Herbs, perennial, cespitose or not, rhizomatous. Culms solitary or not, trigonous or terete. Leaves basal and cauline; cauline leaves sometimes bladeless sheaths; ligules present; blades filiform to flat with filiform tip, to 25 cm × 2.5-4 mm. Inflorescences terminal, spikelets solitary, erect or (1-)2-10(-30) in subcapitate or subumbellate panicle; involucral bracts 1-several, scalelike or blade-bearing and leaflike throughout. Spikelets: scales (10-)20-200, spirally arranged, each subtending flower, or proximal empty. Flowers bisexual; perianth persistent, of (8-)10-25 hairlike, smooth bristles, or very rarely 6 antrorsely barbed bristles, greatly elongate, essentially straight, usually obscuring most of scales in spikelet, much longer than achene; stamens 1-3; styles deciduous, linear, 3-fid. Achenes trigonous. In some species the North American populations are considered to be conspecific with Eurasian populations; differences in achene micromorphology and isozyme data suggest that these relationships should be investigated more thoroughly.