A weed is defined as a plant that has the potential to compete with other plants and replace native vegetation. Like any type of infection, a weed usually grows aggressively and takes over the bush. This transforms the habitat and makes it less suitable for native plants and animals, reducing biodiversity. Weeds also increase the fire risk enormously – just look at the fuel load (tall, dead grass) in the above photograph. Weeds are usually plants from another country, but they can be a native; many West Australian weeds are native plants from eastern Australia. Some of the weeds present in Mardo Reserve are:
Tree Lucerne or Tagasaste
Native to the Canary Islands, this 1-6m shrub is grown widely in Australia as fodder for livestock. It has escaped into bushland throughout the Perth region and smothers native vegetation. It can be removed by treating larger plants with the appropriate herbicide and hand-pulling seedlings.
Flinders Range Wattle
Originating in South Australia, this plant is fast becoming one of the most common weeds in Mundaring. It is planted as a screening or hedge shrub because it is fast growing and has dense foliage, which also makes it take over natives. Each year plants produce large amounts of seed which are eaten and spread by several birds (especially pigeons like the Common Bronzewing). Mature plants should be felled and seedlings can easily be hand-pulled.
Originally from north Africa, this weed does particularly well in disturbed areas, especially where the understory is absent. Once established it creates a thick monoculture, preventing other native plants from recolonising. Stinkwort is best removed by hand, and care should be taken to not spread the very sticky seeds.
There are numerous other species of weed found in Mardo reserve, including Blowfly Grass, Onion Grass, Veldt Grass, Watsonia, Bridal Creeper and Sydney Wattle, although these are not yet common. Ongoing monitoring will ensure weeds do not continue to thrive and threaten the native plants. For more information about weeds, you can contact the Shire of Mundaring.
Below: a creek in the Perth Hills ibeing choked by Watsonia. This
is a big fire hazard!