What Is An Invasive Plant, And Why Should We Care?

When non-native or exotic invasive plants are introduced to an area and have no natural predators, they can displace native species. Many of these were intentionally brought to southeastern North America as ornamentals from other continents. While they often have attractive flowers, foliage, or fruit, “invasives” disrupt natural ecosystems, wildlife food sources and habitats, water flow, and soil health. Invasive exotic plants may also produce lots of seeds and spread them into woodlands. Some examples are Bradford pear, privet, wisteria, and Chinese elm. Others produce a thick canopy and shade out native species or substances that prevent seed germination (kudzu and tallow tree).

Callery pears in bloom, spreading along the edge of woods in Upstate South Carolina.Joey Williamson, ©2012, HGIC, Clemson Extension

Callery pears in bloom, spreading along the edge of woods in Upstate South Carolina.
Joey Williamson, ©2012, HGIC, Clemson Extension

“Beauty is only skin deep” and “Pretty is as pretty does” are two sayings that I heard as a child growing up. Beauty alone should not be the only justification for selecting a plant for the landscape. Studies have shown that birds need a lot of insects to feed and fledge their chicks, with at least 70% native vegetation. Native shrubs, vines, and trees support insects, such as adults and larvae of beetles, butterflies, moths, ants, and flies. Certain insects depend on native flora as hosts for the larval stage and the berries and seeds for adults. Food webs depend on plants for energy, oxygen, and carbohydrates. Decomposing leaves build soil; the leaf litter and humus are essential to the microbes that recycle those nutrients.

Right Plant Right Place

When selecting plants to use in the landscape, one must consider form, mature height and width, site conditions like light, moisture, and hardiness. Just as important as those considerations are the ecological services that a species can deliver. There is a native plant for every niche and microclimate of your landscape. There are communities of plants that want to grow in hot, muggy shade or in full sun, and other groups that will thrive in a floodplain or marsh.

Our native grasses, perennials, trees, shrubs, vines, and groundcovers are often the best choices for preserving ecosystems, use fewer pesticides, and irrigation because they are adapted to the climate, heat, and humidity of our region.

Knowing what to ask for when working with a landscape designer or shopping at a garden center is key. Common names can vary regionally, so knowing the scientific name (genus and species) will avoid any confusion. There are many species of oaks, hollies, and laurels, and sometimes the common name or scientific name may indicate the origin of the plant, for example, Chinese holly (Ilex cornuta) or American elm (Ulmus americana). There are some excellent lists by region and sites, and most of the common natives are carried by garden centers, native plant sales, and arboreta. There are several southeastern mail order companies that carry unusual species and named varieties of more common ones.

Attractive not only to birds, butterflies, and other wildlife, native herbaceous and woody species can give seasonal interest and beauty. Flowering perennials, such as coneflower, passion vine, and lobelias, appeal to gardeners and offer another way to attract creatures other than just having feeders. Plant them (native plants), and they (birds, bees, and butterflies) will come.

Think globally, plant locally.

If this document didn’t answer your questions, please contact HGIC at hgic@clemson.edu or 1-888-656-9988.

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