Some non-native plants introduced into our landscapes as ornamentals have escaped to become invasive weeds with negative impacts to our native plants and animals.

How do non-native invasive plants harm the environment?

• Crowd out and displace native plants
• Reduce natural regeneration of forests and other natural areas
• Do not support insects at the bottom of the food chain, harming the birds and animals that depend on the insects
• Change fire, nutrient, and water cycles

What characteristics suggest that a non-native plant may become invasive?

• Grows quickly and aggressively
• Produces a lot of seeds
• Self sows easily
• Has seeds spread by birds, animals, wind, or water
• Sprouts readily and prolifically when cut
• Responds favorably to disturbance
• Tolerates harsh environments

Why is it important to include native plants in landscapes?

• Native plants support the insect species that provide food for birds (especially baby birds), other insects, and small animals.
• Native plants provide the foundation for a more balanced and diverse habitat.

The Challenge

Remove invaders from your landscape and replace them with native species or safe non-natives. Maintain a generous proportion of natives in your landscape to support insects, birds, and a balanced ecosystem.

Know what you grow!

Chinese privet (Ligustrum sinense)

This mostly evergreen shrub spreads by abundant seeds carried by birds and water. Prolific root sprouting adds to its spread and difficulty of control. Privet has some value as deer browse and bird habitat, and the flowers do attract bees. But the dense infestations displace most native species and reduce native bee populations.

Callery or ‘Bradford’ pear (Pyrus calleryana)

The popular cultivar ‘Bradford’ was considered sterile, but with the introduction of new cultivars, seeds are now produced in abundance. Spreading rapidly, escaped Callery pear trees are most noticeable when blooming in the spring. Naturalized plants often have thorns.

Chinaberry tree (Melia azedarach)

Once a favorite around old homesites, Chinaberry has escaped cultivation, becoming common along roadsides, fence lines, and forest edges. Abundant seeds are spread by birds and are poisonous to humans and livestock. Restricts growth of nearby native species.

Non-native wisterias (Wisteria sinensis & W. floribunda)

The natural hybrids of Chinese and Japanese wisteria are more invasive than either individual species. Woody vines form dense infestations that are difficult to control. Vines bloom in the spring as the leaves emerge. Native wisteria (W. frutescens) blooms during the summer after leaves are developed.

Mimosa or silktree (Albizia julibrissin)

An old homesite favorite, mimosa is now commonly seen along roadsides, open areas, and disturbed habitats. Abundant, long- lived seeds and prolific sprouting from cut stumps contribute to its spread.

Leatherleaf Mahonia [Berberis bealei (syn. Mahonia bealei)]

An evergreen shrub with leathery, spiny leaves, leatherleaf mahonia spreads by bird-dispersed seed. Seed from ripe fruit can germinate immediately. Prefers moist soil, but escaped plants have established across a wide range of soil and light conditions.

Thorny olive or silverthorn (Elaeagnus pungens)

Tolerant of a wide variety of habitats, thorny olive is spread by animal- dispersed seeds and stem sprouts. New growth aggressively climbs into and over shrubs and trees. It is difficult to control once established.

Nandina or Heavenly bamboo (Nandina domestica)

Promoted as a tough evergreen shrub with red berries, nandina has naturalized and invaded natural habitats, displacing native species and disrupting plant communities. Sterile, noninvasive cultivars are available. When eaten in large quantities, the berries can be toxic to some species of birds.

Chinese or lacebark elm (Ulmus parvifolia)

Adaptable to a wide variety of habitats and not susceptible to Dutch elm disease, Chinese elm has been widely planted as a street tree. However, prolific windblown seeds develop into aggressive seedlings that are difficult to control.

Beware!

These non-natives are showing signs of becoming invasive or are already established invaders.

A Cautionary Tale

Chinese tallowtree (Triadica sebifera), also known as popcorn tree, is a classic example of a plant introduced into the United States with good intentions, but with very bad outcomes. Benjamin Franklin is often cited as having introduced tallowtree in 1772. It was promoted by Franklin and others for numerous purposes, including as an ornamental.

Strong control efforts are needed to slow its spread!

For more information, visit the following websites:

Invasive Plants

• Alabama Cooperative Extension System Invasive Plants
• Alabama Invasive Plant Council
• Center for Invasive Species and Ecosystem Health
• A Field Guide for the Identification of Invasive Plants in Southern Forests

Native Plants

• Alabama Plant Atlas
• Alabama Smart Yards
• Bringing Nature Home
• Brooklyn Botanic Garden
• Lady Bird Johnson Wildflower Center

 

 

---

Nancy Loewenstein, Extension Specialist, Forestry, Wildlife and Environment, and Danita Smith, former curator, Davis Arboretum, both with Auburn University.

Revised February 2024, Invasive Plants: Exotic Beauties Can Have Devastating Results, FOR-2043