This was described by Mohlenbrock & Schwegman (1969) from s. Ill. It is locally common in lowland woods on seasonally wet, fertile clayey soils of the central Mississippi and lower Ohio Valleys; see also McKinney et al. (2000). C. socialis can easily be confused with radiata or rosea, and is probably more widespread than colls. indicate. Its perigynia are similar to radiata but more elongated (L/W = 3-5 versus 1.5-3); its largest leaves tend to be wider (1.5-2.2 mm versus 1.3-1.9); and it produces conspicuous rhizomes up to 6 cm long (versus more or less cespitose). Hybrids have been suspected but not confirmed; 2n = 58 in both species (FNA 23).