Provides general resources to help identify unknown species that may be invasive. Species identification is important in helping gardeners, land managers, and landscape architects identify invasive species that can be harmful to local habitats. Resources are organized alphabetically by organization.

An important caveat is it can be difficult to identify species properly on the Internet. If you are unable to identify the species in question, you may want to contact your county Extension office and work with Extension personnel to obtain assistance from an area agent or state specialist (select state to see state pest detection contacts). Or, you may want to use the Ask an Expert feature of Invasive Species - eXtension.

See other sections for species specific information:

• General
• Aquatic Species
  • Aquatic Animals
  • Aquatic Plants
• Plants
• Animals
• Microbes

General

North American Invasive Identification Guide and Checklist and IDnature Guides
University of Georgia. Discover Life.

Landscape Problem Solver
University of Maryland. Maryland Cooperative Extension.
Identifies plant pests, including insects and diseases. Includes information and instructions for submitting plant or insect samples (PDF | 70 KB).

Identification Aids & Services
USDA. Animal and Plant Health Inspection Service.

Identification Technology Program (ITP) - Digital Identification Tools
USDA. APHIS. Plant Protection and Quarantine.
"ITP supports PPQ in its efforts to prevent the entry, spread, and establishment of invasive pests in the U.S. by delivering interactive, electronic identification tools."

Diseases, Pests and Weeds
USDA. ARS. National Agricultural Library.

Aquatic Species

Marine Invasive Species Identification Guide for the Puget Sound Area: Puget Sound Marine Invasive Species Volunteer Monitoring Program (MISM) (Jul 2009; PDF | 1 MB)
Puget Sound Partnership (Washington).

Aquatic Animals

Identifying Michigan Fish (including Snakehead)
Michigan Department of Natural Resources and Environment.

Brief Guide to Crayfish Identification in the Pacific Northwest (2009; PDF | 440 KB)
University of Washington. School of Aquatic and Fishery Science.

Fish Identification - Resource for Researching Fish of Wisconsin
University of Wisconsin Center of Limnology; Wisconsin Sea Grant; Wisconsin Department of Natural Resources.

Identify Your Fish
Wisconsin Sea Grant.

Aquatic Plants

Connecticut's Invasive Aquatic and Wetlands Plants Identification Guide (2010; PDF | 8.4 MB)
Connecticut Agricultural Experiment Station.
Bulletin No. 1027.

Aquatic Invasive Plant Identification Guide
River to River Cooperative Weed Management Area (Illinois).

A Field Guide to Invasive Plants of Aquatic and Wetland Habitats for Michigan (2010; PDF | 4.2 MB)
Michigan State University Extension.

Identifying Aquatic Weeds
Mississippi State University Extension Service.
Includes information for how to submit a sample.

Help with Aquatic Plant Identification
New Hampshire Department of Environmental Services.

Plant Identification - AQUAPLANT
Texas A&M University. Department of Wildlife and Fisheries Sciences.
"AQUAPLANT is designed to help you identify aquatic plants using photos, drawings, and descriptions. Using this section involves viewing photos and drawings of aquatic plants until you identify the plant in question."

Aquatic Weed Identification Flow Chart (PDF | 234 KB)
King County (Washington).

Plants

What Tree Is That? Tree Identification Field Guide
Arbor Day Foundation.

Identification Key to Weeds
University of California at Davis. Statewide Integrated Pest Management Program.

Weed Identification Tool
University of California. Cooperative Extension and Agricultural Experiment Station.

Colorado Noxious Weed Identification Key
Colorado State University. Adams County.
"Residents of Adams County are welcome to call, email, or bring a plant sample to the Extension office for identification."

Weed Identification Tool
Colorado Weed Management Association.

Leafsnap: An Electronic Field Guide
Columbia University; University of Maryland; Smithsonian Institution.
Tree identification mobile app using visual recognition software to help identify tree species from photographs on their leaves.

