I make a distinction between two groups of non-native species that settle down and reproduce outside their homeland.
The bad guys include Asian hornets, Burmese pythons, Japanese knotweed, chestnut blight, spotted lanternfly, cane toads, kudzu, and giant hogweed … The list that harms our interests and natural ecosystems seems endless. Human traffic is responsible either through deliberate or accidental transfer of aliens. We don’t notice threats until too late to reverse. Most conquerors of natural habitats arrived after 1900, thriving in new worlds where natural controls of foreign population growth are weak and evolve too slowly. They came hidden in commercial cargo, on the soles of hiking boots, and chosen by well-meaning horticulturists, plant collectors, and others who never imagined a downside.
For example, I see miles of roadsides and nature trails bordered by dense Japanese stiltgrass that swamps native plants. Native grazers, ignore the pernicious weed. This is the season when left unmown, it sheds billions of seeds for germinating next year or lying dormant in the soil for years. That is only one of countless challenges to healthy ecosystems and farms. A recent U.N. report estimates a global annual cost of $423 bn.
We are urged to cultivate native plants. It’s sound advice though few garden centers sell them; some species no longer live where they used to thrive because of the changing climate. It’s easy to feel beaten by aliens spreading across land, river, and sea. As an elder now, I sadly remember things were different when I was a kid. But I have made peace with some non-native plants, pretty good guys that bring more benefit than harm to a garden. Without them many native species would not hold on.
After experiments, I found non-native plants to nurture that are attractive to us and to local wildlife welcome here. Each year gets better. Visitors are delighted with clouds of butterflies and the buzzing of contented bees navigating flowers. In late summer a flock of goldfinches rock on seedheads, and if we attract Japanese beetles, insectivorous birds soon follow!
The composite image shows my top five non-native plants: Mexican sunflowers, Blue Fortune sage, White clover, Lantana, and Mountain mint (native to VA but formerly absent in this district). They spread without my help and don’t aggressively displace our beloved natives. But what would they call us if they could? Worse than the worst, the most invasive species in Earth’s history, spreading on every continent to disrupt the evolved balance of nature.