Why are formerly promoted plants now on the invasive list?
A viewer recently asked about why certain trees or other plants that were once highly promoted are now on the invasive plant list? And, many of them are still sold in nurseries.
Well, just as beauty is in the eye of the beholder, the interpretation of the term “invasive” is subjective, and often depends on the environment. A plant that is invasive in one situation may be much less so in others. Rainfall and soil type will influence this quite a lot.
A plant that is invasive here in Central Texas may be much less so, or not at all, in the sandy soils and xeric climate of far West Texas, and those same characteristics that lead a species to earn the “invasive” label here, may be prized in areas where other plants are challenging to grow.
Most plant species that are labeled “invasive” are not native to the region where they’ve been given this negative description.
So then, are native plants not considered invasive? Not usually. In the case of native plants, instead of “invasive,” you will often hear the label “aggressive” used.
Now, to the untrained ear, those two adjectives may not sound all that different. But to plant people, they are. One big difference is that “invasive” species are known to escape confinement, into unwanted areas. And when they get out of your yard into your neighbor’s or a greenbelt, they tend to take over and choke out native species, thereby effecting the entire microclimate in that area, and most likely also effecting the delicate balance of wildlife living there.
Again, in far West Texas, where there is much less rainfall, an “invasive” plant may thrive with very little care or supplemental irrigation. Although we’ve received adequate rainfall this year, it hasn’t been that long since Central Texas was in a severe drought and we were all rethinking our landscapes for water conservation.
Which leads us full circle back to the question of why many “invasive” species are sold in nurseries. The situation is a delicate balance, and in general, we should avoid plants that are considered invasive where we live. And as a final note, we should mention the category of “noxious weed,” which is a designation given to plants that are illegal in certain regions. Those species have been shown to severely affect not only the natural areas, but also commerce. Just think “Kudzu.”