able to spread when part of the plant breaks away, moves downstream and new daughter plants are produced. Whole plants, stem fragments, capsules and seeds can be carried by water, in mud, on vehicles and by birds (Johnson undated; Scher undated). Humans contribute to dispersal by growing Anchored Water Hyacinth as an ornamental plant in ponds and aquaria and by the careless disposal of plants or plant fragments and seed (Parsons & Cuthbertson 2001).

What is its history in Australia?

Anchored Water Hyacinth is not known to occur in Australia (Johnson undated).

How To Manage It?

Best practice management

Anchored 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 Water Hyacinth in Australia but none are currently registered for Anchored Water Hyacinth.

Please see the Australian Pesticides and Veterinary Medicines Authority for chemical information http://www.apvma.gov.au 

Although large infestations of Water Hyacinth are controlled through mechanical harvesting, this may not be as effective for Anchored Water Hyacinth due to its anchored habit (Johnson undated).

Does it have a biological control agent?

NO

When does it grow? (lifecycle/growth calendar)

The growth calendar of Anchored Water Hyacinth is assumed to be similar to that of its close relative, Water Hyacinth (Eichhornia crassipes). Seeds germinate in spring and rapid growth occurs with rising temperatures (Parsons & Cuthbertson 2001). Anchored Water Hyacinth flowers in summer and autumn (Johnson undated). Flowering continues until aerial growth is killed by lowered temperatures, especially frosts. The rhizome survives winter and produces new aerial growth in spring (Parsons & Cuthbertson 2001).

After flowering, the heads bend over, submerging the developing fruit. The seeds drop to the bottom of the water. Most germination occurs in the mud on the water edges or on the bottom when the water dries up. The major propagation is by means of stolons (creeping stems) which produce daughter plants (Parsons & Cuthbertson 2001).

Where Is It Found?

Which states and territories is it found?

Not naturalised in any Australian state or territory.

What areas within states and territories is it found?

Anchored Water Hyacinth is not known to occur in Australia. It is a Class 1 declared pest plant in Queensland and a Class 1 noxious weed throughout New South Wales. As a notifiable weed in New South Wales, all outbreaks must be reported to the local council (Johnson undated).

Where does it originate?

Anchored Water Hyacinth is native to Mexico, Central America, South America and Jamaica (Scher undated).

National And State Weed Listings

Is it a Weed of National Significance (WONS)?

NO

Where is it a declared weed?

NSW, QLD, WA

Government weed strategies and lists – Weeds Australia

Is it on the National Alert List for Environmental Weeds?

NO

Government weed strategies and lists – Weeds Australia

Is it on the Agricultural Sleeper List?

NO

Government weed strategies and lists – Weeds Australia

Names And Taxonomy

Main scientific name

Eichhornia azurea

Other scientific names (synonyms)?

Pontederia azurea Swartz

Does it have other known common name(s)?

Rooted Water Hyacinth