As defined by the department’s Weed Management Policy:

Weeds are plants (not necessarily non-native) that grow in sites where they are not wanted, and which have undesirable environmental or economic impacts, or both.

Weeds can reduce biodiversity, or adversely affect the integrity, conservation value and processes of ecosystems. They do this by, among other things:

  • successfully out-competing native species for resources including available nutrients, water, space and sunlight
  • replacing the native plants that animals use for shelter, food and nesting
  • impacting on native plants or animals due to toxins or excluding animals from usual habitats because of thorns or other adverse habit
  • providing habitat for introduced animal pests
  • altering fire regimes, potentially making fires more intense, and possibly altering their seasonality and frequency

Characteristics of invasive weeds

Both introduced and native plants have the potential to become weeds, if they have certain 'invasive' characteristics including:

  • Large volumes of seed
    The production of large volumes of viable seed which may remain dormant in the soil for many years
  • Effective dispersal mechanisms
    The use of spikes, hooks, wings or animal-attracting fruit to aid their dispersal
  • Rapid seedling growth and establishment
    The ability for seedlings to rapidly grow and establish in areas, out-competing other plants
  • Vegetative reproduction or regeneration
    The ability to regenerate or reproduce vegetatively
  • Disturbance invaders
    The ability to invade recently disturbed lands such as road verges and gravel pits
  • Allelopathy
    The ability to release self-protecting toxins that interfere with the growth of surrounding plants