English ivy, a common Blue Mountains environmental weed

What is an environmental weed?

Unfortunately, some plant species that have been introduced to the Blue Mountains, either from other regions of Australia or from overseas, have developed into environmental weeds. Why should we be concerned about weedy plant species?

Environmental weeds pose a serious threat to the health and ecological integrity of local bushland, the Blue Mountains National Park and the Blue Mountains World Heritage Area.

Environmental weeds are plant species that have been introduced to the Blue Mountains. They have thrived, spread rapidly and degraded locally indigenous vegetation communities (the local or native vegetation that occurs naturally in the Blue Mountains), such as rainforests, woodlands and swamps. Why does this happen?

Many introduced species often have no local competitors, such as other plant species or herbivores, and become difficult to control. Local environmental conditions may particularly suit certain introduced species, allowing them to thrive e.g. soil, climate. Introduced plant species that reproduce prolifically have potential to develop environmental weed behaviour.

Brown Cuckoo Dove consuming plant seed Lawson - P Ardill 2024

Plant seed can be widely distributed by wind, water, human action and animals, particularly birds. Also, there are plant species, such as bamboo, that spread rapidly via underground stems (rhizomes). Even the broken branches of certain plant species, such as willows, can establish roots and become viable plants if moisture is available.

As they spread, weeds overwhelm and quite often totally displace locally indigenous vegetation communities. For example, introduced vines such as Japanese Honeysuckle and Jasmine can completely smother trees, shrubs, ferns and ground plants. Local vegetation communities may be completely replaced by a weed monoculture comprised of Privet or Blackberry.

Weeds can also adversely impact our local animal species. For example, the dense, ground-layer thickets of stems and leaves created by English ivy, referred to as ivy deserts by ecologists, completely cover all soil and existing plant species. When this occurs, lyrebirds, bandicoots and other animals are unable to engage in their usual ground feeding behaviour.

Honeysuckle and Arum Lily overwhelming ferns - P Ardill 2024

In addition to their detrimental ecological impacts, environmental weeds destroy agricultural and other economic assets. Weeds are expensive to control. Blue Mountains City Council (BMCC), the NSW National Parks and Wildlife Service and other government, non-government and industry entities expend considerable financial resources on the control of environmental weeds.The CSIRO estimates that weeds cost the Australian economy approximately five billion dollars per year. Also, environmental weeds can seriously disrupt the amenity of residents and communities, as happened when Prickly pear infested eastern Australia for many decades.

What can you do to help?

• Please seriously consider removing or controlling any environmental weeds on your property, or as many as possible. Even removal of weed seeds can be environmentally beneficial. To select and identify environmental weeds, see the Identification and control of weeds & Environmental weeds of the Blue Mountains sections below. Place weed seeds in your BMCC green bin. Green waste can be placed in your green bin, or composted.
• Report environmental weeds to Blue Mountains City Council by email at council@bmcc.nsw.gov.au or calling on 47 80 5000.
• Consider planting locally indigenous species on your property i.e. the native plants that occur naturally in your locality. Locally indigenous plant species can be purchased from the Conservation Society Nursery (https://bluemountains.org.au/nursery.shtml), Wildplant Rescue and Native Plant Nursery, Katoomba (https://www.wildplantrescue.org.au/) and Glenbrook Native Plant Reserve and Nursery (https://austplants.com.au/Blue-Mountains-Glenbrook-Reserve).
• When choosing garden plants that are not native to the Blue Mountains, (also referred to as introduced or exotic plants), consult the Australian organisation Gardening Responsibly. This organisation has conducted extensive research into the weed potential of numerous garden plant species. Check the weed potential of your garden plants and any proposed plant purchases at https://www.gardeningresponsibly.org.au/check-your-choice/. The website also offers lots of non-weedy garden species to choose from!
• BMCC implements a Blue Mountains Bushland Nursery Incentive program. Blue Mountains nurseries that do not stock or sell priority environmental weeds are accredited by BMCC. Consider purchasing your garden plants at accredited nurseries. See https://www.bmcc.nsw.gov.au/bushland-nursery for a list of BMCC accredited nurseries.
• Avoid purchasing weed species and packets of weed seed from garden centres, markets or online. Avoid sharing weed species and weed seed with neighbours and friends. Consult BMCC and Bushcare weed management websites and their lists of weed species (see below).
• Before landscaping, purchasing plants or seeds at garden centres, markets, online and at other outlets consult BMCC and Bushcare weed management websites and their lists of weed species (see below).

Garden management suggestions

• Be aware that Australian plant species not indigenous to the Blue Mountains but planted here have turned feral, including West Australian Kangaroo Paw and Bluebell creeper.
• Do not dispose of garden waste, including lawn clippings, near or in bushland. Place all green waste in your BMCC green bin, or compost heap.
• Regularly observe how introduced species are behaving in your garden. Plants that spread rapidly, for example by suckering, or produce numerous seedlings are a concern. Consider removing these plants, especially if they are becoming established in adjacent bushland.
• As discussed, birds particularly consume, transport and deposit plant seed. Many major environmental weeds, such as Holly, Cotoneaster, Ivy and various lilies are distributed in this way. Monitor for unwelcome seedling development in your garden and nearby local bushland.
• Some locally indigenous and introduced plant species can be highly flammable. If you live in a bushfire prone area, consider consulting the NSW Rural Fire Service and its home management advice (https://www.rfs.nsw.gov.au/).
• Consider joining a bushcare group, and help to restore degraded ecosystems. For further information see https://bluemountains.org.au/bushcare.shtml

