Nursery and garden industry of Australia: garden escapees that are serious environmental weeds
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Thirteenth Australian Weeds Conference
Nursery and garden industry of Australia: garden escapees that are
serious environmental weeds
Hazel E. Dempster
9 Wiria Court, Wanneroo 6065, Western Australia, Australia
Summary Plants from horticulture have been high- trade routes, the rate of development, settlement and
lighted as the major source of both agricultural and the needs of the settlers.
environmental weeds in Australia. The Nursery and ‘European gardens were established in the first
Garden Industry of Australia (NGIA) has taken initia- settlements initially to provide fruits, grains and veg-
tives to define their role and responsibilities. ‘Garden etables but as new European settlers arrived and set up
Plants Under the Spotlight (GPUS), an Australian their ornamental gardens to create their English land-
strategy for invasive garden plants’ (February 1999), scape there began an array of new introduced plants
initiated the program of education to industry members for their estate gardens, hedges and exotic pastures.
and the Australian gardening public, to be aware of This, combined with the gradual disturbance of land
their own roles and responsibilities to follow for the for grazing animals and removal of timber trees in
prevention of further introductions. the early 1800s, destroying the understorey therefore
habitats and sanctuary for fauna, provided a window
INTRODUCTION of opportunity to infiltrate the compromised native
‘Why is the Australian flora so special? Does it matter communities. English holly (Ilex aquifolia L. Aquifo-
whether a plant is a newcomer to Australia, or has been liaceae), mirror bush (Coprosma repens Rubiaceae),
evolving here in isolation for the last 50 million years?’ genista (Genista hispanica Papilionaceae), pittospo-
‘Yes it does. It matters because these new plants are rum (Pittosporum undulatum Vent. Pittosporaceae),
radically changing the Australian environment – for- polygala (Polygala myrtifolia L. Polygalaceae), arum
ever. They are displacing native species, altering not lily (Zantedeschia aethiopica (L.) Spreng. Araceae)
only the diversity and interactions of the flora, but also and watsonia (Watsonia meriana (L.) Mill. Iridaceae)
its value for fauna.’ (Hussey et al. 1997) provided the seed and/or propagule source for the
Why does the NGIA have to show concern for future weeds infestations of today.’ (Watson 2002).
weeds affecting the environment and agriculture? The ‘At the same time these large estate gardens formed,
Nairn Report (Groves 1996) states that ‘in the last 25 small cottage type gardens flourished in nearby coun-
years, 65% of today’s weeds were introduced for use try villages and since villagers could not afford the
in horticulture’. expensive fashionable plants, their gardens proudly
What role has the industry played in this invasion? displayed a floral spread of persistent herbaceous annu-
The responsibility of such weeds has been laid squarely als and perennials. Verbascum (Verbascum dumulosum
at the feet of the industry. Though the industry itself Scrophulariaceae), ivy (Hedera helix L. Araliaceae),
cannot take full blame for this figure, the practice of Nile lily (Agapanthus africanus syn. praecox Willd.
gardening can. Alliaceae), pink and yellow wood sorrel (Oxalis cor-
When did this invasion all start? What events set niculata L. Oxalidaceae)’ (Wilson 2002).
the scene for this more recent invasion? An article Plants were actively traded and swapped across
entitled ‘Tasmanian’s weed flora – Its early origins’ the countryside by travelling villagers enabling a rapid
(Watson 2002) provides an interesting picture of the spread into previously unaffected indigenous vegeta-
sequence of weed invasion into Tasmania starting with tion communities. Others became a serious agricultural
Captain Cook’s voyage on 1773 prior to leaving Bruny weed imposing substantial economic impacts on many
Island, Adventure Bay by planting fruit tree seeds be- generations and many herbs used in estate and cottage
fore he left. ‘This planting and seed sowing activity gardens from this era came to persist as difficult to
heralded the future indiscriminate introduction of an control agricultural weeds.
exotic flora, which of course flourished in a disease ‘The diaries of the Rev. Robert Knopwood, the
free, and lack of natural predators eventually became first chaplain of Hobart provide a detailed account of
today’s common invasive weeds.’ (Watson 2002) early horticultural activities 1804–1835. The diaries
This picture and timing of introduction to Tas- also acknowledge his enthusiasm for collecting seeds
mania would have been similar in most of the earlier and cuttings from all available sources including fresh
settlements in throughout Australia, due to the same offerings from trading vessels in the port of Hobart.
27Thirteenth Australian Weeds Conference
New settlers would frequently collect plant specimens damage their activities were inflicting on our environ-
from various foreign ports of call especially South ment in these disturbed areas.
