Weed ID Lists by Region in North America
... the Ergonica Weed Identification Reference Matrix - EWIRM

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Over 200 weed ID lists and databases are listed and described on these pages, including information about images, costs (if any), list criteria, number of species, and authors.  They are sorted by multi-state regions followed by individual states or provinces in alphabetical order.  Most states have passed legislation to identify noxious weeds and other types of weeds that should be managed carefully.  Legislation often forbids the movement of noxious weed seed into the state.  Some weeds are classified with restricted movement in counties where the county has administrative authority. 

Several lists also identify poisonous plants and some lists include maps of the distribution of weeds in various regions.  There is a lot of interesting information on many of these lists, including the history of when and how weeds were introduced to the region, the way they are often transported, costs to agriculture and land management, and impacts on other flora and fauna.

To identify a weed in your area, we suggest you look at the lists identified for your state or province.  The lists in this website derive from regional legislation or from agricultural scientists with expertise in weed science.  Most  of the online lists include images or illustrations to help you identify your weeds.  If the online images and descriptions are not sufficient to identify a specific weed in your area, you may find many weed images by name by using Google or Yahoo! image search tools.  The images from Google and Yahoo! usually link to more information about the image content.  The Ergonica menu header above also provides convenient links to these search tools.  You may need to use these links when viewing lists with no pictures.

Most lists are free, online references with common names and images or illustrations.  All entries are linked directly to their source or location for purchase.  Your taxes most likely paid for at least part of the costs of researching the information, photographing the plants, and publishing them on the Web or in other formats.  Some lists of weeds without photos have been included in order to reveal the status or location of weeds in a given region.  If no images are provided, or you need more images in addition to Google and Yahoo! for positive identification, you may purchase a reference such as the WSSA CD-ROM 1,000 Weeds of North America, which provides a user interface to identify weeds by key features.  This CD-ROM includes an astounding collection of weeds with high quality images and plant-feature selection prompts that make it easy to identify a weed without scanning through all the images.

Several other books, pamphlets and CD-ROMs are also included that are not free.  These are useful references often with higher quality images or convenient user software to identify weeds by key features, such as flower colors and leaf size and shape.  The information on this website will help you decide whether a free list will satisfy your needs, or whether you need another reference that you can carry to the fields in a bag or laptop computer. 

Interactive Weed Identification Key Selection

To appreciate the convenience of interactive identification key software, similar to those provided by some CD-ROMs and DVDs, look at the Weed Identification web site published by the Illinois Council on Food and Agricultural Research.  Using a web form, you can select information about an unidentified weed, and compare it with photographs and text descriptions of weeds that share similar characteristics.  Keys with prompts include features of leaves, flowers, growth, ligules and life cycle.  With just a few clicks of a mouse, the database of weeds displayed on the form reduces in number from 172 to as few as one or two. 

Virginia Tech Cooperative Extension publishes the Grass Weed Identification Key.  By clicking on the "Identify Unknown Sample" button, you will be taken through a series of questions which should provide you with the identity of your unknown sample or bring you to a narrow list of potential candidates. This reference includes 44 grass-like common weeds and weed seedlings found throughout Virginia and the Southeastern U.S.  Prompted selection options include root system, leaf width, ligules, seed head, auricle, leaf type, and other plant features.  This is a good way to learn about grass identification keys.

The University of California Integrated Pest Management Program (IPM) provides a convenient Identification Key for Turfgrass which helps you identify up to 51 weeds using plant features such as broadleaf, grasses, sedges, inflorescence, leaf margin, stems, root, petiole, etc.  Each key  is illustrated and explained to help you make the right choice which involves simply clicking on an icon.  It's easy to go back and revise your selection, if necessary.  

To identify any of 21 grasses in your lawn, Purdue University provides a grass key selection system which allows you to select options for vernation, ligule, auricles, leaf tip, leaf surface, mid-rib, collar, growth and seedhead.  This Turfgrass Identification Tool is a recently (June 2005) added weed identification aid offered by Purdue.  Whether your lawn has weeds or not, it's important to know what type of grasses are in your lawn. 

BASF offers an interactive weed key selection program designed for agriculture in Canada which helps you select among 15 grassy and 27 broadleaf weeds.  The Weed ID Guide: Grassy Weeds prompts you to select among ligule features with illustrations to identify grassy weeds.  The features of cotyledons (seedling leaves) are used to differentiate between broadleaf weeds in the Weed ID Guide: Broadleaf Weeds.

