Knowledge about the plants in an area is essential for delineating wetlands. Wetlands normally contain distinctly different kinds of plants than those found in uplands. Correctly identifying the most common plants is an important first step in recognizing wetlands.

Wetlands have water at, or near the surface, of the land for some period during the vegetative growing season. Because of the presence of water, wetlands will experience some time periods when there is little or no oxygen in the soils.  Wetland plants have adaptations or responses that allow them to survive, grow, and reproduce with their roots in water or saturated soils for at least part of a year.  Conversely, many plants cannot survive in saturated conditions and are commonly referred to as upland plants. 

On a relatively undisturbed site, plants can be one of the best ways to identify wetland areas. If they are predominantly wetland plant types, the area is very likely to be a wetland. People skilled in identifying plants can use a reference that will help determine whether or not the predominant plants on a site indicate the presence of a wetland.

The National List of Plant Species That Occur in Wetlands: Michigan by Porter B. Reed, Jr. identifies and classifies wetland plants. In addition to giving the names of wetland plants, it includes information about how commonly each plant occurs in wetlands (some wetland plants can also survive in uplands and vice versa) and other useful information. The system classifies wetland plants as to their affinity or tolerance to growing in wetlands. Plants are classified as follows:

If greater than 50% of the plants at a site are Facultative (FAC) or wetter (OBL or FACW), then the site meets the wetland vegetation criteria.

There are several limitations to using this reference. The most critical is that you must have correctly identified the plants to the species level. Simply knowing that a tree is an oak will not work unless you know precisely which species it is. Also, the list will not help unless it is used to classify the predominant plants in the vegetative community. Using less common plants may give an inaccurate picture of the area. Therefore, one must first determine which plants are the most common and then apply the plant list to those species. Reliance on common names is risky. Some plants have more than one common name and sometimes different plants are known by the same name. Just because you may not find a plant listed under the name you know it by does not mean that it is not somewhere else on the list. Finally, it must be realized that the plant community is only an indicator of the presence of water and may, in some cases, be misleading. This is particularly true when a site has been disturbed or planted with species that would not exist there naturally.

The following websites provide a list of plants with their indicator categories, national plant databases, and picture guides to wetland plants.

Web of Michigan Plants

National List of Wetland Plants

Midwestern Wetland Flora

Wetland Plants and Plant Communities of Minnesota and Wisconsin

USDA Plants National Database

Identifying MI Trees

MEKA Home Page

Aquatic and Wetland Plant Guides and Manuals