Erect perennial, mostly 50-100 cm tall; calms in small tufts, rarely branched., glabrous. Sheaths longer than the internodes, keeled, glabrous or sparsely pubescent; blades 15-50 cm long, 3-10 mm wide, glabrous or sparsely pilose above, scabrid on and near the margins. Inflorescence a panicle 20-30 cm long of ascending racemes; racemes often tufted at base, 2-10 cm long; spikelets plano-convex, paired, 2-2.8 mm long, on scabrid pedicels, broadly elliptic, glabrous or appressed-pubescent; first glume lacking; second glume and sterile lemma covering fruit, keeled; sterile lemma weakly cross-wrinkled near the margins. Fruits dark brown, smooth, shiny. Croat 10333. Apparently rare, though locally abundant in the Laboratory Clearing. Flowers most abundantly during the rainy season. Southern United States to Argentina; West Indies. In Panama, known from tropical moist forest in the Canal Zone, Colón, San Blas, Chiriqui, Herrera, Panama, and Darien, from tropical dry forest in Coclé and Panama, from premontane wet forest in Colón, Chiriqui, Coclé, and Panama, from tropical wet forest in Colón, and from lower montane wet forest in Chiriqui (Volcán).