Spring Wetland Vegetation

In early spring, when temperatures are still cool at night and daylight hours are just starting to lengthen, most plants are just starting to become active.  Many amphibian and bird species also start their breeding activities at this time of year, and some of those depend on wetlands for egg laying sites, nesting material, food, and protection.  Wetland vegetation creates important habitat for these species.

Emergent plants are non-woody species that are rooted in wetland bottoms, but grow tall and emerge above the surface of the water.  There are three categories of emergent plants that are important to pond life, including narrow-leaved emergents, broad-leaved emergents, and tall-robust emergents.  Additional plants that affect wildlife populations in wetlands include floating plants, shrubs and trees.

Narrow-leaved emergent plants are grasslike, with narrow stems and leaves, and grow to less than six feet in height.  They come from the plant families that include sedges, Carex; rushes, Juncus; and bulrushes, Scripus.  Some common narrow-leaved emergents of northern Illinois are common bur reed, Sparganium eurycarpum; horsetail, Equisetum arvense; reed canary grass, Phalaris arundinacea; and blue-joint grass, Calamagrostis canadensis.  They provide cover for tadpoles and stems for perching birds to call from.  Underwater stems are used to anchor frog egg sacs, and above surface leaves are used for egg laying by several species of dragonflies and damselflies.

Broad-leaved emergent plants are characterized by leaves almost as wide as they are long, and they grow to under three feet in height.  Common species in northern Illinois include marsh smartweed, Persicaria amphibia stipulacea; common beggar’s ticks, Bidens frondosa; and water willow, Justicia americana.  With broader leaves, these species provide excellent protection for adult and juvenile amphibians.

Tall-robust emergent plants are 5′ to 9′ tall when mature.  Leaf and stem sizes vary greatly.  In winter, some of the plants may die back or collapse, but many species grow in tightly packed stands where portions of the plant group will survive the entire winter.  Examples in northern Illinois include narrow-leaved cattail, Typha angustifolia and broad-leaved cattail, Typha latifolia.   In addition, common reed, Phragmites australis, is a highly invasive species found throughout our area.

Two other groups of plants are important to early spring wildlife.  Shrubs, woody plants from 3′ to 9′ tall,  and trees, woody plants over 9′ tall.  Growing on wetland banks or in shallow water, trees and shrubs have branches and leaves that may be submerged or growing just above the surface.  These provide perches for calling species, and some may be used for egg-laying sites.  Common species in our area include blue-fruited dogwood, Cornus obliqua; silver maple, Acer saccharinum; and buttonbush, Cephelanthus occidentalis.  Floating plants only grow on the surface where there is several inches of water.  They are good indicators of water depth and the extent of open water in wetlands.  They provide cover for many underwater eggs and juveniles.  Duckweeds of the Lemna family and pond lilies in the Nuphar and Nymphaea families are common floating plants in this area.

Wetlands with emergent vegetation and stable water levels provide healthy habitat for bird, insect, and amphibian breeding populations.  As you are out walking this spring, be sure to look at wetland vegetation and how it is used by the wildlife populations living there.