Africa on their journey to this new colony. Newtown The naturalisation of many of these plants was
Plant Nursery was referred to in 1815 as one of the initially seen as a novelty or accomplishment rather
earliest plant selling establishments. Plants such as wil- than the threat it was to become. The practices of
lows (Salix spp., Salicaceae), poplars (Populus alba L. dumping of garden refuse across the road into the
Salicaceae), English hawthorn (Crataegus monogyna nearby bushland or even worse, further afield whilst
Jacq. Rosaceae), black locust (Robina pseudoacacia on a Sunday drive was common place. The picking
L. Papilionaceae), genista (Genista hispanica L. Papil- of a bunch of naturalised freesias (Freesia alba ×
ionaceae), English and Scotch gorse (Ulex europaeus leichtlinii Iridaceae) to take home for Mum or family
L. Papilionaceae), boxthorn (Lycium ferocissimum excursions to pick blackberries from the local creek
Solanaceae) and cotoneaster (Cotoneaster pannosus or rubbish dump, to make jam, became common place
Franch. Rosaceae) would have been freely available at family activities.
this very early nursery. Weeds galore for the colonist Changing fashions have always been a part of the
to spread far and wide!’ (Wilson 2002). gardening and horticulture scenes. Nursery businesses
‘The introduction of many new exotic species can wanting to expand their production searched for new
be attributed to the enthusiasm of amateur botanists exotic plants to add to their growing lists. The already
such as Robert Lawrence. Importation and exchange established plants which were either considered too
of plant material with European horticulture and bo- common because of their appearance as naturalised
tanical institutes such as Kew Garden for the local weeds, were cast aside, or the fashion trends changed
flora, was of great interest at that time. The Wardian to suit the changing architecture of buildings. The rub-
case to transport plants across oceans becoming more bish dumps of the day became a haven for such cast
reliable by the 1830. Local trade catalogues, botanical offs and their spread into the surrounding bushland
gardens lists and order books provide a comprehen- was rapid.
sive record of the weed flora that was brought into Further introductions such as lantana (Lantana
the State. The 1850s saw new introductions of pam- camara L. var. camara Verbenaceae) and Australian
pas grass (Cortaderia selloana Schult. & Schult.f. natives being transported across borders began to
Poaceae), cotoneaster (Cotoneaster glaucophyllus naturalise, Victorian tea tree (Leptospermum laeviga-
Rosaceae), Paterson’s curse (Echium plantagineum tum (Gaertn.) F.Muell. Myrtaceae) used for an early
L. Boraginaceae), nasturtium (Tropaeolum majus hedging era, the spread of numerous wattle species
L. Tropaeolaceae), Japanese honeysuckle (Lonicera including golden wattle (Acacia baileyana F.Muell.
japonica Thunb. Caprifoliaceae), wandering Jew (Tra- Mimosaceae) out competing local species, into many
descantia fluminensis Commelinaceae) and banana states, are common examples.
passionfruit (Passiflora mollissima Passifloraceae). The environmental impact of the naturalisation
Blackberry (Rubus ulmifolius Schott. Rosaceae) ar- of exotic garden plants became evident. ‘The Nairn
rived in 1843. Boneseed (Chrysanthemoides monilifera Report’ (Groves 1996) reported that 290 exotic spe-
(L.) Norl. Asteraceae) was used for shrub borders in cies of plants had become naturalised in Australia over
estate gardens’ (Wilson 2002). These early introduc- a 25 year period from 1971 with 65% attributed to
tions set the scene for a large percentage of Australian ornamental plants for horticulture. The numbers
weeds incursions and most if not now all have major showed increasing rate of naturalisation during that
eradication or management programs in place through period.
out the southern regions of Australia. Today, new exotic ‘Australian Garden Thugs Facts and Figures’
plant material sought by genuine plant collectors can (Blood and Randall 1998) gives statistics that ‘over
expect to go through a rigorous legal selection and 700 plants grown deliberately in gardens or sold in
assessment process. the trade in Australia have become weeds, of these,
almost 50 are still lurking in gardens. Thirty of these
PROGRESS OF TRENDS are what weed people call ‘sleepers’ (they have the
With the growing and expanding population these known potential to escape) while another 16 are al-
trends continued throughout the twentieth century. ready weedy overseas.’
Australian gardeners continued to seek new plants.
