Volunteers are being sought by the Department of Water to help eradicate a weed that is threatening sensitive Pilbara river systems and significant Aboriginal sites.
The introduced weed - Parkinsonia aculeata - known locally as Parki - has been named as a Weed of National Significance because of its potential impact on sensitive ecosystems and cultural sites.
It was introduced to Australia some time prior to 1900 from parts of North and South America and was used as ornamental shade and to form hedges.
The department's Pilbara regional manager Hamid Mohsenzadeh said Parki generally inhabits river zones and areas that are subject to flooding in the semi-arid to sub-humid tropical areas of Australia.
"This serious weed has invaded the Fortescue River and has impacted on tourism, cultural values, pastoral activities and the river ecosystem," Mr Mohsenzadeh said.
"Our department has been working hard for many years to control infestations of this invasive and destructive weed.
"Our officers have carried out weed control activities since 2001, in partnership with the Department of Environment and Conservation (DEC) which has been actively managing Parki and other weeds on adjoining land in Millstream National Park.
"These activities have also been supported in the past by Green Corps and Conservation Volunteers Australia.
"Infected areas at Gregory Gorge are treated by chemical application. The bases of plants are sprayed or trees are cut down and the stumps are sprayed.
"The department continues to tackle this weed with help from enthusiastic volunteers from DEC, the Water Corporation, State Emergency Services, the Ngurrawaana Community and interested local residents.
"However, we would welcome more support from other volunteers for these trips that usually take place from May to November."
Mr Mohsenzadeh said Parki is a thorny, many branched shrub or small tree reaching up to eight metres high. The flattened leaves are ten to 50 centimetres long, and have two rows of tiny oblong leaflets along their length. Distinctively, the main trunk is bright green allowing the plant to photosynthesise even when completely defoliated through drought or grazing.
Parki flowers opportunistically throughout the year to exploit favourable seasonal conditions. The flowers are predominantly yellow, but one petal can have either orange spots or is completely orange.
Anyone interested in volunteering on a Parki trip in 2009 should contact the Department of Water Pilbara Region on (08) 9144 2000.
Media contact: Dianne Dixon (08) 6364 6983 / 0419 910 847