L., Sp. Pl. 46.1753
C. ferax L.
Annual, usually (10) 50-100 cm tall. Leaves linear, (1.5) 5-14 mm wide. Bracts subtending inflorescence large and leaflike, mostly 15-50 cm long; inflorescences compound (rarely simple), the racemes sessile or on short to long rays (to 20 cm long); spikelets linear, subterete, mostly 7-22 mm long, brownish at maturity; scales 2-3 mm long, striate, ± divergent in age; rachilla strongly winged, the wings becoming corky in age, the spikelets breaking up into single segments. Achenes oblong, 1.5-2 .7 mm long, weakly trigonous, dark brown, densely papillose. Croat 9563, 13239.
An occasional weed of clearings and marshes. Flowers throughout most of the year.
Well-developed or fruiting specimens are not confused with any other species. Depauperate epiphytic plants on floating logs in the lake may be only 10-25 cm tall and with leaves 1.5-2.5 mm wide. These specimens have a simple inflorescence, but may be distinguished from C. tenuis by having corky rachilla wings.
Tropics and subtropics throughout the world. In Panama, known principally from tropical moist forest in the Canal Zone, Bocas del Toro, San Blas, Los Santos, Panama, and Darien; known also from tropical dry forest in Coclé, from premontane moist forest in Panama, from premontane wet forest in Veraguas and Panama, from tropical wet forest in Colón, and from lower montane wet forest in Chiriqui.