Hawaii's Invasive Plant Species: A Noxious Weed Identification Key
Hawaii Biological Survey.

University of Illinois Plant Clinic
University of Illinois at Urbana-Champaign. Extension.
"Provides plant and insect identification, diagnosis of plant disease, insect, weed and chemical injury (chemical injury on field crops only)."

Weed Identification
University of Illinois at Urbana-Champaign. Illinois Council on Food and Agricultural Research.

Identifying Weeds in Field Crops
Michigan State University. Integrated Pest Management Program.

Weed ID Tool
Michigan State University. Department of Crop and Soil Sciences.

Plant Finder
Missouri Botanical Garden.
"The Kemper Garden Center at the Missouri Botanical Garden has pictures, plant information, and sources for many natives that are in the horticultural trade. You can search by scientific or common name. Through their PlantFinder Search options you can also search by preferred habitat, growth form, use (water plant, attracts butterflies, dried flowers, etc), and other characteristics, like good fall color."

Missouri Plants
MissouriPlants.com.
"Provides photographs, descriptions, and keys to the flowering and non-flowering plants of Missouri. This site has a brief key you can click on based on flower color and leaf arrangement. You can scan through images to find the plant you are looking for. The individual plant pages have descriptions and details illustrated by beautiful close-up photos of plant parts like leaves and stems, often showing the range of variation that can be found in a single individual."

Mistaken Identity? Invasive Plants and their Native Look-alikes: an Identification Guide for the Mid-Atlantic (Nov 2008; PDF | 7 MB)
New York Botanical Garden.
Published by the Delaware Department of Agriculture in collaboration with Claude E. Phillips Herbarium at Delaware. State University and Delaware Center for Horticulture
"This publication is a full-color, 62-page booklet. The purpose of the work is to facilitate correct identification of confusingly similar invasive and native plant species. Targeted at land managers, gardeners, conservationists, and all others interested in plants, this booklet covers over 20 invasive species and their native look-alikes."

Exotic Thistle Identification Key
University of Nebraska - Kearney.

Turf & Weed Identification
North Carolina State University. Center for Turfgrass Environmental Research & Education.

Ask Mr. Smarty Plants
University of Texas at Austin. Lady Bird Johnson Wildflower Center.

Grass Weed Identification Guide
Virginia Polytechnic Institute and State University.

Learn to Identify Plants
USDA. ARS. National Agricultural Library.

PLANTS Interactive ID Keys and The PLANTS Database
USDA. Natural Resources Conservation Service. National Plant Data Center.

Plant Identification Tools and Guides
USDA. Natural Resources Conservation Service.

Weed Identification Help
King County (Washington).

Weed Identification Tool
University of Wisconsin.
"The database contains 280 of the most common weeds/invasive plants found in agricultural, urban, and natural settings in Wisconsin. The database is organized to ask questions about the unknown plant, and, based on the user's input, the website will produce a list of plants (scientific and common names) along with thumbnail images that match the information entered."

Animals

Arthropod Identification
American Museum of Natural History.

Amphibian and Reptile Identification
University of Florida. Department of Wildlife Ecology and Conservation.

Wildlife Damage Inspection Decision Tree
Internet Center for Wildlife Damage Management.

Microbes

Diagnosing Tree Disorders
Colorado State University. Extension.

Plant Disease Diagnostic Clinic
Cornell University.

Common Tree Diseases of British Columbia
Natural Resources Canada. Pacific Forestry Centre.

Tree Diseases by Signs and Symptoms
Natural Resources Canada. Canadian Forest Service.
Note: Archived content.

Diagnostic Keys to Major Tree Fruit Diseases in the Mid-Atlantic Region
West Virginia University - Kearneysville.
"The diagnostic keys for deciduous tree fruit diseases (apple, peach, nectarine, and cherry) were developed to aid field personnel in the identification of diseases that are common to the mid-Atlantic region of the United States."