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First let's understand what a native (indigenous) plant is. Every species of plant, animal, fungi, bacteria and other organism has a home in some part of the world, where it has existed for thousands of years as a result of natural forces and influences like climate, storms, moisture, fire, soils and species interactions. Over long periods of time, these and other physical and biological factors direct the distributions of organisms in nature. A native species is one that occurs in a particular region, ecosystem, and habitat without the influence of human actions.

I'll begin explaining what an invasive plant is by jogging your memories of your American History classes. I'm sure we all remember learning about the British invasion and America's fight for independence. Well, those first ships that brought human colonists to North America, and the ensuing (pursuing) British, also brought along a few plant colonists. The plant colonists were much like the human colonists; some of them had good traits, caused no problems and blended right in with the new American culture. Others were of bad character, got into everything, and generally became a nuisance to society. And, like the human colonists, the British did not uproot them; they remained long after the war subsided. Comparing plant to human colonists may seem a bit silly, but it is actually how "invasive" or "non-native" plants became established in North America.

Invasive plants are plants that have been introduced into an environment in which they did not evolve and thus usually have no natural enemies to limit their reproduction and spread. Being able to survive outside of their natural environment doesn't automatically qualify them as "invasive." They earn that title by competing aggressively with native species to the point of displacing them. Invasive plants normally exhibit strong vegetative growth, abundant seed production, high seed germination rate, long-lived seeds, and rapid maturation to a seed-producing stage.

Why worry about invasive plants?

No matter where you live, on a farm, in the suburbs, or in a high-rise apartment building, non-native plants will have some affect on your life. How so?

Well, you experience the impact of these plants daily and probably don't realize it. The price you pay for groceries at the market reflects the farmer's costs of weed (aka invasive plants) control. Farmers continually fight the battle of controlling invasive plants because they reduce yields, interfere with harvesting operations, and reduce the quality of their crops. Low quality crops in turn results in low quality products on your grocer's shelves. Agricultural losses and control costs due to invasive plants are estimated at $15 billion per year in the U.S.

Invasive plants interfere with recreational activities in parks, refuges, forests, grasslands, and other natural areas. Since such lands are usually maintained by public agencies, costs associated with invasive plant management are passed on to you in the form of higher taxes or fees.

There is a long-term threat to biodiversity (all life on earth, even that which has yet to be discovered), ecosystem stability, and the balance of nature on which all species depend, associated with invasive plants. Each alien plant is one less native host plant for our native insects, vertebrates and other organisms that are dependent upon them. Population biology indicates that ecosystems can eventually evolve back toward diversity - by developing species that thrive by eating or competing with the invasives - however, there may be irretrievable species lost in the interim.

Some invasive plants have earned the distinction of noxious. This is a legal designation and is used specifically for plant species that have been determined to be major pests of agricultural ecosystems and are subject, by law, to certain restrictions. The U.S. Department of Agriculture regulates noxious weeds.

Are invasive plants found in Indiana?

Unfortunately, yes. Of the roughly 2,300 plant species growing outside of cultivation in Indiana, 25% are nonnative The following are some examples of species found here (those with a designation have made the top ten, most damaging, list in Indiana):

