LU 



GO 



Q (Anacharis canadensis), naiads (Najas spp.), coontail (Ceratophyllum 



< demersum), and water milfoil {Myriophyllum spp.). In the South, water 



hyacinth (Eichornia crassipes) often forms a dense surface mat. 



OPEN FRESH WATER (F-5-M). This includes natural shallow 

 ponds, springs, and man-made impoundments usually less than 10 ft in 

 depth. These are widespread, but most abundant in Florida and the 

 prairie pothole country of the north-central United States, where they 

 are noted for their high waterfowl production. The vegetation of the 

 marginal zone is dominated by emergent vegetation (see F-3-M); the 

 deeper areas by floating and submerged aquatics (see F-4-M). Species 

 of the prairie potholes include cattails, bulrushes, spikerushes, smart- 

 weeds, and whitetop. 



SHRUB SWAMPS (F-6-Ss) (sometimes referred to as Carrs). The 

 water-table is at or near the surface throughout much of the year, and 

 they may be flooded with as much as 6-12 inches of water at certain 

 periods. Such swamps occur throughout the deciduous forest region in 

 upland depressions and along rivers and sluggish streams. They are 

 especially common in the Lake States and Florida. The vegetation in- 

 cludes willows (Salix spp.), alders (Alnus spp.), buttonbush 

 (Cephalanthus occidentalis), dogwoods (Cornus spp.), viburnums 

 (Viburnum spp.), sweet pepperbush (Clethra alnifolia), and swamp 

 privet (Forestiera acuminata). 



WOODED SWAMPS (F-7-Sw). The water table is at or near the 

 surface throughout the year and 6-12 inches of standing water during 

 part of the year is common. They occur in poorly drained upland sites 

 along streams, shallow river basins, and deltas. The vegetation includes 

 the typical red maple-hardwood swamps of the Northeast and the vast 

 acreage of bottom-land hardwoods and cypress swamps of the 

 Southeast. Wooded swamps are also frequent in the Lake States. The 

 Great Cypress Swamp of west Florida is one of the most extensive of 

 such areas in North America. Although river flood-plain swamp forests 

 intergrade with seasonally flooded swamp forests (F-l-Sw), those more 

 continuously flooded throughout the year are included here. Shrub and 

 wooded swamp types may also intergrade. Forest composition varies 

 geographically. In the Northeast: red maple (Acer rubrum), black ash 

 (Fraxinus nigra), black spruce (Picea mariana), balsam fir (Abies bal- 

 samea), black gum (Nyssa sylvatica), tamarack (Lari.x laricina), and 

 arbor vitae (Thuja occidentalis). In the Southeast: primary trees are 

 cypress (Taxodium spp.), water oak (Quercus nigra), overcup oak 

 (Quercus lyrata), swamp black gum (Nyssa biflora), tupelo gum (Nyssa 

 aquatica), and pond pine (Pinus rigida var. serotina). In the Northwest: 

 western hemlock (Tsuga heterophylla), red alder (Alnus rubra), and 

 willows (Salix spp.). 



BOGS (F-8-B). These usually develop in deep lakes and poorly 

 drained depressions of glacial origin, and are underlain by extensive 

 peat deposits. They occur throughout the glaciated regions of the 



