An “invasive species” is defined as a species that is non-native (or alien) to the ecosystem under consideration and whose introduction causes or is likely to cause economic or environmental harm or harm to human health (Executive Order 13112).
An invasive species grows/reproduces and spreads rapidly, establishes over large areas, and persists. Species that become invasive succeed due to favorable environmental conditions and lack of natural predators, competitors and diseases that normally regulate their populations. Not all non-native species are bad, but some plants that look lovely in your garden might be harmful invaders that will make their way into natural areas (texasinvasives.org).
Terrestrial Invasive Species
One very common invasive plant in the KW neighborhood is the cats claw vine (Macfadyena unguis-cati, native to West Indies and Mexico to Argentina), a high-climbing woody vine that can grow up to 50 feet long. It gets its name from the claw-like climbing appendages that are used to grasp onto surfaces. Its yellow flowers are trumpet shaped, 3 inches long and 4 inches across. It is very similar in appearance to the cross-vine (Bignonia capreolata), but the cross-vine has red-orange flowers. Cats claw is particularly nasty as it has many ways to spread and propagate: its fruit capsules are linear and flat, roughly 20 inches long, containing oblong, winged seeds that are wind-dispersed. It develops deep tubers on the root that can be as big as sweet potatoes, and are very difficult to eliminate.
Cats claw vine is long-lived and grows relatively slowly. Due to its rooting abilities, a dense mat of it can cover the ground and smother native vegetation (you can see an extreme example of this at the house at the corner of Washington and Beauregard). River and stream banks are particularly susceptible to cats claw invasion, as can be seen on a couple of the bald cypress trees along the river across from Blue Star.
The Invasive Plant Database has identified these other plants as “particularly worrisome terrestrial invasive species” in the Edwards Plateau and South Texas Plains ecoregions:
Brazilian peppertree - Schinus terebinthifolius
Buffelgrass - Pennisetum ciliare
Chinaberry tree - Melia azedarach
Chinese tallow tree - Triadica sebifera
Common water hyacinth - Eichhornia crassipes
Elephant ears - Colocasia esculenta
Giant reed - Arundo donax
Glossy privet - Ligustrum lucidum
Golden rain tree - Koelreuteria paniculata
Guineagrass - Urochloa maxima
Heavenly bamboo - Nandina domestica
Hydrilla - Hydrilla verticillata
Japanese honeysuckle - Lonicera japonica
Johnson grass - Sorghum halepense
King Ranch bluestem - Bothriochloa ischaemum var. songarica
Paper mulberry - Broussonetia papyrifera
Popinac - Leucaena leucocephala
Salt cedar - Tamarix ramosissima
Tree of heaven - Ailanthus altissima
Water lettuce - Pistia stratiotes
Some alternatives to these invasive plants are listed here: www.austintexas.gov/sites/default/files/files/Watershed/growgreen/plantguide. One of my faves is the pipevine (Aristolochia fimbriata) – it has the added bonus of being the food source for beautiful pipevine swallowtail butterflies!
Adapted plants are not native and not invasive, but are able to thrive in the local climate and soil conditions. Some common landscape plants in our area that are adapted (not native) include:
Crepe myrtle – India, southeast Asia
Butterfly iris – southern and central Africa
Bulbine – South Africa
Boxwood - China, Korea, Japan
Stevia – Brazil, Paraguay
Loquat – south central China
Bradford pear – China, Vietnam
Plumbago – South Africa
“Native plants are the foundation of the biodiversity that maintains our own life support systems. They nurture important pollinators like bees, butterflies, and hummingbirds. Native plants create a distinctive sense of place, preserving the natural character of your region.” (landscapeforlife.org/plants/use-native-and-adapted-plants)
- Susan Athené