Typical muhlenbergii is a widespread eastern species, typical of thin woods and brushy grassland on dry acid soils, often with sandy substrates (F, FNA 23). The closely related species, cephalaphora, often occurs in adjacent woods. C. muhlenbergii differs in its less densely aggregated spikes, with internodes usually evident between them, and the whole inflorescence generally more elongated (mostly 1.5-4 cm long versus 0.5-2 cm); also, plants tend to be taller (up to 9 dm versus 6 dm), with narrower leaves (up to 2-4 mm wide versus 2.5-5 mm) and more exserted inflorescence. Variation in overall robustness, pistillate scale size or shape (acute to cuspidate), and perigynium size or shape need deeper study in Ky. Records mapped here are probably accurate to species, but only tentative to variety. More robust specimens of grassy woods and openings have been referred by some collectors to the southwestern species, austrina, or to the northwestern species, gravida (M), but most of these have been redetermined as muhlenbergii by A. Reznicek, R. Naczi, L. McKinney or others. There has also been confusion with aggregata; see notes under var. enervis. Spelling as "muehlenbergii" is incorrect according to R. Naczi (pers. comm.), despite its use in FNA 23.