	Crown Vetch (Coronilla varia)You will often see crown vetch growing on steep hillsides beside the highway. At one time, it was often planted for erosion control since it is fast growing, and, as a member of the pea family, its roots shelter nitrogen-fixing bacteria, which nourish the soil. However, it's roots are actually quite weak, and its dense foliage prevents other plants from taking root, bringing about worse erosion problems in the long run. Moreover, because it out-competes most native plants, resource managers now regard it as a noxious weed.
Kudzu (Pueraria montana var. lobata) A high-climbing perennial vine from eastern Asia, kudzu has alternate leaves and deep purple, pealike flowers. The deep fleshy roots of the plant survive the mild winters of the south, although the vines do not, and resprout each spring with vigor. In the early 1900s, kudzu was grown as a forage crop, to reduce erosion, and to improve the soil. At one point, the federal government paid farmers up to $8 per acre to plant kudzu. Given its ability to grow as much as a foot a day during the summer, kudzu eventually "ate the south" and was demoted to a common weed by the U.S. Department of Agriculture in 1970.
	Multiflora Rose (Rosa multiflora) is a thorny, perennial shrub brought from Japan in 1866 as rootstock for ornamental roses. It is extremely prolific and can form impenetrable thickets. These qualities prompted the U.S. Soil Conservation Service to promote the rose in the 1930s as a "living fence" to confine livestock. It was also valued as wildlife cover and as food for songbirds. The aggressive growth habits of multiflora rose were eventually recognized as a problem on pastures and unplowed land where it disrupted cattle grazing and displaced many native plant species. It is now classified as a noxious weed in several states.
Purple loosestrife (Lyghrum salicaria) is a perennial herb that grows best in freshwater marshes, open stream margins, and alluvial floodplains. It was introduced to the United States in the 1800s as a wetland landscape plant. It was also favored by beekeepers because of its nectar-producing ability. However, this highly prolific plant has infested much of the wetlands found in the U.S. and threatens endangered, threatened, and declining plant and animal species. It has been declared a noxious weed in many states, but it still sold in nurseries for perennial gardens.
	Johnsongrass (Sorghum halepense) is a perennial grass. It was originally introduced into the United States as a forage crop in the early 1800s. Johnsongrass freely hybridizes with grain sorghum under field conditions. The hybrids can be fertile and exhibit no apparent decrease in fitness. However, when the hybrid plant freezes, it develops a toxin that can be fatal to grazing cattle. Cut hay and silage from fields infested with johnsongrass must be cured for six weeks before being used to ensure the toxin has degraded.
Japanese Honeysuckle (Lonicera japonica), a native of eastern Asia, is a trailing or twining woody vine that can grow to more than 30 feet in length. Its fragrant flowers are produced throughout the summer. Vines can grow in dense shade, however, when provided with increased light levels, grow rapidly and spread. Therefore, areas of natural or human disturbance such as logging, road building, floods, windstorms, or pest and disease outbreaks, are often invaded by the plant. The dense, strangling growth of Japanese honeysuckle impacts desirable vegetation by decreasing available light, depleting soil moisture and nutrients, or by toppling upright stems through the sheer weight of accumulated vines.
	Dandelion *(Taraxacum officinale)* The dreaded companion of urban landscapes, the dandelion was introduced to the United States in the 1600s by European colonists who cultivated it in their gardens for food and medicine. As we all know, it is no longer valued for those uses, and is now no more than a common weed. Its tough taproot anchors the plant securely and makes it difficult to eradicate. Gardens, fields, pastures, waysides and waste places, all provide excellent habitat for dandelions.
Other Invasive Plants Found In Indiana (It should be noted that some of these are still commonly available in nurseries!) Buckthorn (Rhamnus cathartica, R. frangula) Bush Honeysuckle (Lonicera maackii, L. tatarica, L. morrowii) Garlic Mustard (Alliaria petiolata) Autumn Olive (Elaeagnus umbellata) Reed Canary Grass (Phalaris arundinacea) Oriental Bitterseweet (Celastrus orbiculatus) Common Reed or Phragmites (Phragmites australis) Flowers Canada thistle (Cirsium arvense) Dame's rocket (Hesperis matronalis) Sericea lespedeza (Lespedeza cuneata) Sweet clover (Melilotus alba, M. officinalis) Star of Bethlehem (Ornithogalum umbellatum) Japanese knotweed (Polygonum cuspidatum) Grasses Smoothe brome (Bromus inermis) Tall fescue (Festuca elatior) Japanese stilt grass (Microstegium vimineum) Maiden grass (Miscanthus sinensis) Vines and Groundcovers Purple winter creeper (Euonymus fortunei) Creeping Charlie (Glechoma hederacea) Japanese hops (Humulus japonicus) Creeping Jenny (Lysimachia nummularia) Periwinkle (Vinca minor) Shrubs Black alder (Alnus glutinosa) Winged burning bush (Euonymus alatus) Bicolor lespedeza (Lespedeza bicolor) Common privet (Ligustrum vulgare) Highbush cranberry (Viburnum opulus v. opulus) Trees Norway maple (Acer platanoides) Tree of heaven (Ailanthus altissima) White mulberry (Morus alba) Black locust (Robinia pseudoacacia) Siberian elm (Ulmus pumila)

What can be done to control invasive plants?

As they say, prevention is the best medicine, and so it is with the control of invasive plants. To prevent the introduction or spread of invasive plants, and to help restore native flora and faunas, you can:

Avoid disturbance to natural areas.
Exclude invasive exotic species from your landscaping, land restoration, or erosion control projects. Seek plants that are native to your local region as much as possible or those that are not known to be invasive. (Nurseries should be able to help you with selecting alternatives.)
Become familiar with the plants on your property. If you are unsure of the identification of a plant, take a sample to a university, arboretum, department of agriculture office, or local nature center for assistance.
Control exotic invasive plants in your landscape by removing them entirely or by managing them to prevent their spread. This may involve pruning to prevent flowering and seed dispersal, or cutting, mowing or herbicides use to prevent vegetative spread.
Alert people in your neighborhood and place of work about the problem with invasives and what species to watch for. Encourage nurseries and garden shops in your area not to sell these species.
Assist in local exotic plant removal projects.