Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Genus Description - Spikelets in pairs, or at the ends of the branches in threes, numerous, dorsally compressed, forming a large, branching panicle that in wild- adapted plants disarticulates at maturity into joints bearing a single pair (or trio) of spikelets; one spikelet of each pair sessile and perfect, the other pedicellate and staminate or neuter; glumes indurate, about equal; lemmas hyaline, the palea ± reduced, both sorts of spikelets typically with a lower empty lemma and an upper floriferous one; upper lemma of the fertile spikelet usually with a geniculate and twisted, readily deciduous dorsal awn. 20, e. Afr., s. Asia, and Aust.