The EPA describes a wetland as “an area where naturally occurring water is at or near the surface for a significant portion of the growing season, and that, under normal conditions, supports a prevalence of vegetation typically adapted for growth in saturated soil conditions.”
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The EPA Guide,
New England Wetlands,
is an excellent guide to inland wetlands and provides identifying characteristics of the more important commonly found wetland plant species. It is the plant grouping that is the true indication of the characteristic soil conditions.
The two types of inland wetlands are bogs and marshes. After the last glacier receded some 15,000 years ago, inland wetlands formed. Marshes, typified by an absence of trees and shrubs, developed in low-lying areas which had a high water table. Bogs were formed when the retreating glacier left blocks of ice surrounded by glacial debris. As the ice melted, it left depressions called kettle-holes in the land. These depressions were later filled with meltwaters. The bog formed as sphagnum plants grew, floating upon the surface. As the floating mat became more dense, a greater variety of plants were supported and islands formed.
Figure 2 depicts a cross-section of a typical freshwater marsh. Plants in the marsh can be grouped into three categories based on degree of tolerance of wet conditions. Species which are termed tolerant are species of trees, shrubs and herbs which can grow under saturated conditions for a limited time during their growth season but do not require saturated soils for normal growth. These species can equally be found in upland dry conditions. An example of a tolerant tree in the freshwater marsh is the red maple; a tolerant woody shrub is the laurel; and a tolerant herbaceous plant is purple loosestrife. Table 1 shows tolerant, phreatophytic and hydrophilic trees, shrubs and herbaceous plants of the Connecticut area.
