According to the website of the Southeastern Regional Taxonomic Center:
Non-native species, also referred to as non-indigenous species, are those that inhabit a particular ecosystem or geographic region, but do not occur naturally.
If the impacts caused by a non-indigenous species result in ecological damage, economic harm, or a threat to human health, we consider the introduced species to be invasive.
The federal government and all state governments have lists of invasive plants, noxious plants, and exotic plants. Also they all have lists of invasive species. The human species is not on any of these lists.
Scientific Name: Homo sapiens.
Common Name: Humans.
Type: Primates of the family Hominidae; the only surviving species of the genus Homo (all others having become extinct.)
North American Origin: various theories – self introduced via land bridge from Asia; Egyptian or Phoenician via aquatic float; in Florida most recently by the Spanish in search of the Fountain of Youth.
Extent: widespread, congregates socially.
Damage: aggressive; interferes with environmental and economic systems; includes self destructive behaviors.
Control Measures: unknown.
What is the difference between our backyard plants and zebra mussels, fire ants, kudzu, the European starling, or the burmese pythons? It depends on who is writing the lists and whether we have a warm feeling about the species.
In Florida, we have introduced over 900 exotic plant species to beautify developments. They aggressively compete with Florida native plants and change the community for birds, insects, and other native species. Our backyard is a who’s who of the Florida invasive list.
Lantana camara arrived in Florida as an ornamental shrub in 1804. Its success has been at the expense of Florida’s own native species of Lantana (L. depressa). Lantana depressa is now endangered.
The Mexican petunia (Ruellia brittoniana) wants to get out of its bed so badly it throws running shoots five to fifteen inches into the lawn.
The same thing happens with Wedelia trilobata (Creeping oxeye) which flowers nicely and is green most of the year, but wants to take over the lawn.
All on the Florida invasive list.
But hey! The lawn itself is constantly trying to invade most of my beds. Why isn’t the lawn considered exotic and invasive?
Besides the creeping oxeye and the Mexican petunia we have the calico flower (aristolochia littoralisa) growing up our pergola. A vigorous climber, it can take over in one year.
We have tried containing some of our exotic plants. All the following are in pots and outdoors for most of the year until the temperatures get below the mid-40s. We bring them indoors for the winter. I guess they are not invading if we invite them inside.
Syngonium palophyllum (tri-leaf wonder) is one of the easiest houseplants to grow. Stick a cutting in a cup of water and a new plant grows.
The air potato plant (Dioscorea bulbifera) looks like a weed and acts like a weed, but, of course, we grow it.
Our schefflera (S. actinophylla, sometimes called the Queensland Umbrella Tree) can take over an entire room. The Florida list makers consider the plant exotic and invasive.
Of course, there is the problem of control.
Some years after my wife died I visited a friend who said, “I think of her all the time – in exasperation! Every few months the wedelia tries to take over my lawn and I have to work so hard to remove it. I remember she gave me a cutting and told me it made a good ground cover.”
It’s nice to be remembered.
(Thanks to Emily Compost)