At the extreme southern tip of Illinois, the land flattens and is poorly drained. Southern flora is present in this area, the northernmost extent of the coastal plain that stretches to the Gulf of Mexico. Swamps, dominated by bald cypress (some of the largest and oldest trees in Illinois) and tupelo, are reminiscent of Louisiana bayous. The Heron Pond-Little Black Slough Nature Preserve is a significant natural area with high-quality swamp and floodplain forest as well as upland forest and glade communities.

SIZE: 443,616 acres; 693 square miles

LOCATION: Southern Illinois along the Cache River; Alexander, Johnson, Massac, Pulaski, and Union counties.

The Cache River RRA is located at the southern tip of Illinois. The upper reach flows through the hills of the Ozark plateau; the lower Cache flows through flatter coastal plain where drainage is slow and wetlands become more abundant. Unique features include bald cypress-tupelo gum swamps and several species associated with the southern U.S. The Cache River RRA shares a common border with the Illinois Ozarks RRA; the large, contiguous forests that occur along the boundary are split into the two RRAs.

Significant natural features that represent forest, wetland, and aquatic habitats are found at Horseshoe Lake, an old oxbow of the Mississippi River. Near-virgin woods of beech, sugar maple, swamp chestnut oak, and American elm grow on the island in the middle of the lake. Bald cypress, tupelo, swamp cottonwood, willow, and buttonbush are found in the shallow water. Several interesting and rare species are known from here, including the spotted gar, pugnose minnow, green treefrog, mole salamander, broad-banded water snake, green water snake, prothonotary warbler, red-shouldered hawk, big-eared bat, and rice rat.

The green treefrog is one of the most colorful frogs in North America. Its bright green-to-olive coloration protects it from predators as it perches on vegetation in swamps, floodplain sloughs, and marshes. In Illinois, the green treefrog is limited to the extreme southern tip of the state.

LANDCOVER : The landcover is fairly evenly divided among three categories--cropland (32%), grassland (29%), and upland woods (27%). In terms of percentage of the site, the Cache River RRA ranks fourth for grassland, fifth for upland woods, and sixth for bottomland woods. This site has the eighth highest acreage of nonforested wetlands.

NATURAL AREAS : Sixty-three Natural Areas totalling 18,444 acres are located in this RRA. This RRA ranks third in number of Natural Areas and fourth in acreage of Natural Areas. Significant features include caves, springs, barrens, ponds, lakes, swamps, woods, and geological features. The largest Natural Areas are Heron Pond-Little Black Slough (6,613 acres) and the Lower Cache River Swamp (6,561 acres).

BIOLOGICALLY SIGNIFICANT STREAMS : Six stream segments totalling 53 miles have been designated as BSS. Horseshoe Lake and Lake Creek support a number of species that are extremely rare in Illinois.

HERITAGE SITES : There are 298 Heritage occurrences, the second highest number among the RRAs. There are 17 community types, 41 plant species, and 43 animal species represented. Seven large forest tracts and two rookeries are located here.

STATE AND FEDERAL LAND : The total acreage of public land in this RRA is 65,665 acres, or 15% of the land area. There are three state parks and two state conservation areas. The majority of public land is federally owned and consists of Cypress Creek National Wildlife Refuge and Shawnee National Forest.

NATURE PRESERVES : Eight Nature Preserves are located in the Cache River RRA. Principal natural features include glades, upland forests, floodplain forests, bluffs, ravines, ponds, and cypress-tupelo swamps.

NATURAL DIVISIONS : The Natural Divisions of the Cache River RRA are the Coastal Plain (58%), Shawnee Hills (35%), and Ozarks (7%).