Mimosa pigra is a much–branched, thorny legume shrub that grows along waterways and invades freshwater wetlands and swamps. Originally from Central and South America, it was planted at the Darwin Botanic Gardens in the late 1800’s as a curiosity. Its invasive nature was not realised until the 1950’s when it was observed growing in drainage lines and creeks.
It forms dense, impenetrable thickets, 3-6 meters high. If left untreated Mimosa pigra has the ability to restrict access to water impacting on recreational activities, tourism, stock watering points, pasture quality and mustering.
The Northern Territory has the most extensive infestation of Mimosa pigra, which covers an approximate area of 80,000 ha. In 2001 a local landholder discovered Mimosa pigra growing at Lake Proserpine (Peter Faust Dam). This infestation is one of only two infestations found outside of the Northern Territory, the other being on the Western Australian/Northern Territory Border.
Mimosa pigra is spread via water, contaminated soil, vehicles, boats, boat trailers, animals and through suckering. This species is a Weed of National Significance and a class 1 declared weed in Queensland meaning that it is a serious offence to introduce, keep or supply Mimosa pigra in Queensland without a permit issued by Biosecurity Queensland. Penalties of up to $80,000 apply.
Project Description and Project Partners
As a result of the extensive damage that Mimosa pigra can have on the natural environment the Mimosa pigra Stakeholder group was formed in 2001 and aims to stop the invasion of our waterways by Mimosa pigra. Through a collaborative effort between the members of the Stakeholder group Reef Catchments (Mackay Whitsunday Isaac) Limited has secured ongoing funding to ensure the continuation of successful containment and eradication activities.
The current two year program “the eradication of Mimosa pigra Outlier in Central Queensland” has been funded through the Australian Government’s Caring for our Country Initiative. This program aims to reduce the impact and spread of a high priority outlier infestation of a Weed of National Significance over the next two years by continuing the eradication of Mimosa pigra from Lake Proserpine.
This project is being carried out at Lake Proserpine also known as the Peter Faust Dam. This dam was completed in 1990 to provide water for the Proserpine irrigation area and flood mitigation within the Proserpine region. At full capacity the dam covers an area of 43,355 ha and has a storage capacity of 491,400 megalitres. The catchment area for Lake Proserpine is 260 km.
The major land uses at the dam include grazing and forestry, National Parks and Reserves and water storage. Lake Proserpine flows into the Proserpine River which in turn flows into the Goorganaga Plains Wetlands. These wetlands which have the potential to be affect by Mimosa pigra provide habitat for the following nationally threaten species; the Greenshank (Tringa nebularia), Little curlew (Numenius borealis), Northern Curlew (Numenius minutus), False Water Rat (Xeromys myoides), Great egret (Egretta alba), Glossy Ibis (Plegadis falcinellus), Marsh Sandpiper (Tringa stagnatilis), Curlew Sandpiper (Calidris ferruginea) and Cattle egret (Ardeola ibis).
The Mimosa Pigra Plant
- Flowers are light pink, round and fluffy balls generally 1-2 cm across.
- Each leaf is approximately 25cm long and has up to 16 opposite segments, which consists of segments 5cm long made up of opposite pairs of leaflets. These leaflets fold up when touched or at night.
- The thorns of Mimosa pigra resemble those found on a rose bush however on Mimosa pigra these thorns are much more numerous.
- The seeds are oblong approximately 4-5 mm by 2 mm in size encased in a brown hairy segmented pod 6-8 cm in length.
- Mimosa pigra seeds have an average seed life of 22 years.
- Mackay Regional Pest Management Group 2013, Weeds of the Mackay Whitsunday Region
- The State of Queensland, Department of Agriculture and Fisheries, Mimosa pigra, Fact sheet
- SunWater Limited, Dams Owned and/or designed by SunWater
- Drewry. J, Higham W, Mitchell. C 2008, Water Quality Improvement Plan: Final report for Mackay Whitsunday region, Mackay Whitsunday Natural Resource Management Group
- The State of Queensland, Department of Environment and Resource Management 2011, REED Regional Ecosystem Description Database