Big Swamp is a vast peatland that harbors extensive stands of muskeg, open bog, poor fen, sedge meadow, and an undeveloped seepage lake. In the southern and central portion of the site is a muskeg community with scattered, stunted black spruce and tamarack with ericaceous shrubs, sedges, and sphagnum. Jack pine is occasionally present. Characteristic species are bog rosemary, bog laurel, leather-leaf, small cranberry, black chokeberry, bog birch, bog willow, few-seeded sedge, and creeping sedge. Areas with a more dense cover of spruce support species such as Labrador tea, three-seeded sedge, tussock cotton-grass, and three-leaved Solomon's-seal. The 62-acre Clear Lake is a seepage lake containing very soft-water. Adjacent to the lake is a boggy, sphagnum lawn that features pitcher plant, arrow-grass, round-leaved sundew, and a rare orchid. Near the southern upland border, tamarack is much more dominant than spruce and is associated with alder, northern blue-flag iris, and mountain holly. The western-most section contains a gently sloping sandy peninsula that supports a dry-mesic forest dominated by red pine, red oak, and white pine. The moderately dense shrub layer is comprised primarily of beaked hazelnut. The low shrub and herbaceous layer includes early low blueberry, pipsissewa, bracken fern, Canada mayflower, American starflower, and running club-moss. Uncommon plants are early coralroot and false beech-drops. Of note are two undeveloped waterbodies that support numerous rare plants. A 22-acre seepage lake (Swanson Lake) contains extremely soft-water that supports a unique plant assemblage that is specially adapted to the infertile water. Plants include water lobelia, resupinate bladderwort, and lake quill-wort. The smaller 10-acre bog pond and wetlands supports rare plants such as hidden-fruited bladderwort and Farwell's milfoil. Avifauna includes palm warbler, black-throated green warbler, pine warbler, hermit thrush, ovenbird, winter wren, sedge wren, Lincoln's sparrow, and northern harrier. Big Swamp is owned by the DNR and was designated a State Natural Area in 2007.
