Port Jackson (Acacia saligna): Recognising the Port Jackson Willow
  • Port Jackson is a common evergreen shrub or small tree.
  • It grows in fynbos, near streams and wetlands and on the coastal plain where there is a high water table.
  • It has long, slender phyllodes that look like leaves. These long phyllodes make the plant look like a willow tree although it is actually an acacia tree.
  • The Port Jackson Willow produces bunches of bright yellow flowers like small pom-poms from Spring to early Summer.
  • The slim, straight pods are brown with a pale edge, and slightly constricted between the seeds. They fall off the plant after releasing the shiny dark brown seeds.

 

 

 

 

 

 

 

Port Jackson (Acacia saligna): From introduction to invasion:
  • Port Jackson Willow was introduced from Australia to stabilize sand dunes, to provide fodder for livestock, and because its bark was used in the process of tanning leather.
  • Plantations became a source of seeds, and Port Jackson quickly invaded river valleys and coastal areas.
  • It produces huge numbers of seeds, which are spread by rivers and buried by indigenous South African ants. They lie dormant in soil and germinate after a fire.
  • Australian acacia trees like Port Jackson are able to grow well in poor soil because they have symbiotic bacteria in their roots that take Nitrogen gas from the air between the soil particles and turn it into fertilizer for the plant! This process is called Nitrogen fixing.

 

 

 

 

 

Port Jackson (Acacia saligna): Controlling Port Jackson
 
Gall Rust fungus
  • A Port Jackson tree can resprout from the stump if you cut it down, so if you want to kill the tree you have to paint the cut stump with herbicide
  • A gall rust fungus (Uromycladium tepperianum) was first released into South Africa from Australia in 1987 as the biological control agent. The spores are dispersed by wind and rain. The fungus infects the plant, producing irregular brown swellings called galls. It takes food from the cells, which weakens the tree and makes it more likely to die from other factors like drought. It also reduces the number of seeds that are produced.
  • It is best to use a combination of all three methods of alien plant control to eradicate this serious invader.
  • In South Africa you need special permission to grow Port Jackson. Otherwise you must remove it from your property.

 

 

 

 

 

Port Jackson (Acacia saligna)
Terrestrial plants:      Aquatic plants Terrestrial animals: Aquatic animals
Kikuyu Grass Water Hyacinth Argentine Ant Largemouth Black Bass
Port Jackson Willow Parrot's Feather European Starling Common Carp
Rooikrans Spanish Reed Feral Cat European Mallard