This is the first in a series of articles about “exotic” plants – that is, plants that evolved over the past thousands (perhaps, millions) of years outside of a given geographical or ecological region. Plants considered exotic in Minnesota may include those originating in other parts of the US, Europe, Asia, or other countries. Exotic plants may be intentionally brought to Minnesota by the horticulture, aquarium, or other industries. Or they may have arrived here unintentionally as “hitchhikers.” Regardless of how they were transported to Minnesota, exotic plants leave behind insects and diseases that naturally controlled their population. Unchecked by natural controls in their new environment, these plants may become invasive – or not. In reality, most exotic plants do not become invasive (e.g., tulips, marigolds), but those that do share one or more of the following characteristics:

1. tolerance to a wide range of environmental conditions
2. reproduction early, often, in large numbers, and multiple ways
3. rapid growth
4. resistance to control efforts.

Invasions of exotic plants can be disastrous – displacing native plants, which are important sources of food and shelter for wildlife and fisheries. Invasive aquatic plants can change water chemistry and flow, impede navigation, and hinder recreation. Unfortunately, once they enter into an ecosystem it is often impossible to eradicate them.

Water Hyacinth and Yellow Iris.

Invasive exotic plants are recognized and regulated at the federal, state, and county levels - making it confusing for residents and nurseries to know just what plants they may grow, where they may be grown, and where they may be distributed. Plants on the Federal Noxious Weed List (e.g., kudzu) may not legally be sold, purchased, exchanged, or received into or through the US. Within Minnesota, the Department of Natural Resources and Department of Agriculture are responsible for regulating aquatic and terrestrial plants, respectively.

Aquatic plants on the Minnesota Prohibited Exotic Species List (e.g., purple loosestrife, Eurasian water milfoil) may not be possessed, imported, purchased, sold, propagated, transported or introduced within our state boundaries. In addition, plants that pose a moderate threat to natural waters and wetlands in our state are on the list of Minnesota Regulated Exotic Species. These regulated plants (e.g., yellow iris and water hyacinth) are legal to buy and possess, but it is illegal to place them in public waters or ponds that connect to public waters. Minnesota Department of Agriculture regulates the sales, importation, transportation, and/or occurrence noxious (exotic and native) terrestrial plants and seeds. They have several categories of state plant restrictions: Prohibited Noxious Weed, Prohibited Weed Seed, Restricted Noxious Weed, Restricted Weed Seed; as well as a County Noxious Weed category.

Whether transported unintentionally by wind, animals, water, vehicles or humans or are sold through catalog and Internet sales, these species are finding their way into and around our state. Future articles will discuss these plants in more detail – how they are spread, how to identify them, what you can do to minimize the risk of introduction and impact of these plants on our natural environment, and who to contact for further information.

Posted in Plants |