We are now learning that the introduction of foreign plants into new locations can have its drawbacks. Plants, kept in check by limited soil, rain, hungry bugs or animals in their native habitat may run rampant elsewhere without those controls. One only has to mention "kudzu" to any Southerner to elicit a groan of horror. This vine, brought to the United States as an ornamental, arrived without the insect predators that kept it under control in its native Japan. Now, it smothers the Southern landscape.
Troublesome plants in areas foreign to them are labeled invasives. Non-native plants that are invasive grow rapidly and displace native plants in natural areas.
Some of these intruders have long been available for the home landscape in local nurseries. Many of these plants spread rapidly and upset the complicated balance between native plants and wildlife. The pollen from these intruders may also alter the genetic makeup of native plants.
Soil and climate help or hinder these plants from spreading, so the plants defined as invasive vary from region to region.
In the Middle Atlantic states, the following plants have been identified as "plant invaders" of natural areas. For instance, the Norway maple, even though it is beautiful, can displace our native sugar maple.
Garlic mustard (Alliaria petiolata)
Japanese knotweed (Polygonum cuspidatum)
Purple loosestrife (Lythrum salicaria)
Lesser celandine (Ranunculus ficaria)
Canada thistle (Cirsium arvense)
Chinese lespedeza (Lespedeza cuneata)
Chinese silver grass (Miscanthus sinensis)
Common day lily (Hemerocallis fulva)
Common reed (Phragmites australis)
Giant reed, wild cane (Arundo donax)
Autumn olive (Elaeagnus umbellata)
Bush honeysuckles, exotic (Lonicera species)
Japanese barberry (Berberis thunbergii)
Multiflora rose (Rosa multiflora)
Privets (Ligustrum species)
Wineberry (Rubus phoenicolasius)
Winged burning bush (Euonymus alata)
Butterfly bush (Buddleja species)
Japanese spiraea, Japanese meadowsweet (Spiraea japonica)
Jetbead (Rhodotypos scandens)
Bradford pear (Pyrus calleryana 'Bradford')
Norway maple (Acer platanoides)
Princess tree (Paulownia tomentosa)
Tree of Heaven (Ailanthus altissima)
Silk tree, mimosa tree (Albizia julibrissin)
Paper mulberry (Broussonetia papyrifera)
Sawtooth oak (Quercus acutissima)
White mulberry (Morus alba)
English ivy (Hedera helix)
Kudzu (Pueraria montana v. lobata)
Oriental bittersweet (Celastrus orbiculatus)
Porcelainberry (Ampelopsis brevipedunculata)
Wisterias, exotic (Wisteria sinensis, W. floribunda)
Creeping euonymus (Euonymus fortunei)
Five-leaved akebia (Akebia quinata)
Japanese honeysuckle (Lonicera japonica)
Periwinkle (Vinca minor)
This is a long list but it gives you a benchmark from which to start reducing the threat from these plants.
To help stop invasives in their tracks:
· Don't disturb natural areas.
· Don't dump yard waste in or near natural areas - it may contain seeds of invasive plants.
· When you shop for garden plants skip the invasive exotic species.
· Remove invasive plants entirely or manage them to prevent spreading (such as cutting off flower heads or seeds). We are already doing that with our butterfly bushes.
· Offer to assist in exotic plant removal projects from public property.
· And most important of all, don't add these plants to your landscape.
For information on eradicating these plants go on the Web to Google.com and type in "exotic plant eradication Maryland" or write Maryland Native Plant Society P.O. Box 4877; Silver Spring, MD 20914.