Blue periwinkle infests pristine bushland - P Ardill 2024

Environmental weeds of the Blue Mountains

Environmental weeds that are often found growing in local gardens, parks and bushland reserves

Check your property for these common weeds: Agapanthus, Arum/Calla lily, Asparagus fern, Bamboo rhizomatous species, Blackberry, Blue periwinkle, Broom species, Butterfly-bush or Buddleia tree, Cassia, Cherry laurel, Cootamundra wattle, Cotoneaster species, Crofton weed, Day lily, English ivy, Evergreen Dogwood, Ginger lily, Gorse, Himalayan honeysuckle, Holly, Jasmine (White), Japanese honeysuckle, Lantana, Madeira vine, Montbretia, Pampas grass, Small-leaved and broad-leaved Privet, Red Hot Poker, Seaside daisy, Spanish heath, Tutsan, Trad/Tradescantia fluminensis, Watsonia, Willow (Grey Sallow).

Removal of these common environmental weeds from your garden/property, or even effective management of their flowers and seeds, could greatly benefit the natural environment of the Blue Mountains, especially if you live near a stream, swamp, bushland reserve or Blue Mountains National Park.

BMCC Blue Mountains noxious and environmental weeds list 2023

Blue Mountains City Council maintains a comprehensive Blue Mountains environmental weed species list. All Blue Mountains environmental weeds are listed. The list was published in BMCC Development Control Plan 2015: Part C Environmental Management, Revision: Amendment 5 (April 2023).

A copy of this list can be found here: BMCC DCP 2015 Weeds List.pdf - please feel free to share it with friends and family.

Butterfly-bush seed is spread far by wind - Meshaal Al Hajali

Often it is difficult to accurately identify and control weedy plant species.

For weed illustrations, management techniques and garden management advice, consult these BMCC resources: Weeds Information Booklet 2024 and https://weedsbluemountains.org.au.

Weeds Australia (https://weeds.org.au) also provides good advice and illustrations.

The Society’s Bushcare Officer may be able to help with plant identification and advice on weed management (https://bluemountains.org.au/office-holders.shtml).

Seek additional advice from Blue Mountains City Council by email at council@bmcc.nsw.gov.au or calling on 47 80 5000.

Professional arborists, bush regenerators and horticulturalists may also be able to offer advice with plant identification and management. They may charge a fee.

Always consult Blue Mountains City Council, professional arborists, bush regenerators and horticulturalists before undertaking tree management works or major landscaping on your property.

Thank you for considering the environmental weed management advice offered by the Society. Please note that Blue Mountains Conservation Society is a volunteer environmental organisation. Members of the Management Committee are volunteers and do not claim to offer professional standard advice. If in doubt about your particular matter of concern, please seek professional advice.

BMCC (n.d.) Weeds of the Blue Mountains Cherishing our bushland Blue Mountains City Council https://weedsbluemountains.org.au/

CSIRO (n.d.) Biological control of weeds https://www.csiro.au/en/research/plants/water-marine/weed-biocontrol

Duursma, D.E., Gallagher, R.V., Roger, E., Hughes, L., Downey, P.O., Leishman, M.R. (2013) Next-Generation Invaders? Hotspots for Naturalised Sleeper Weeds in Australia under Future Climates. PLOS ONE 8:12 DOI: 0.1371/journal.pone.0084222

Environment and Heritage (2024) Weeds Find out how weeds threaten biodiversity and what we are doing about it Department of Environment and Heritage NSW Government https://www2.environment.nsw.gov.au/topics/animals-and-plants/pest-animals-and-weeds/weeds

Gallagher, R., Leishman, M. (2014) Invasive plants and invaded ecosystems in Australia: implications for biodiversity Chapter 6 in Stow, A., Maclean, N., Holwell, G. (eds.) Austral Ark: The State of Wildlife in Australia and New Zealand Cambridge University Press

Groves, R.H., Boden, R., Lonsdale, W.M. (2005) Jumping the Garden Fence: Invasive garden plants in Australia and their environmental and agricultural impacts CSIRO World Wildlife Fund https://wildlife.lowecol.com.au/wp-content/uploads/sites/25/Jumping-The-Garden-Fence.pdf

Hulme, P.E., Brundu, G., Carboni, M., Dehnen-Schmutz, K., Dullinger, S., Early, R., Essl, F., González-Moreno, P., Groom, Q., Kueffer, C., Kühn, I., Maurel, N., Novoa, A., Pergl, J., Pyšek, P., Seebens, H., Tanner, R., Touza, J. van Kleunen, M., Verbrugge, L. (2018) Integrating invasive species policies across ornamental horticulture supply chains to prevent plant invasions Journal Applied Ecology 55:92–98. DOI: 10.1111/1365-2664.12953

Maher, J., Stringham, O.C., Moncayo, S., Wood, L., Lassaline, C.R., Virtue, J., Cassey, P. (2023) Weed wide web: characterising illegal online trade of invasive plants in Australia. NeoBiota 87: 45–72. https://doi.org/10.3897/neobiota.87.104472

Smith, P., Smith, J. (2010) Urban edge effects in the Blue Mountains, New South Wales: implications for design of buffers to protect significant habitats PACIFIC CONSERVATION BIOLOGY 16: 92–100. Surrey Beatty & Sons, Sydney https://bluemountains.org.au/documents/research/blue-mountains-urban-edge-effects.pdf

Strelau, M., Clements, D.R., Benner, J., Prasad R. (2018) The Biology of Canadian Weeds: 157. Hedera helix L. and Hedera hibernica (G. Kirchn.) Bean Canadian Journal of Plant Science 98: 1005–1022 (2018) dx.doi.org/10.1139/cjps-2018-0009