This variable species occurs in diverse types of seasonally wet habitat, mostly from the northern Great Plains to the North Atlantic Coast. In Ky. it is largely restricted to marshy places on some riverbanks. It is known from Tenn. along a railroad close to TODD (APSC). The few records away from rivers suggest that, before settlement, it might have been more widespread. See also notes under Panicum virgatum, which has similar distribution but extends onto drier sites; both species are tolerant of eutrophic conditions (e.g. Belt 2015). Both species have cytological variation that needs more research; 2n = 40 to 94 in S. pectinata (FNA 25). Combination of Spartina with Sporobolus is supported by molecular evidence (W). Morphological distinction is largely dependant on inflorescence; in Spartina the. inflorescence is an array of spikes, the spikelets closely imbricate in 2 rows along the rachis of the spikes, the spikes alternate along the primary inflorescence axis; in most traditional Sporobolus of North America (including Calamovilfa), the inflorescence is a slender or broad panicle (W).