The Nature of Eureka: Noxious invasive aliens


I know, I know, as a card-carrying charter (and now life) member of the Arkansas Native Plant Society, a Master Naturalists in training, and a general advocate of native plants, I’m supposed to have a prejudice toward and abhorrence to aliens, immigrants from other parts of the world which have adapted to our homeland – ironically our homeland by virtue of being invading aliens. Why is it then, when I go to a nursery, or go to buy plant at a garden center, the clear majority of plants are introduced from other parts of the world? Why is it that most of the plants that we grow in gardens are aliens?

This also begs the question, at one point in geological history do we use as the starting point for determination of native or non-native? Take those trees now blooming with the big purple flowers, candelabra tree, princess tree or Paulownia (Paulownia tomentosa). Is it a non-native invasive alien from China, or is it a plant that was just reintroduced because as some point and by some event, it became extinct in the state (then reintroduced) just like bears, elk, wolves and other beings perceived as a threat? Any Quapaw or Osage residents in your neighborhood? Actually, Paulownia, did occur in North America (perhaps in Arkansas) during the Tertiary period, about 65 million years ago, about the same time that dinosaurs disappeared.

Paulownia, itself, as we now know it, was introduced into North American horticulture around 1844. Then considered an ornamental and shade tree, the fast-growing tree with big leaves and purple flowers was planted in much of North America, Europe, Japan and Korea. It produces an abundance of seeds and reproduces from just a cutting of the root, then if you cut it down re-sprouts from suckers. It’s adaptable. In some states it is deemed a “noxious” species and banned from the nursery trade. How arbitrary. We have such short memories! Its ancestors were native plants only 65 million years ago, a blip as measured in geological time!

Here in the Ozarks, Paulownia seems to be just a scattered pretty tree here and there, doing no particular obvious harm. The problem that has created invasive alien plants in North America is invasive alien humans (mostly from Europe). What defines an “alien” be it botanical or human, is fraught with ambiguous concepts of time and space.