Woody Invasives of the Great Lakes
The WIGL Collaborative focuses on 28 woody species that are regulated as invasive by at least one Great Lakes jurisdiction. This is your hub to learn everything you ever wanted to know about these species! Each species has its own profile showing:
- How to identify
- Native look-alikes
- Where it grows
- How it is regulated and where
- Recommended landscape alternatives
- How to control it
Common Traits of Woody Invasive Species
Every species is different, but certain traits are common among the Woody Invasives of the Great Lakes. They often:
- Grow and reach maturity quickly compared to native plants
- Produce a lot of seed each year
- Leaf out earlier in the spring and lose leaves later in the fall compared to native plants
- Rapidly colonize areas after disturbance events (flood, fire, land clearing, etc.)
- Produce seeds that are readily dispersed by birds, wildlife and people
- Reproduce from the root system
- Form dense, single-species stands
- Regrow after stem damage if roots are left intact
- Are adapted to a broad range of soil and light conditions
- Display high genetic variability
- Live in close association with humans
Origins and Use in Landscaping
Another thing the woody invasives plants of the Great Lakes have in common is that almost all of them were originally brought to North America intentionally as landscape plants. Usually, they were introduced at least a hundred years ago, long before the concept of invasive species was developed and before anyone was aware of the potential harm to native biodiversity. Some species (e.g., winged burning bush and porcelain berry) were introduced for use in urban and suburban gardens. Other species (e.g., white poplar and autumn olive) were introduced for more utilitarian reasons such as preventing erosion on farm fields and highway embankments. A few species have been used extensively in both garden and working land settings (e.g., Japanese honeysuckle, border privet).
Some of the woody invasive species covered by the WIGL Collaborative are still marketed today for use in landscaping. Japanese barberry, winged burning bush, Norway maple, and Callery pear are very popular because they are, for the most part, attractive, adaptable to almost any condition, and easy to grow. However, popular opinion towards these species may slowly be changing as they gain notice for invading roadsides, forest edges, and sometimes even high quality natural areas. Sometimes, if a species is causing (or is likely to cause) a lot of damage to the environment, to the economy, or to other social interests, state legislatures or regulatory agencies will enact laws or regulations to prohibit the species from being sold.
Woody Invasive Species Profile Contents and Sources of Information
The plain English name that is used most frequently in the Great Lakes region. However, you say “tomayto,” I say “tomahto,” and somebody else says “marinara plant!” This is why scientific names are important (see next item).
The Latin name by which the plant species is known. It is a two part name where the first part is the genus name and the second part names the species. Species of the same genus are closely related to each other (e.g., WIGL species Elaeagnus umbellata and Elaeagnus angustifolia – autumn and Russian olives). Sometimes, closely related species can interbreed with each other and produce hybrids (e.g., WIGL species Lonicera x bella – showy fly honeysuckle). Species will generally be known by the same scientific name by people all over the world. Exceptions occur when the taxonomy (scientific classification) of a species changes or when different classification systems are used. We have listed known synonyms too!
Each of the focal species is regulated in at least one Great Lakes jurisdiction, but some are regulated in multiple places, and sometimes these regulations are quite different. Our map tool gives an at-a-glance summary of how each species is regulated by the Great Lakes jurisdictions. See our Regulations pages for much more detail about how woody species are regulated in the region.
The species is described with special attention to characteristics that distinguish it from similar looking species. We did our best to use non-expert language, but some web searching of botanical terms may be helpful. Since a picture is worth a thousand words, we also included photos of key identifying features. Our primary references were the Manual of Woody Landscape Plants, 5th ed. by Michael A. Dirr (1998), The Morton Arboretum’s online database of tree and plant descriptions, and Missouri Botanical Garden’s online Plant Finder database. Most of our pictures came from the University of Georgia’s Center for Invasive Species and Ecosystem Health’s images database.
Describes the differences between the featured species and any close look-a-likes, with special attention to similar looking native species. Mistaken Identity – Invasive Plants and their Native Look-Alikes by Sarver et al. (2008) produced by various partners in Delaware was very helpful for these sections.
Linked resources produced by other organizations that summarize basic information on these species. Where high quality videos that help with identification of the species are available, we’ve shared those too…and where they didn’t exist already, we are making some of our own. Stay tuned!
Summary information about where in the Great Lakes region and where in North America each species is most frequently reported. Where available, we include information about the species’ cold-hardiness from the U.S. Department of Agriculture’s PLANTS database, which is an important factor (though not the only factor) influencing where a species can grow. We have also embedded distribution maps for these species from the Early Detection and Distribution Mapping System (EDDMapS). EDDMapS relies on reports of invasive species sightings from external contributors and may not give a complete picture of where a species is located. You can help get a better handle on where woody invasive species are growing! Join EDDMapS and report your sightings! EDDMapS is not the only online database used in the Midwest to report sightings of invasive species. The Midwest Invasive Species Information Network is used frequently in Michigan, and both New York and Pennsylvania use iMapInvasives. EDDMaps seems to be the furthest along in terms of integrating data across all platforms.
Describes how the species moves, both locally and over longer distances.
Describes the types of habitats, both natural and developed, where each species is most frequently found outside of cultivation.
Summary of the documented environmental, economic and health impacts caused by the species. We utilized information from Wisconsin Department of Natural Resources’ regulated invasive plant fact sheets, Minnesota Department of Agriculture’s noxious weed page, and the U.S. Forest Service’s Fire Effects Information System frequently in these sections.
Summary of how the species was historically used in landscapes and whether and how it is still used.
Summary of research on and availability of cultivated varieties (cultivars) of the species that produce less seed than the straight species.
A listing of non-invasive alternatives that share aesthetic and functional characteristics in common with the invasive species. These recommendations were generated by the WIGL Collaborative’s Landscape Alternatives subcommittee. There is a lot more information about our approach on our landscape alternatives landing page.
Photo: MichaelPortrayingLife under Creative Commons license via flickr.com