The Weed Identification Key, by Colorado State University, provides a less robust interactive key system which features 15 weeds to select with the interactive identification keys.  Prompted keys to select include leaf type, leaf surface type, and leaf edge.  Although the sample of species is smaller than some others,  it serves as a good example of the convenience and ease of using interactive selection programs.  The larger the database, such as those provided on CD-ROMs and DVDs, the more keys needed for final selections.

Search by Name or Text Entry

Without plant feature selection prompts, like those above, other searchable databases allow you to type in a name or keyword related to the plant description.  For example, the FDA Poisonous Plant Database includes over 85,000 plant species references and offers a search program by name or other descriptive text.  If you enter the search term 'hemlock', for example you will get a list of over 500 records of published references that include 'hemlock' in their name or description.  The records consist of articles, reports and other published information about poisonous plants.  For a smaller selection, by entering the search term 'poison hemlock' you will see a subset of about 100 references.  The search term 'cattle grazing', for example, returns a list of around 70 references, whereas 'cattle' by itself returns more than 1000 records and requires additional definition.  The searches are conducted very efficiently, especially with regard to the large database of records.  Here you may discover that many poisonous plants are not normally identified as weeds, and some plants have edible fruit, for example, but other parts that are poisonous.

Over 8,800 images of vascular plants can be searched by name or descriptive term at the Digital Flora of Texas Vascular Plant Image Library, a service of Texas A&M University Service Projects, Bioinformatics Working Group.  Searching for 'weed', for example, returns over 90 images of 20 species of plants with 'weed' in the name or description.

Search through over 250,000 records of plant specimens by scientific name, genus or species in the Herbaria Plant Specimen Database of the Wisconsin State Herbarium.  The Wisconsin Botanical Information System (WBIS) is an online database of Wisconsin's vascular plant information and collected specimens.  Searches exclude detailed location information for endangered and threatened species.  A search for "brassica", for example, will yield a list of 124 records, most of which linked to images.

The Ohio Plant Facts search interface, formerly known as the Plant Dictionary, provides searches by name for over 1,000 ornamental plants and another 1,000 turf plants.  Weeds in these databases are not identified separately.  If you know the name, or partial name, of a plant, the images will help you verify the identification of the plant.  For the ornamental plant listings, you can also hear the pronunciation of the scientific name.

The Pennsylvania Flora Project, by the Botany Department, Morris Arboretum of the University of Pennsylvania, provides search selections with prompts by scientific or common name, introduced / native, growth habit, conservation status, wetlands indicator code, county and watershed.  The basic taxonomic file contains 3,432 records derived from nearly 400,000 herbarium specimens.  Records can be queried taxonomically or geographically.  A search of introduced species results in a list of 945 records.  Native species number 2,135.  Images are not currently available, but appear to be included in the database.

More than 750 plants with their photographs are presented on Gardentia.net.   This site gives tips on cultivation of plants and also about pests, diseases, pesticides etc.  The database can be searched by name or partial name of plants, including either botanical or common names.

You may also search by weed name for images of about 100 turf weeds throughout the USA through WeedAlert.com.  The search can also be filtered for weeds in various regions such as the Western, Southern, North Central and North East regions of the US.  This is a commercial website that generally promotes chemical solutions to turf weed control.

There are many scientists, government employees, professionals, volunteers and students who have demonstrated great expertise in compiling the lists and presenting the many images included in the EWIRM.  By examining just a few weed identification references, you will be more aware of the tremendous amount of skillful work that is devoted each year to identifying weeds and using this knowledge to protect us all from the harmful effects they cause.  Although usually fought  behind the scenes, the War on Weeds is one that impacts every region of the world.  You can play a helpful role in the ongoing War on Weeds by learning more about the identification and status of noxious weeds in your area.

~Know your weeds to control your weeds: Weed Identification Images, Names and Botanical Classifications

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Even if you don't know the name of a particular weed, by using the convenient Weed Finder Tools, you can identify a weed by selecting key features.  In a short time, by using this amazing tool, you can become the expert weed pundit in your neighborhood.

Weed ID Quiz

Ready for a Quiz on
Weed ID?

If you believe you're ready for a quiz about weed identification, try out the Weed Identification Quiz and the Poisonous Plant Quiz published by the Ontario Ministry of Agriculture and Foods.

Passed the above quizzes?  If you think you're good, here's another Weed ID Test by the Westside Gardener.

On a roll?  Purdue University has some questions for you in Weed ID Practice Quiz I and Quiz II.

Utah State University would like to quiz you on 10 weeds that you should be able to identify.

Now, to get your Weed Expert Degree, try your skills on the Seed ID Quizzes by Ohio State Department of Horticulture and Crop Science.

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