Grandma Lake Wetlands State Natural Area is a protected wetland in Wisconsin's Nicolet National Forest, centered on an undeveloped 44-acre lake formed in a depression from the last glacial period. Around the lake, an open sphagnum bog mat is surrounded by a coniferous swamp of tamarack and black spruce, creating a layered habitat with a diverse and unusual plant community. Rare species found here include bog arrow-grass, dragon's mouth orchid, livid sedge, and one of Wisconsin's few known populations of bog rush. Its ecological value has been recognized through designation as a U.S. Forest Service Research Natural Area and inclusion among the state's Wetland Gems.