This is a topic I have discussed before, but it is a message that needs to be repeated. Simply put, for the health and sustainability of the local ecosystem, native plants are essential and nonnative plants are either mildly or severely detrimental.
Unfortunately, most of us grew up and learned whatever we know about plants and gardening without any regard to the distinction between natives and exotics. And, to be fair, the importance of that distinction had not been known or discussed by the general public until the last 20 or 30 years. So it is still somewhat of a new concept to many people.
So, why are native plants preferred, and what is wrong with exotic or non-native plants? There are several reasons.
Native plants grew up here. That means they evolved to live here successfully, long term, without dying out due to competition with other plants or being eaten to extinction by native animals. It also means that they did not become invasive and crowd out other native plants under the ecological conditions that have existed here for a long time. It also means that native plants have been successfully reproducing in this area, which for some plants means that the pollinators of those plants have also survived to still be around. And finally, it means that native plants have survived and reproduced in the Hill Country or Edwards Plateau with our soil and climate, droughts and floods included.
The introduction of any non-native species into a local ecosystem represents an upset and a threat to the continued successful sustainability of the local ecosystem. Most exotic plants just take up space and compete for water and minerals with native plants, but otherwise do no harm. But they may also not have any benefit for any of the native flora or fauna.
Some non- native plants, however, may out-reproduce native plants and become invasive, choking out whole collections of native plants, forming a monoculture that may have little or no benefit for local wildlife and completely altering the local ecosystem. Tamarisk (salt cedar), giant reed (Arundo donax), Chinese tallow, water hyacinth, and giant salvinia, are common examples in Texas, and there are dozens more species that cause serious damage and disruption of native areas.
Finally, many of the plants one finds for sale in this area are native to parts of the world that usually get more rainfall than we have in the Hill Country, or have lower pH soils, or require more of some minerals than are available here. So when folks try to grow them, they wind up using more water, fertilizer and other additives in an attempt to keep the exotic plants healthy. Native plants, once established and planted in the right soil in the right location, should need little if any extra water and no fertilizer. So natives help us preserve our precious water supply.
So what is the definition of a non-native plant? Anything that historically did not grow in this area. That obviously means that anything that originated in Europe, Asia or Africa. But it also means anything that is native to Florida, Washington, Tennessee, or for that matter East Texas or the Gulf Coast, but has not historically grown here, is in fact a non-native plant and should be considered a potential invasive pest.
It is worth pointing out that the introduction of foreign exotic plants is not limited to Texas or the U.S. Australia has had huge problems caused by the introduction of prickly pear cactus from, guess where! The problems and the principles of introduced exotics work both ways.
I have asked myself many times why non-native plants appeal so much to so many people, and I have never really come up with an answer. I think part of the problem is that the things people see around them all the time seem commonplace to them and they are searching for something striking or unusual—something exotic! But given the collection of native wildflowers we have witnessed this spring just growing along the roadside, I can’t imagine anything more striking than that.
Another part of the problem may be that one finds non-native plants for sale at many more places and more often than native plants, so one has to work a little harder to find natives.
But for the sake of our water supply and the health of our native ecosystem, I urge everyone to make the effort to find and buy natives.
Until next time… Jim Stanley is a Texas Master Naturalist and the author of the book “Hill Country Landowner’s Guide.” He can be reached at jstmn@ktc.com.