Mississippi's 10 Worst Invasive Weeds

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They all threaten the biological diversity that is the heritage of Mississippi

Mississippi is being silently invaded by exotic plant species. These weeds are not just garden nuisances; they are changing the way natural areas function, and they are costing all of us money. Your tax dollars pay to fight the disruptive spread of these plants. Also, tax revenues are lost when plants such as kudzu invade forested timberlands.

This invasion has gained momentum since the last century when many of these plants were first imported or accidentally introduced. It is estimated that 100 million acres in the United States are already affected by invasive exotic plants. This acreage increases annually by an area twice the size of Delaware. Almost 20 percent of the plant species in Mississippi forests, parks, refuges, and other open spaces are not native to our state. Some of these exotic plants meet few natural constraints and can soon dominate a landscape.

The “10 worst weeds” described in this publication are biological pollutants that crowd out native plants, degrade wildlife habitat, and threaten many endangered species. Many of these plants are familiar sights on our landscape. All of them threaten the biological diversity that is the heritage of Mississippi.

Alligatorweed

(Alternanthera philoxeroides)

Native to South America. Appeared in the United States about 1890.

Alligatorweed is becoming a serious pest in south Mississippi where it occupies large areas of wetlands that would otherwise be available to native wetland plants. It can grow in dry fields or in water. It generally grows as a mat of interwoven plants. A South American leaf beetle introduced in the 1980’s for biological control of alligatorweed has reduced the spread of this plant but has not eliminated it.

Chinese Privet

(Ligustrum sinense)

Native to China. Introduced in the United States as an ornamental shrub in 1852.

Found throughout the South, Chinese privet forms dense thickets along roadsides, fence rows, fields, rights-of-way, and in forested creek bottoms. These shrubs typically reach 10 to 20 feet in height with numerous branches. A member of the olive family, privet produces seeds abundantly and regenerates by root sprouts quickly forming dense stands. Because of dense stand production, privet crowds out native plants and trees, especially hardwoods. Privet typically produces small white flowers in early summer and terminal clusters of seeds in the fall. Seeds are consumed primarily by birds and disseminated.

Chinese Tallow Tree

(Popcorn Tree)
(Triadica sebifera)

Native to Eastern Asia. Imported to South Carolina in the late 1700’s and later used in soap-making.

The colorful fall foliage and rapid growth of Chinese tallow make it popular as a landscape tree. It reproduces easily, spreads quickly, and is difficult to control because of its long taproot. Several states are in the process of banning sales of Chinese tallow after widespread invasions of wetlands from Texas to Florida.

Cogongrass

(Imperata cylindrica)

Native to Southeast Asia. Arrived accidentally as packing material into Mobile Bay, Alabama, in the early 1900’s. It was later promoted as a forage grass and as an ornamental.

Classified as the seventh worst weed in the world, cogongrass is hardy and tolerant of shade, high salinity, and drought. It forms dense mats that crowd out native vegetation and forage plants and displaces ground-nesting species, such as turkey and bobwhite quail. It can alter the natural fire regime by causing hotter and more frequent fires. Note: Cogongrass is still sold as an ornamental under the name of Japanese bloodgrass or “Red Baron” bloodgrass.

Japanese Honeysuckle

(Lonicera japonica)

Native to Japan. First introduced to Long Island, New York, in 1862.

Japanese honeysuckle is a familiar plant in the southern landscape where it provides year-round forage for deer and other wildlife. It is common along fence rows, forest openings, and disturbed areas. However, this plant’s dense growth crowds out native vegetation, reduces the variety of native plants available to wildlife, and can stunt or kill growing trees. Note: Coral honeysuckle, Cross Vine, and Virginia creeper are useful native vines for home landscaping instead of exotic Japanese honeysuckle.

Johnsongrass

(Sorghum halepense)

Native to the Mediterranean region. Came to the United States as a forage plant in early 1800’s.

