1636 Weeds CRC_IFIA book_web_v2.qxd - Department of ...

Background
6
Some plants become problems
Only a small percentage of the many thousands of plant species introduced into Australia have successfully naturalised
here. Of the 26,242 introduced plant species in Australia 2,739 have naturalised, leaving 23,503 species grown and
cultivated now or earlier. Can these therefore be considered as valuable assets in our horticultural industries?
Unfortunately, not all of these 23,503 plant species are without risk as many are well known weeds in other countries.
There are 5,907 species present in Australia which have weed histories elsewhere in the world but no current history
as a weed in Australia. It is these plants that are most likely to become weeds in Australia, given the right opportunities.
The safest option is simply never to use these species in breeding programs, domestic garden plantings or landscaping
projects. Restricted uses such as cultivation purely in greenhouses or air conditioned glasshouses in areas well outside
their normal climate ranges could still be considered, unless the end purpose is for propagation and distribution
into suitable climate regions.
Australia has a vast range of climate types and no matter how well intentioned a gardener or nursery may be those
potentially weedy plants could well outlive their carers, and who is to say that the next owner will take such care or
indeed even understand the risks of such species.
Even without these weedy species there is still a species pallet of just over 20,000 taxa to utilise for all horticultural
purposes. This is in addition to the 11,000 cultivated Australian natives, introductions of additional new Australian
natives to horticulture and new species introductions from outside Australia, screened for their weed potential by
Biosecurity Australia before entry. With access to over 30,000 species of plants it is difficult to see any basis for
complaints that people are being restricted in the range of plants available for use.
CRC for Australian Weed Management The introduced flora of Australia and its weed status