We live on the continent so distant from other land masses that nature went free-form on a protected canvas, producing platypus and tree kangaroos — on land girt by seadragons. Yet the day I moved to Australia, out the car window were plants in the parklands I knew immediately, because like me those plants were immigrants.

How do plants emigrate? In 1856, Darwin floated seeds in salty bath tubs to test how long they could travel across the sea and still sprout. One day his 8-year-old son Franky wondered: could a dead bird sail the ocean with a full stomach and consequently disperse a crop of seeds? Together, the family fed a pigeon its last meal, and sacrificed it to science. After a month in saltwater, the seeds in the bird’s belly could still grow when planted. Suddenly, the ability of plants to jump continents seemed realistic.

Flora and fauna are instinctively pioneers. Spiders release themselves on silk lines to float to a new spot on the whims of the winds. Plants outsource movement, often hiding their seeds in delicious fruits to entice feasting beasts and eventually get deposited new places in a handy fertilizer packet.

Species move by a mix of accident, instinct and human design. Shortsightedness prompted celebration when foxes were imported to be hunted, or cane toads shipped down under to battle beetles. Homesick landowners around the world constantly colonise landscapes. We install familiar plants for aesthetic pleasure without considering whether a cottage garden favourite might spread shoots that steadily undermine remnant species as an insistent interloper.

Human migrations worldwide brought livestock, trotting on hoofs that transport wedged-in seeds of invasive plants and trample native grasslands, whose roots down under were accustomed to weight being distributed along long thin kangaroo feet.

Underwater, pretty purple Northern Pacific Seastars ferociously outcompete Victorian natives, compliments of visiting ships dumping seastar-filled ballast water thus depositing these mega-breeders to settle in, reproduce by the millions and feast on shellfish.

Weeds. Pests. Invasive species. Out-of-place flora and fauna present particularly tricky ecological challenges in the sensitive and unique ecosystems of Australia.

Back in Chicago, my housemate Gabi had once kneeled in our veggie patch, hesitating. “Who decides what is a weed? Perhaps I shouldn’t pull these.” The other gardeners stifled eye-rolls and wondered who had mismatched the philosopher to the weeding chores.

Most cities are saturated with useful plants we have simply lost the ability to recognise. I later learned many plants we’d spent collective hours pulling up were just as useful as the cultivated crops with which they competed. How had I, avid nature nerd, lived ignorant of the witchy nutritional bounty being laboriously sheared, poisoned, and generally wasted under the banner of ‘weed’ removal?

It felt like a superpower to notice, harvest and celebrate the weeds of Chicago, mostly long-ago arrivals that thrived in disturbed soils of urban landscapes. Maybe Gabi was right: why be so judgy about enthusiastic plants from far away?

Then, like Pistol and Boo, I got to Australia and was schooled on how serious species transport is taken down under.

Full biosecurity response swept into force early this year when a single Brown Marmorated Stink Bug was spotted in a shipment of terracotta pots from Italy. Fearing their all-you-can-eat appetite for crops, Agriculture Victoria deploys a 12-week trapping and surveillance program in a radius surrounding any sighting of this potential economic terrorist.

Stinkbugs are already populous Stateside. I recall my father muttering dad-swears while vacuuming hordes of stink bugs off Virginia windows before guests arrived. We might combat bugs in one breath, yet plant an exotic garden without pondering whether the selected species suited (or spoiled) the local ecological balance.

In defense of our domiciliary ignorance, holistic perspective has dwindled for generations. Plant and animal literacy is slow, old-fashioned learning from walking your country. The 1950s intensified our modern easy-fix mindset, assuming actions like planting kudzu for erosion control Stateside and military camouflage in Fiji is a clever drag-and-drop solution with no contextual side effects.

Alas, Kudzu vines grow up to 30cm per day, zapping soil of carbon-storage capabilities. They now smother 3 million hectares of the southern United States like a green Cousin It. New Zealand tactfully declared kudzu an ‘unwanted organism.’

Parsing the world piecemeal risks naïve and hazardous environmental impacts. The ultimate outfall, climate change, has prompted a much wider audience to debate ecological balance. Species from polar bears to mosquitos are now shifting their natural ranges to seek comfortable survival zones.

Should an introduced species eventually belong? Species certainly naturalise, reproducing without manual cultivation. (Overenthusiastic subsets become a nuisance or invasive.) Many become signature residents, like city pigeons whose cliff-dweller heritage suits life amongst skyscrapers, or railway corridor fennel foraged by nanas.

Over earth’s history, every single species has migrated. It is easy to believe, looking within one’s lifetime, that the lines are fixed about where things should naturally occur. It is easy to leap to hardline conservationism. Survival of the fittest loses all appeal as we watch extinctions add up.

Nevertheless, nature is ever-changing, and ‘belonging’ is mutable. As with many ecological challenges, the issue may be the pace at which modern living triggers changes, without a sense of which strings we’re tugging in the web of life as a consequence. The only way to solve that is to pay attention, becoming as curious as Darwin’s 8-year-old and as rapidly adaptive as a weed.