Land disturbance and soil degradation continued. The STRATEGIES
generosity of gardeners ensured that the plants would NGIA and its associated horticultural media follow
spread through family and friends gardens. Nurseries and create fashion for Australia’s parks and gardens.
and gardeners alike were oblivious to the looming The last twenty years has seen many new introductions
28Thirteenth Australian Weeds Conference
to the industry from overseas, as well as plant breed- public about invasive garden plants though gov-
ing and selection within Australia. During this time ernment agencies, the plant industry and the hor-
the Australian environment had continued to change ticultural media.
by degradation, threatening salinity and climatic • To educate the plant industry and horticultural
changes providing an ideal platform to launch further media about invasive plans.
new weeds and the further spread of those already • To obtain cooperation from industry and media in
naturalised. the promotion, sale and distribution of environ-
What has the industry and the associated landscap- mental friendly alternative plants.
ing industry been doing to in its role as horticultural • To increase sales of non invasive garden plants.
promoter to the public of Australia and to prevent the Community education and awareness program
number of naturalised weeds increasing? The National • Focus on the invasive garden plants.
Weeds Strategy (NWS) (1997) sets out a goals and • Equip the community toolbox.
objectives for a strategic approach to weed problems of • Promote the role of the industry and govern-
national significance. The Cooperative Research Cen- ment.
tre for Weeds Management Systems (Weeds CRC) is • Ensure staff are trained and skilled in providing
a national initiative to support, assist or drive industry community education.
decisions and plant selections. Biosecurity Australia Target groups
(BA) regulates the importation of new plant material • Horticultural media.
through the Australian Quarantine Inspection Services • Nurseries, garden centres and landscapes.
(AQIS) weed risk assessment protocol. • Local government.
NGIA’s publication The Nursery Papers Issue No. • Botanic gardens and genetic resource centres.
1998#10 titled ‘Preventing the introduction of potential
weeds as ornamental plants to the Industry’ advises GARDEN THUGS LIST
that ‘AQIS carries out assessments of weed potential From an original 860 species originally identified as
on all new plant imports.’ New ornamental plants in Garden Thugs, a list of 100 was presented of the In-
particular are assessed as they are the major source dustry for comment. The list indicated any legislation
of plants that, in time, may become naturalised weeds control and as well as the state and territories where the
that impact on our environments. Weeds ranking and plant has become invasive in natural ecosystems.
assessment systems are in place for assessment of the The final list of 52 plants was identified by the
potential of plants including those from horticulture GPUS strategy as ones to be discouraged from use in
to become invasive and allow the appropriate man- Australians gardens. This list was published in NGIA
agement programs to be implemented. Plant Breeders publications The Nursery Papers (Issue No. 2000/12)
Rights (PBR) has legally enforceable legislation and titled ‘Invasive plants not wanted in public or private
makes it the PBR owner’s responsibility to be aware gardens identified’. A further Issue of The Nursery
of such restrictions as noxious or invasive weeds when Papers (Issue No. 2001/14) ‘The facts on hazardous
making submission for new plants. NGIA responsi- plants’, lists plants many of the escaped exotics which
bility to the NWS is seen as coordination, policy, re- are proclaimed weeds
search, monitoring, education, advocacy and energetic Considerable concern was express that for at least
weed control. the next few decades many new weeds or ‘sleeper’
weeds will continue to emerge from plants already
INDUSTRY RESPONSE present on Australian gardens and nurseries. Newer
‘Garden Plants under the Spotlight: An Austral- introductions such as white butterflies (Gaura lindhei-
ian strategy for invasive garden plants’ (Blood and meri Engelm. & A.Gray Onagraceae), African daisy
Randall 1998), was a project of cooperation with the (Osteospermum ecklonis (DC.) Norl. Asteraceae), di-
Weeds CRC and the then Nursery Industry Association etes (Moraea vegeta L. Iridaceae) have been already
of Australia (NIAA) and state, territory and federal noted as naturalising by Bushcare groups involved in
regulatory agencies. The following initiatives were weed removal from bush reserves.
put in place: The focus would be on informing the gardening
Strategy list public, commercial users and members of the nurs-
• To maintain the profitability of the industry dur- ery and garden industries of the need to ensure plants
ing a time of increasing local council, state and are not used in either public or private gardens. The
territory government regulatory concerns over Weeds CRC programs ‘Garden Thugs’, and ‘Weed
weeds. Buster Week’ are conducted nationally for the nursery
• To educate and inform the Australian gardening industry and public education.
