Variation within this largely midwestern, somewhat weedy (but often overlooked) species needs careful attention; 2n = 68 or 70. Although generally accepted as distinct (FNA 23), it has been confused with other species, and there has been some suggestion of hybrid origin (Gl, Cr). Several colls. referred here to molesta have relatively elongated inflorescences or narrow perigynia (resembling normalis), in contrast to older published descriptions. In Ky. molesta or molestiformis are locally common on uplands with damp or compacted clay soils, especially in old pastures or hayfields of the Bluegrass region (often associated with C. aggregata), whereas normalis occurs in more mesic, shady habitats (often associated with C. sparganioides). C. molesta, molestiformis and brevior appear closely related; see notes under brevior. However, their general distinction from festucacea, normalis and other relatives is not simple (FNA 23, W), with generally larger achenes, larger perigynia and more congested inflorescences, often with few spikes. Compared to normalis, molesta has perigynia that tend to be relatively broad (elliptic to suborbicular versus ovate), with wider marginal wings (0.4-0.8 mm versus 0.25-0.45 mm); they become pale brown when mature, as do the scales (versus remaining green and white), and adaxial surfaces have less distinct veins (0-6 versus 4-7). In inflorescences, proximal internodes are mostly 1.5-6 mm long (versus 3.5-10 mm); leaves tend to have narrower blades (ca. 1.5-4 mm versus 2.5-6 mm); sheaths are more uniformly greenish to stramineous (versus slightly mottled with green veins), and have concave summits (versus truncate).