I frequently have conversations with people about plants. Plants they have on their property, or are considering growing, or the names or characteristics of plants. During the conversation I usually mention that this or that plant is a native or it is an exotic (introduced from far away). Very often my comment is greeted with a blank stare or a
quizzical look as if to say, “What difference does that make?” Or, “Who cares?”
Well, actually, it makes a big difference. Here’s why. Native plants grew up here. They evolved to live here in our soil, with our climate, our insects, our animals and all the other native plants. And they have been doing so for thousands of years. At the same time that our native plants were evolving to live with everything else living here, everything else was evolving to live with the native plants. In other words, they all co- evolved together, to live together, to survive together, to succeed together. If they had not succeeded, we wouldn’t have them today.
So native plants evolved to live with our native birds, and our birds evolved to live with our plants. Native insects have built into their DNA which native plants are good to eat. Their DNA won’t recognize non-native plants as food. If non-native plants crowd out native plants that certain insects feed on, then the insects die. You may say, “So what? I don’t like bugs anyway!”
But the bugs that die out were the food for certain birds, lizards, frogs and toads, and the birds, lizards, frogs and toads were food for other native animals. Or the caterpillars that fed on a certain native plant which was killed out by an exotic plant, may have been the same insect that in an adult stage was needed to pollinate certain wildflowers or fruit-bearing trees.
What I am really saying is that the introduction of non-native plants disrupts the long- established natural food web and the symbiotic relationships that have been established over the millennia. We know enough about natural ecosystems to know that we don’t know enough to make intentional substitutions of one organism for another. We know of many examples where the unintentional displacement of native plant species by non- native plant species has led to significant problems.
The above disruptions are exacerbated by the fact that many exotic plants become invasive when introduced into our local ecosystem. Whatever kept the uncontrolled spread of that plant in its native land (climate, specific insect pests, other plant competitors, certain herbivores) is lacking here. So the exotic outcompetes with at least one native species, the latter is eliminated, and the exotic takes over the space, but not the function, of the native plant.
So now in place of willows, sycamores, cypress, sedges, rushes, bushy bluestem, eastern gamagrass and buttonbush, we have creeks lined with giant reed (Arundo donax), which nothing eats, nothing lives in, and we can’t even see the water anymore!
The worst offending invasive exotic plants include Chinaberry, Chinese tallow, ligustrum, vitex, and of course the before mentioned giant reed. In ponds and lakes water hyacinth and giant salvinia are the worst.
Away from the water the biggest problems are caused by Bermudagrass, Johnsongrass and KR bluestem, nandina, musk thistle, bamboo, Japanese honeysuckle, Chinese parasol-tree, and tree-of-heaven.
Our Hill Country ecosystem is under enough challenges already with past, and sometimes current, overgrazing, too many deer browsing out many native trees and shrubs, native cedar encroachment, drought and the increasing human population.
I should expand a little on cedar—it is native! It was here when the first settlers arrived. It belongs in our native habitat, and it is only when conditions have been such as to allow dense cedar brakes to form that cedar has become a problem.
So, it is important for everyone to get to know our native plants, to be on the lookout for exotics and avoid them or destroy them if possible, and to understand why it is important.
Removing an invasive plant colony can prove to be very difficult and expensive, sometimes essentially impossible and it sometimes means using chemicals no one really wants to use. A far better way to control the spread of exotic plants is to not ever allow them to be here in the first place. But our laws do not prohibit their importation and sale. They wouldn’t be for sale, or course, if people didn’t buy them, and thus the problem starts when people ask the question, “who cares?” Instead, the question to ask before you buy is, “Is it native to the Hill Country?”
Until next time…
View & download the PDF here: What is So Important About Native Plants
Jim Stanley is a Texas Master Naturalist and the author of the books “Hill Country Ecology,” “Hill Country Landowner’s Guide” and “A Beginner’s Handbook for Rural Texas Landowners.”
He can be reached at firstname.lastname@example.org.
Previous columns can be seen at http://www.hillcountrynaturalist.org .