29Thirteenth Australian Weeds Conference
INDUSTRY AIMS role in keeping to create awareness of this issue and
In 2000, GPUS conducted a survey by the Weeds at the same time encourage the purchase and planting
CRC and Agriculture Western Australia to determine of non-invasive species.
nursery customers’ attitudes to the sale of weedy gar- In November 2001 the ‘Flora for Fauna’ campaign
den plants. The result showed that an overwhelming was launched (Moody 2001). This is a national ini-
majority of nursery customers do not want to buy and tiative by the Nursery and Garden Industry. With the
grow invasive plants in their gardens and put trust in support of funding from a Natural Heritage Trust grant,
their local nursery for the correct advise and not to ‘Flora for Fauna’ looks at the ways that the gardening
have them for sale. community can be encouraged to grow suitable plants
Fashion demands from the gardening public meant preferably Australian native plants local to each areas
that relatively new and untested species of plants were into home gardens to attract local flora and fauna.
being distributed. Computer software has been now These gardens will become protected habitats whilst
developed to be able to make projections of a plants bringing many fairly sterile gardens to life. This in
propensity to become invasive and allow precautions turn would provide further corridors for the fauna to
to be taken. Any new introductions would be subject interact with the flora between local bushland parks
to this scrutiny and existing garden plants showing and reserves.
weediness can be assessed. A good example of this is Though not directly aimed at probable weed spe-
lantana (Lantana camera L. Verbenaceae) which is a cies, lists presented for the project have provoked much
well known environmental Weed of National Signifi- comment particularly from environmental groups Aus-
cance (WONS) in some states, has been projected to tralia wide who know their areas and are well aware
become invasive in Western Australia from Geraldton of the garden escapes with which they deal with in
to Esperance and there is already evidence of naturalis- their environmental management program. This has
ing in these areas (Walton 2000). resulted with much consultation by these groups with
The trend to create water features in gardens has industry and to encourage local nurseries to be more
given the rise in reports of prohibited water plants such familiar with the management problems which could
as salvinia (Salvinia molesta D.S.Mitch. Salviniaceae), occur. This program has lead to the introduction of
water hyacinth (Eichhornia crassipes (Mart.) Solms further plant species into the industry especially on
Pontederiaceae) and arum lily (Zantedeschia aethi- the local scene.
opica (L.) Areaceae). Prompted by the GPUS programs, industry ex-
The challenge is to work with this information and ecutives in all states and territories have acted and
follow protocols put in place for removal from sale initiated educational programs with their members
and safe substitution. In a further issue of The Nursery and the public. In the Australian Capital Territory
Papers (Issue No. 2001/12) titles ‘Discovering alterna- and the Northern Territory, nurseries working with
tives to garden escapes’ and states that ‘the issues of local community groups have all agreed not to sell
invasive plants, often referred to as ‘weeds’, is a com- invasive plants that will effect the biodiversity of their
plex one. What the industry should do about this issue local ecosystems.
is equally, or even more, complex.’ It aims to highlight
only the most invasive garden plants still found in the PROGRESS IN WESTERN AUSTRALIA
nursery trade, develop and promote an extensive list Western Australia is a world famous flora hot spot. We
of alternatives and mostly, improve the understanding have over 14,000 native plants species and that figure
of this issue by the gardening community. will increase as new species are still being identified,
The group of invasive garden plants listed and we have 1400 weed species registered as invasive
their alternatives are direct at the NSW/ACT area. The or naturalised about 40 of these have high invasive
complexity of providing such lists is highlighted and qualities and these will also increase. WA is lucky to
the need for industry in other states to work with local be isolated from many infestations by geographical
communities to provide their own lists to protect the location and separation by an arid desert from the rest
biodiversity of the many different ecosystems found of the continent and their weeds, but ongoing vigilance
in regions throughout the country. is paramount.
One of the industry’s objectives is to respond to The Nursery and Garden Industry of Western
community environmental concerns. The main goal Australia (NGIWA) members are aware of the GPUS
is to work out an approach that would help the gar- campaign. The executive has taken the initiative by
dening public not to want invasive garden plants. As having representation on steering committees for
most gardeners trust their nursery person for correct both the ‘Environmental Weeds Strategy for Western
advice the industry can therefore play an important Australia’ for Conservation and Land Management
30Thirteenth Australian Weeds Conference
(CALM) and the State Weed Plan, and are seeking OUTCOMES
representation of the State Weeds Coordinating Coun- • The aims and strategies of the GPUS programs are
cil. They are continuing their participation to provide well known within the industry.
the best guidelines for the industry in line with the • The streamlining of initiative programs such as
requirements of these plans. NGIWA state confer- ‘Flora for Fauna’ is resulting in more appropri-
ence programs have highlighted the weed threats and ate plant selection for the differing regions of the
outlined the responsibilities members have to partici- country.
pate in the industry’s programs. The annual Garden • Nurseries are changing lines of stock continuously.
