Purple loosetrife, Lythrum salicaria, a non-native species considered invasive.
by Jo Ann Allen, Lafayette County Master Gardener
In my conversations with other Southern gardeners I have never met one interested in planting privet or kudzu. It is their aggressive invasiveness that is the big put-off. But those aren’t the only baddies we should avoid. There are 450 or so exotics, imported to the United States as ornamental plants that are wreaking havoc on our nation’s flora and fauna. And, sadly, many of these plants are still being sold in plant nurseries.
The scary feature of invasive plants is their ability to compete above and below the ground and outgrow surrounding plants. The concern is that invasive plants can overpower native species and cause soil erosion, create fire hazards, deprive animal and insect life of food and shelter, and have a negative impact on fisheries, recreational areas, and public water supplies. A good example of this negative affect is the spread of the beautifully flowered Purple Loosestrife. One mature plant can produce over two million seeds, all with a high germination rate. It is estimated that over 4 million acres are now affected by Purple Loosestrife’s escape from the garden and it is costing an estimated $45 million dollars annually in control efforts.
Regional, state, and federal agencies have developed to raise public awareness about this growing problem. One of their stands is that gardeners need to understand “the realm of their gardens extend past the boundaries of their own land.” In being responsible Mississippi gardeners we must know our enemies. Mississippi State Extension Services list these plants as invasive in Mississippi:
- Chinese Privet (Ligustrum japonica) has displaced the native shrub layer in 2.4 million acres of land in 5 southern states.
- Purple Loosestrife (Lythrum salicaria and L. virgatum) was introduced as a garden plant to the U.S. in the 1800s. Its spread is now reaching Mississippi.
- Water Hyacinth (Eichornia crassipes) was imported in 1884 as an aquatic ornamental. It is now considered “the world’s worst water weed” and one of the fastest growing plants known.
- Chinese Tallow Tree (Triadica sebifera) its colorful fall foliage and rapid growth make it a popular ornamental tree. It reproduces and spreads quickly and is difficult to control due to its long taproot.
- Cogon Grass (Imperata cylindrical) imported in the 1900s; it has been promoted as a forage plant as well as an ornamental. It is known as “the seventh worst weed in the world.” It is a serious fire hazard because it burns hotter and more frequently. It is still being sold in nurseries as “Japanese Bloodgrass” and “Red Baron Bloodgrass.”
- Tropical Soda Apple (Solanum viarum) discovered as an invasive in 1988, this plant often infests pastures and crowds out natives and forage plants for livestock.
- Alligator weed (Alternanthera philoxeroides) is an aquatic and terrestrial plant that clogs waterways and has no food value to wildlife
- Kudzu (Pueraria lobata) enough said!
What actions can we take to help prevent the spread of invasive plants? The first steps are to become familiar with the invasive plants that threaten our region, refrain from planting invaders and remove and destroy known invasive plants on our property. We can also help by educating our families, neighbors, and friends about this plight. A good source for information on this subject is the National Invasive Species Information Center at www.invasivespeciesinfo.gov/.
