The “Weedy” West, Past, Present and Future

The Perth Branch this month welcomes Greg Keighery, one of WA’s living botanical treasures, to present on WA weeds.

Weeds are a highly dynamic component of Western Australia’s plants. Weeds can be growing in gardens, establishing populations outside the fence, failing to establish themselves, or becoming widespread and beyond eradication.

The introduction of many thousands of non-native plant species into Australia for agriculture, horticulture and gardening has occurred since European settlement. Urbanisation (especially gardens) and water points for grazing animals created the foci, then altered land and widespread disturbance allowed weeds to be established and spread. Currently, it is estimated that around 26,000 exotic plant species are cultivated in Australia, rising each year, close to equalling the native flora. These garden species were and are the source of most of our existing and probably future weeds, about 2,800 cultivated species have become naturalised in Australia.

Most accounts of weeds in Australia focus on the financial cost to agriculture in a broad sense. With increasing environmental awareness, invasive species (algae, fungi, plants and animals) are now recognised as a significant threat to our unique biodiversity, an irreplaceable core asset. The vascular plant components of these invasive species in natural areas are now usually grouped as environmental weeds.

While invasive animals are often the focus, weeds pose the greatest threat to remnant bushland. The talk will address issues about what is a weed, can any plant be a weed? How we rank weeds, since there are so many (about 1340 in Western Australia) to understand what are the major environmental weeds. Future issues include new technologies that challenge biosecurity methods keeping new weeds out of Western Australia. Increased surveillence is being enacted and new Australia wide co-ordination attempts on major weeds are underway. Climate change will affect weeds and attempts to relocate native species is creating a new class of weeds.

Doors at the Community Centre open at 7:45 pm for an 8:00 pm start, with a $3 donation giving entry to the night’s door prize.