Physiognomy and Structure: Trees are absent or sparse in these wetlands. A patchy to dense cover of shrubs typically 1-2 m tall may be present. The herb layer is well-developed and graminoid-dominated. Sedge or moss peat forms the substrate.

Floristics: Associations in this group may be shrub-dominated, a mixture of shrubs and herbs, or herb-dominated. Characteristic species include the shrubs Dasiphora fruticosa ssp. floribunda, Cornus amomum, Cornus racemosa, Cornus sericea, prairie grasses such as Andropogon gerardii and Spartina pectinata, sedges including Carex flava, Carex sterilis, Carex stricta, Carex prairea, and other graminoids such as Trichophorum alpinum. In the western part of its range, Carex lasiocarpa, Eriophorum angustifolium ssp. angustifolium (= Eriophorum polystachion), Parnassia glauca, Rhynchospora alba, Rhynchospora capillacea, Eleocharis compressa, and Symphyotrichum boreale (= Aster borealis) may be common. In parts of the range, scattered Juniperus virginiana may be present.

Dynamics:  The presence of cold, mineral-rich groundwater which promotes the formation of peat and marl is key to the formation and maintenance of this group. Where cold, mineral-rich groundwater emerges as seeps and diffuse springs, decomposition of plant matter is slowed and peat can accumulate. Marl forms under sustained flow of calcium- and magnesium-rich water. The marl occurs where the groundwater emerges and in "spring runs" where water has cut a channel through the peat. Peat accumulation tends to be thickest in the center of the fens and can form raised mounds over time. Some of these areas are kept open by grazing, and succession to heavier shrub cover may occur in the absence of disturbance. Fire can spread from surrounding upland grasslands in the prairie landscape and can help limit the spread of trees and shrubs in those areas.