Johnsongrass has spread throughout most of the temperate area of the world. Growing 8 feet tall and forming almost pure stands, Johnsongrass is a serious weed of row crops, pastures, and roadside rights-of-way throughout Mississippi. Spreading by prolific seed production or fleshy, underground rhizomes, Johnsongrass stands along highway rights-of-way can provide hiding sites for wildlife or limit visibility of passing motorists. Rank growth or growth that occurs under poor environmental conditions can cause cyanide poisoning in animals, and can be especially dangerous to ruminants.

Kudzu

(Pueraria lobata)

Native to Japan and Asia. Showcased as an ornamental at the Philadelphia Centennial Exposition in 1876. In Mississippi, it was planted to control widespread soil erosion that plagued the state in the last half of the 19th century and the first half of the 20th century.

No list of Mississippi weeds would be complete without the “Plant that Ate the South.” During summers, kudzu grows up to a foot a day, covering trees, buildings, fences, and telephone poles. Kudzu damages structures and eventually kills trees and understory growth. This vine has caused more than $100 million in damages.

Purple Loosestrife

(Lythrum salicaria)

Native to Eurasia. Introduced for ornamental and medicinal uses in 1800’s.

This troublesome species is just reaching Mississippi following a widespread invasion of the northern plain states. A deceptively beautiful flowering plant, purple loosestrife can completely take over wetlands where it crowds out native plants and negatively impacts native fish and wildlife. Purple loosestrife covers about 4 million wetland acres nationally and costs about $45 million a year in control efforts. Early detection and aggressive local control will be the key to keeping this plant from spreading in Mississippi. Note: Research has shown that “sterile” varieties sold in nurseries can still reproduce and become invasive.

Tropical Soda Apple

(Solanum viarum)

Native to Brazil and Argentina. First recorded in Glades County, Florida in 1988.

Within 7 years of its arrival, tropical soda apple invaded an estimated 1 million acres in five southern states and Puerto Rico. It spreads by interstate movement of cattle, hay, and composted manure from infested areas. This prickly plant replaces edible forage plants and hampers livestock and wildlife movement. It is a serious threat for vegetable growers, livestock producers, and land managers.

Water Hyacinth

(Eichornia crassipes)

Native to the Amazon Basin and South America. Imported into the United States as an aquatic ornamental in 1884.

Water hyacinth may be the world’s worst aquatic weed. Sold as a water garden ornamental famous for its beautiful flowers, it has escaped into wetlands and waterways across the globe. One of the fastest growing plants known, it displaces native plants, fish and wildlife, disrupts water transportation, disturbs recreational fishing, and blocks water intakes at hydroelectric power-generating dams. At one time in Florida, 125,000 acres of open water were covered with up to 200 tons of water hyacinth per acre.

You Can Help Stop The Invasion!

More information on invasive weeds is available at these and other internet web sites:
http://msucares.com
http://www.tnc.org/
www.blm.gov/weeds
http://www.se-eppc.org/
http://plants.usda.gov/plants/
http://www.tncweeds.ucdavis.edu

This brochure is provided through a cooperative effort by the following agencies:
Bureau of Land Management
Mississippi State University Extension Service
The Nature Conservancy
U.S. Forest Service
USDA Agricultural Research Service

Resources:
University of Florida, Center for Aquatic Plants
Mississippi State University Extension Service
The Nature Conservancy
Native Plant Conservation Initiative
State Natural Heritage Programs
Plant Conservation Alliance

Production and printing by Mississippi State University.

Compiled by Faye Winters, District Wildlife Biologist, Bureau of Land Management; John D. Byrd, Jr., Extension Weed Specialist, Mississippi State University; and Charles T. Bryson, Research Botanist, USDA-ARS.

Mississippi State University does not discriminate on the basis of race, color, religion, national origin, sex, age, disability, or veteran status.

Miscellaneous 1194
Extension Service of Mississippi State University, cooperating with U.S. Department of Agriculture. Published in furtherance of Acts of Congress, May 8 and June 30, 1914. Joe H. McGilberry, Interim Director

(4M-07-01)

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