EPPO Global Database

EPPO Reporting Service no. 11 - 2007 Num. article: 2007/225

Weeds of the future: garden plants which may threaten grasslands in Australia

Introduced plants in Australia can be categorized into three major groups:
  • Widespread invasive plants: these naturalized plants are causing significant economic, environmental and social costs
  • Emerging and sleeper invasive plants: these naturalized plants are spreading or are likely to spread
  • Future weeds: these plants are not yet naturalized.

While most work and research focuses on the 2 first categories, a study has been undertaken to identify garden plants which could in the future become a threat to grasslands in Australia.
This study was based on the Western Australia Department of Agriculture and Food’s “plant database” which covers approximately 576 000 taxa.

First of all, this database was queried so that the species meet the following criteria:
  • They are already introduced into Australia
  • They are not naturalized nor reported as weeds in Australia
  • They are recorded overseas as environmental and/or agricultural weeds.
This resulted in an initial list of 1080 species. In order to focus on the plant species presenting the greatest threat to the Australian grasslands, the following types of plant species were then removed:
  • cold climate tree species
  • species recorded as occurring in aquatic environments (except for Poaceae and Cyperaceae species)
  • species with a single reference as a weed species outside of Australia
  • species referenced as a weed overseas in climates dissimilar to Australia
  • species with none or a single record of being sold in Australia
281 species were finally identified as presenting the greatest potential threat to the grasslands of Australia.

Case studies were undertaken and provided detailed descriptions and potential distributions in Australia for the following 11 species: Asclepias syriaca (Asclepiadaceae) originating from North America; Equisetum spp. native to the northern hemisphere; Festuca gaulthieri (Poaceae) originating from France and Spain; Hieracium spp. (Asteraceae) originating from Europe and Asia; Inula helenium (Asteraceae) native to Eurasia; Lonicera spp. (Caprifoliaceae) originating from Asia, Europe and North America; Miscanthus floridulus (Poaceae, originating from Japan, Taiwan and the Pacific Islands); Nassella tenuissima (Poaceae) originating from South America; Onopordum nervosum (Asteraceae) native to the northern hemisphere; Ornithogalum nutans (Liliaceae) native to south-eastern Europe; and Tamarix gallica (Tamaricaceae) native to southern Europe, Asia and Africa.


Barker J, Randall R, Grice T (2006) Weeds of the future? Threats to Australia’s grazing industries by garden plants. Meat and livestock Australia limited, North Sydney, Australia, 107 p.