Week has been the public arena for public awareness This education program encourages that process to
campaigns. continue and provides guidance as to which stock
West Australian gardeners are inclined to follow lines to avoid with suitable alternatives.
trends set by horticulture media programs and publica- • Building lead-in times to the program will ensure
tions emanating from the more populous states in the that plant replacement occurs on a level playing
east therefore many unsuitable exotic plants have been field for all nurseries and allows stock lines to
introduced over many years with their weed invasive change in time for publicity to gardeners.
unknown in our different climate. The massive hous- • Members are better informed to take responsibility,
ing development in the last 20 years has also seen a to be aware of plant invasive qualities, to remain
similar increase in the introduction of exotic species informed of industry recommendations.
to horticulture. Many of these are now ‘sleeper’ weeds • More exposure of invasive weeds through the
with some already giving indications of spread. horticultural media is enabling the general public
Unfortunately at the moment the Industry in WA to be more informed.
is being severely affected by low rainfall necessitating
severe water restrictions and the outlook for consistent CONCLUSION
rainfall is limited on projections of climate change. The resistance to, or fear of loss of livelihood by the
This is causing severe hardships for many horticultural removal of particular plants species by some sections
enterprises. The use of the more suitable local plants of the industry is still evident and there are those who
has been in decline since the last long dry spell in the feel their rights are being infringed by the programs
1970s with the trend to exotics requiring a high water when it comes to what they can grow.
use and unsuitable for prolonged dry seasons. Despite this ‘the positive benefits gained by the
Many nurseries throughout the state are now com- NIGA in taking the lead on this issue and not waiting to
ing under pressure from state and local government have change imposed upon it are great. The credibility
agencies, as well as, the general gardening public of the industry will be improved through positive pub-
and community conservation groups. Plant lists are licity showing their environmental responsibility and
encouraged to be more in line with the environmental sustainability. The industry, by driving this process,
needs to conserve water and protect the biodiversity will be in a position to control the timing and phase ins,
of the state’s ecosystems from further weed invasion. have a greater input to training and maximise public-
Working and cooperating with local environ- ity opportunities. It is good for business.’ (Blood and
mental groups, many of whom are their customers to Randall 1998).
provide plants of local provenance is a major public There is ample evidence that there will be more
relations exercise in the offing for many nurseries to that enough plants to replace any potential invasive
gain benefit. Many voluntary hours have been spent species into the country’s gardens and satisfy the
pulling out weeds which have naturalised from plants enthusiasts. Plant breeding of both Australian native
which the nursery may have previously sold. National plants and the selection of suitable non-invasive exot-
award winning Western Australian nursery, Zanthor- ics for use in Australian gardens is only in its infancy
rhoea Nursery with community consultation has a local in Australia.
weeds strategy and substitute plant supply. The challenge of this millennium for NGIA is to
The current trend to recommend drought toler- provide non-invasive plants, which do not threaten
ant plants from other countries has inherent dangers the country’s biodiversity. The initiatives of Austral-
as many have evolved and able to multiply in such ian horticulturists and scientists will prevail to ensure
adverse conditions. Weed assessments will determine that horticulture industry is not threatened, and able
their invasive potential. to provide a sound future for its members.
31Thirteenth Australian Weeds Conference
ACKNOWLEDGMENTS ‘Environmental Weeds Strategy for Western Aus-
Nursery and Garden Industry of Australia (NGIA) tralia’. (Conservation and Land Management,
www.ngia.com.au and the Cooperative Research Cen- Como, WA).
tre for Weeds Management Systems (Weeds CRC). Groves, R.H. (1996). In Nairn, M.E., Allen, P.G.,
Thanks to Mr. Phil Watson from the Australian Inglis, A.R. and Tanner, C. ‘Australian Quaratine
Plants Society, Tasmania Region for the use of infor- – a shared responsibility’. (Department of Primary
mation from his article ‘Tasmania’s weed flora-its early Industries and Energy, Canberra).
origins’ (Eucryphia, March 2002). Hussey, B.M.J., Keighery, G.J., Cousens, R.D., Dodd, J.
and Lloyd, S.G. (1997). ‘Western weeds, a guide to
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2001/14. (Horticulture Australia, Nursery Industry natives to garden escapes. The Nursery Papers Is-
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Atkinson, I. (2000). Invasive plants not wanted in State Weed Plan Steering Committee (2001). A Weed
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Papers Issue No. 2000/12. (Horticulture Australia, culture, Kensington, WA).
Nursery Industry Association of Australia). Watson, P. (2002). Tasmania’s weed flora – its early
Blood, K. and Randall, R. (1998). ‘Australian Garden origins. Eucryphia, March 2002. (Australian
Thugs Fact and Figures’. (Cooperative Research Plants Society, Tasmania Region).
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