Away from supervision they quickly become noxious

June 11, 2009

by Barb Henry, Victoria County Master Gardener

edited by Charla Borchers Leon, Victoria County Master Gardener
How often have you acquired an unusual lovely plant, only to find it's rapidly over-growing your flower beds, choking your water features or coming up in other parts of the garden?

These just might be plants that are on the Texas noxious weeds list.

They may be manageable in our yards, but these same plants are uncontrollable when they escape into our countryside, pastures, woodlands and rivers. Away from supervision they quickly become "weeds gone wild."

Usually, it is not possible to keep them from spreading past our fenced boundaries. These are not Texas or U.S. natives, but plants that have most often been introduced from other countries and are now on the federal and/or state noxious weeds list. There are 29 of these plants that are prohibited in Texas, and the list is growing. Unfortunately, many of us are still unwittingly sharing them with friends and neighbors.


Characteristics - We are often attracted to species of invasive plants for the very characteristics that have put them on the "Invasive Noxious Weeds" list. They may be heat and drought tolerant, tolerate bogs and brackish water, may produce abundant, fast growth or thick heavy foliage.

Some have such beautiful blooms or fruit that we overlook less desirable attributes. With vigilance and constant work, we can control them in our flower beds and ponds, but in the countryside, they will crowd and shade out all the desirable native plants in their vicinity. Some invasive plants harbor disease and insects that are harmful to our native trees and crops. They crowd out and replace the native plants that provide food and shelter for birds, animals and beneficial insects. These changes can and do adversely affect the biological health of the area.

Vine, Reed, Tree and Shrub Varieties - Some vines, like kudzu, Japanese honeysuckle, Japanese dodder and cats-claw vine, kill trees by growing so thick and heavy that they totally block sunlight. Eventually, they pull down even large trees with their sheer weight.

For example, cats-claw vine is growing rampant in parts of downtown Victoria. Saltcedar, growing in some local areas near the San Antonio River, greedily sucks up all available moisture, and giant reed found in many of our ditches can grow two feet per day. Trees and shrubs like Chinaberry, Chinese tallow and McCartney rose (hedge rose) that are serious pests in parts of Victoria County, along with silk tree (Mimosa), paperbark and Brazilian peppertree, grow fast and spread quickly.

Invasive and noxious plants use up the nutrients and moisture while offering little or no benefits to surrounding flora and fauna.

Aquatic Varieties - Aquatic invasive plants have choked waterways and turned lakes and rivers into swamps and bogs, killing fish and other aquatic wildlife and plants. Some examples are the water hyacinth (a weed problem in Lake Texana), with its beautiful purple bloom and hydrilla or elodea (a weed problem in Coleto Lake), which many of us have had in aquariums and ponds for decoration, shade and to feed our fish. Water lettuce with its unusual and attractive rosette, and water spinach, also known as swamp morningglory, are both beautiful, but deadly to our waterways when they escape from our aquariums and ornamental ponds.


Some invasive and noxious plants are listed in state and federal laws prohibiting you from even possessing them. Along with that, they even carry possession fines of up to $2,000 or 180 days in jail or both. Many of these are aquatic plants. To see a list of the 13 prohibited plants, go to www.ntwgs.org/articles/illegalAquatics.html.


Use plant species that are not listed on the federal noxious weed list for your state, according to tips from www.beplantwise.org. Find out what plants are causing problems in parks or natural areas in your region. Ask a nursery about non-invasive plant alternatives.

Native plants often have similar characteristics as invasives, without the damaging ecological side effects. When traveling, check clothes, belongings and vehicles for seeds and pieces of plants that may hitchhike.

Many invasive plants are attractive garden plants and therefore may be unknowingly traded between friends - do not share cuttings, seedlings or plants that are invasive. You can check the ingredients of seed mixes to make sure invasive plants are not included.

You should buy seed and soil and potting mixes from reputable sources that guarantee the purity and content of their seed or soil mix. You can look for a tag that says "certified weed-free."

Be extremely careful with aquatic plants. Some make quite attractive additions to our gardens and aquariums but can escape your landscape spreading very quickly by producing lots of seedlings.

If you find invasive plants in your landscape, don't just collect and dump them. You can control them by hand-pulling unwanted seedlings to prevent them from growing to maturity. To prevent seeds or cuttings from sprouting, at a minimum, bag these and dispose in a landfill. It may be advisable to either freeze the specimens to destroy plant tissue or burn them if permitted.

Please be responsible. If you have a plant in your garden that has invasive or noxious tendencies, consider destroying it or at least take special steps to keep it in your garden by inserting root barriers, trimming regularly or harvesting fruits or seeds before they are spread.


Keep all this in mind next time you take a cutting from a plant you are not familiar with. Plant responsibly and refrain from keeping any plant species that are on the invasive or noxious weed list.

There are so many wonderful Texas native plants that are equally beautiful, hearty and beneficial. For ideas of natives for this area, go out to the Master Gardener Victoria Educational Gardens at the Victoria airport (across from the control tower) and visit the Texas natives section to see what these plants look like this time of year.
Common Name - Botanical Name
Balloonvine - Cardiospermum halicacabum
Brazilian peppertree - Schinus terebinthifolius
Broomrape - Orobanche ramosa
Camelthorn - Alhagi camelorum
Cat's-claw vine - Macfadyena unguis-cati
Chinese tallow tree - Triadica sebiferum
Deeprooted sedge - Cyperus entrerianus
Distaff thistle - Carthamus lanatus
Giant reed - Arundo donax
Guineagrass - Urochloa maxima
Hedge bindweed - Calystegia sepium
Itchgrass - Fottbeollia cochinchinensis
Japanese dodder - Cuscuta japonica
Kudzu - Pueraria Montana var. loata
Macartney rose - Rosa bracteata
Paperbark - Melaleuca quinquenervia
Serrated tussock - Nassella trichotoma
Torpedograss - Panicum repens
Tropical soda apple - Solanum viarum

Common Name - Botanical Name
Alligatorweed - Alternanthera philoxeroides
Eurasian watermilfoil - Myriophyllum spicatum
Giant duckweed - Spirodela oligorrhiza
Hydrilla (Florida elodea) - Hydrilla verticillata
Lagarosiphon (African elodea) - Lagarosiphon major
Purple loosestrife - Lythrum salicaria
Rooted waterhyacinth - Eichhomia azurea
Saltcedar - Tamariz spp.
Salvinia - Salvinia spp.(all species)
The Gardeners' Dirt is written by members of the Victoria County Master Gardener Association, an educational outreach of Texas AgriLife Extension - Victoria County. Mail your questions in care of the Advocate, P.O. Box 1518, Victoria, TX 77901; or vcmga@vicad.com, or comment on this column at www.VictoriaAdvocate.com.