Left Image: Black locust (Robinia pseudoacacia) - Poisonous to humans and animals, this tree spreads quickly and forms dense thickets that physically and chemically force out native plants.

Right Image: Black tea-tree (Melaleuca bracteata) - Native to the whole northern half of Australia, black tea-tree is a prized garden species with a huge range of cultivars to suit all tastes and climates.

Left Image: Lilly pilly (Syzygium smithii) - One of Australia's proudest garden exports, the beautiful lilly pilly comes in a rainbow of cultivars and can tolerate most conditions well - including fire!

Right Image: Broad-leaf privet (Ligustrum lucidum) - Both shrub and tree depending on conditions, the fruit of the broad-leaf privet is poisonous to people. Outcompetes both native species and all kinds of agricultural plants.

Left Image: Cotoneaster (Cotoneaster glaucophyllus) - Pretty but problematic, cotoneaster is found growing in thick clusters of bushes in urban bushland. It's poisonous to livestock, dogs, and mildly so to humans as well.

Right Image: New South Wales Christmas bush [Ceratopetalum gummiferum] - A timely inclusion in the list with less than a month until Christmas, the New South Wales Christmas bush is a garden favourite across the hemisphere thanks to its brilliant red flowers that reach full bloom right on Christmas.

Left Image: Gazania (Gazania rigens) - Gazanias spread far, wide, and easily. The pretty appearance belies a significant environmental pest species, one that outcompetes native plants and pasture species and chemically prevents other plants from growing.

Right Image: Xerochrysum bracteatum (Xerochrysum bracteatum) - One of the most well-known and best-loved of Australia's native paper dasies, the golden everlasting is a beautiful plant that looks great growing in your garden without putting ecosystems and agriculture at risk.

Left Image: Australian blackthorn (Bursaria spinosa) - Another native favourite, especially for your native butterflies, moths, and bees, Australian blackthorn is a great-looking flowering shrub that can bloom year-round.

Right Image: Hawthorn [Crataegus monogyna] - Brought to Australia as a hedging plant, birds have spread hawthorn across Australia where it has become a serious weed of native forests, woodlands, and the banks of creeks and rivers.

Left Image: Scotch broom (Cytisus scoparius) - Once prized as a garden plant due to its bright bunches of yellow flowers, Scotch broom quickly established itself as a major weed that's also toxic to humans and some animals. This thicket-forming shrub is a particular problem in temperate areas like much of the Snowy Monaro.

Right Image: Dagger wattle (Acacia siculiformis) - A less common, but very high-country friendly variety of the beloved wattle family. A little trickier to come by than more common species, dagger wattle makes a great windbreak plant, colder-climate garden shrub, and especially local option for Snowy Monaro pollinators.

Left Image: Blue flax-lily (Dianella caerulea) - Common garden favourite across Australia and around the world. The blue flax-lily is very adaptable and resilient perennial with grassy foliage and blue flowers in the warmer months.

Right Image: Pampas grass (Cortaderia species) - Serious problem in natural areas and forestry plantations, pampas grasses grow in tall tussocks with unqiue fluffy flower heads. A major fire hazard that harbours feral animals, this pest plant is prohibited from sale in many parts of NSW.

Left Image: Royal grevillea (Grevillea victoriae) - A native mountain favourite, the royal grevillea built its reputation on unique red or orange flower clusters and its speading, shrub-like habit. An important food source for natiuve birdlife, including spinebills and honeyeaters.

Right Image: English ivy (Hedera helix) - The bane of many a gardener's existence, ivy is also a common invasive plant species in urban, semi-urban, and natural environments. There are many, many alternatives available that make life easier for you in the garden, and for environments and neighbouring gardens nearby.

Left Image: Flame tree (Brachychiton acerifolius) - Famous for a reason, the flame tree is a deciduous native of the east coast that covers itself in bright red flowers. Cultivated the world over, it's a great choice to plant in place of the many invasive and introduced tree varieties available.

Right Image: Box elder (Acer negundo) - Small in stature but big in its negative environmental impact. The box elder was introduced as a garden ornamental, but rapidly escaped and overran many water-side environments. Also a serious problem for many forest areas and places with disturbed ground.

Left Image: Firethorn (Pyracantha species) - Small and spiny invasive shrubs that outcompete native plants and cause injuries to people and animals.

Right Image: Bottlebrush (Callistemon species) - Better looking and better for the environment, there are few gardens that couldn't be improved by a native bottlebrush tree or two.