Story and photo by Anita Westervelt, Texas Master Naturalist
Native plants are those naturally occurring in an area without human introduction. Invasive plants, on the other hand, are non-native species that are able to establish themselves within existing native plant communities and can become a threat to the integrity of the ecological community.
A plant that is considered invasive in the Rio Grande Valley is, of course, native somewhere. Take for instance coral vine with its beautiful, hot-pink flower clusters and big, pretty green, heart-shaped leaves.
But for all its beauty, out of its native territory and into an overly hospitable environment like the Rio Grande Valley, it just might wreak havoc. With plants, you never know what might be going on below the surface of the soil.
Coral vine has several common names like queen’s wreath, corona de reina, hearts-on-a-chain, and Mexican creeper. Its botanical name is Antigonon leptopus. It is native to Mexico and Guatemala. It was introduced to the United States and is now found in the Gulf Coast states, and also in Arizona and South Carolina. It is considered a particular problem in Hawaii. As a matter of fact, it is considered an environmental weed in many parts of the world — to the extent that it is included in the Global Invasive Species Database.
That status begs the question: just what does a plant have to do to become so unpopular? Coral vine has a long list of negative attributes. It can completely smother native plants and out-compete native vines and understory vegetation, according to a BioNET-eafrinet fact sheet.
The vine wends its way to the top of trees, seeking sun, where it sends out new growth from the vine stem. Because it eventually restricts sunlight to the vegetation beneath it, it eventually kills what it covers.
In some countries like Brazil, India and Malaysia, the flowers are a major source of nectar for honeybees. In Columbia, Cuba, Mexico and the southern United States, they are only a minor source.
The vine is a prolific bloomer and seed producer which furthers its invasiveness; a wide range of animals, including raccoons and birds, help spread the seeds. The seeds float on water and remain viable at their ultimate destination.
Underground, the plant forms large tubers and massive rootstock which also produces suckers. Even if the coral vine is cut back, or damaged by frost, the tubers will re-sprout. Once established, digging up the root-base and tubers becomes quite a major project.
One thing gardeners can do before they put their garden at risk by planting invasive plants is to do a little research.
Putting the common name and scientific name into a search engine will bring up links. Most plant sites mention where a plant is native. Some sites list comments from others who have had experience with a plant in their own garden.
A valuable website to check if a species is invasive in Texas is www.texasinvasives.org. The site’s invasive database allows further research by using either the plant’s common name or scientific name.