Regional Gardening Reports :: National Gardening Association

In the Garden:
Coastal and Tropical South
January, 2009
Regional Report

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Tallow trees present their characteristic "popcorn" seed pods against a winter sky in Baton Rouge.

Kill that Plant

OK, now that I have your attention, please consider carefully this information about noxious, rampant, invasive plants that need to be eliminated from the ecosystems of our regions. Each state has a pest plant council, mostly accessible through the Department of Wildlife and Fisheries, since many invasives are aquatic plants or spread via waterways. Some plants are discouraged, others are banned from planting, and still others are the subject of public removal projects. Like all such big ideas, the reduction of invasive plants is best tackled from several angles at once, beginning in the home garden.

Plants of Concern
Widespread invaders like kudzu are always the subject of research to find a use for their abundance. A few years back, kudzu was reputed to play a role in synthesizing drugs to reduce alcohol dependence, but lately, the projects are all about its potential as a biofuel.

Such entrenched plants may prove useful eventually, but their cost to the native biota of our regions is incalculable. We'll never know how many birds didn't survive to fledge because the bugs their parents feed them no longer had a food source once invasive plants shaded out their hosts. Or how many butterfly larvae never survive to adulthood for the same reason.

Chinese tallow, or popcorn tree, is an example of an invasive plant that is on the wanted list in several states. Its seed pods are popular with birds, who spread the trees far and wide where they readily sprout on stream banks. Soon native herbaceous plants lose the battle to the woody tallows, and where this happens, bank erosion soon follows as the lower growing perennials and shrubby plants disappear. Air potato and winged yam are cousins outlawed in Florida because they both shade the native trees that they climb on, and because their brown 'taters reproduce with abandon. One becomes a hundred in a season and with no predators to eat them, the multiplication continues.

Know the Enemy
When identifying an invasive plant, be sure to ask, "Which is that?" Littleleaf or Chinese privet is on every list of plants that have invaded the Southeast, yet it remains in thousands of landscapes in both solid green and variegated form. Avoid it, but know the difference between it and Japanese privet, or ligustrum. The latter is larger leafed, shiny, evergreen, and a stalwart as a hedge or small tree at the back of a border. If you have Chinese privet, pull it up. If that is impossible, at least cut the flowers off before they open in spring. Although the plants spread underground, the fruit that follow the flowers are eaten by birds, thus much more widely dispersed.

Japanese honeysuckle is pernicious, as anyone who has tried to untangle its mess from an azalea can tell you. It spreads underground throughout gardens and woods, and occasionally adorns an old piece of equipment abandoned in a pasture. Like most invasives, its original importation was heralded for fast growth and abundant flowers. Remove it by digging up the vine's roots as much as possible. Simply cutting it down is ineffective unless you then cover it with a heavy statue.

Animals Spread Invasives
It's not as if we gardeners have exclusive control over where our plants and their progeny end up. Removing plants like privet or air 'taters can simply transplant them to public landfills or compost heaps. It's better to burn them, but that is illegal in most places.

More than our immediate actions, however, we contribute to the spread of invasive plants by hosting the wildlife that carry their seeds far and wide. From the obvious birds that often participate in seed germination by the actions of their digestive systems to the less apparent bunnies whose fur is easily grabbed by spurred seeds, critters transport plant parts. Just confirmed last year, even earthworms inadvertently move seeds for miles, trapped in the folds of their bodies. It's a big problem, and each small step we take to turn the tide can add up to healthier ecosystems where we live.

Habits to Cultivate
Keep an ear to the issue: Subscribe to Invasive Species News at or add a news alert for invasive plants in your state or zone to your favorite search engine and get stories delivered to your emailbox. Watch new pots and remove weeds or "hitchhiking" plants if you do not know their identity. When you find invasive plants in your own garden, remove them. If they are featured in public plantings, take pictures and send a note to the entity with information explaining the problem. Be an activist, or we'll all get choked by tallow trees and Japanese honeysuckle.

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