This is widespread from mid-western to east-central states, but rare to absent in most southeastern states (FNA, 8; K, W). It occurs mostly in thin woods and edges on moist, well-drained fertile soils (K, W; FNA 8). It is close to amphibola and corrugata (FNA 23), and there has been much confusion (e.g. Cr). C. grisea differs from both those species in its longer achene bodies at maturity (2.6-3.7 mm versus 1.8-2.4 mm) on relatively short stipes (mostly 0.3-0.4 mm versus 0.4-0.6 mm). Compared to amphibola, the perigynia of grisea are usually wider (1.8-2.6 mm versus 1.5-2.2 mm), less elongated (L/W = 1.8-2.3 versus 2.5-3.1), and more rounded in cross-section. Compared to corrugata, its pergynia are longer (mostly 4.5-5.1 mm versus 3.9-4.5 mm) but with similar L/W ratio. C. grisea is a relatively robust species of section Griseae, with culms usually reaching 15-90 cm long and occasionally up to 120 cm (as cultivated in garden of JC); corrugata reaches similar lengths, but amphibola tends to be shorter (15-80 cm).