(L.) Vahl, Enum. Pl. 2:287.1805
F. annua (Allioni) R. & S.; F. diphylla (Retz.) Vahl
Annual or perennial, nearly glabrous, 5-60 cm tall; culms terete, leafy near base. Leaves linear, ca 3 mm wide,
mostly arising from base of culm, the margins scabrous. Inflorescences branched, usually loose and open, subtended by few bracts, the bracts longer than inflorescence; spikelets numerous, 5-10 mm long, solitary on peduncles, acute, brownish; scales having a green keel and minute apiculum; flowers perfect; stamens 1-3; style bifid, prominently fimbriate. Achenes obovate, terete, ca 1 mm long, white to brown, with a minute projection at base, sculptured with both vertical grooves and transverse wrinkles. Croat 8566.
Common in clearings. Flowers throughout the year, principally in the rainy season.
Low altitudes in temperate and tropical areas of the world. In Panama, known principally from tropical moist forest in the Canal Zone, Bocas del Toro, Colón, Herrera, Panama, and Darién; known also from tropical dry forest in Coclé and Panama (Taboga Island), from premontane moist forest in the Canal Zone and Panama, from premontane wet forest in Chiriqui and Coclé, from tropical wet forest in Colón, and from lower montane wet forest in Chiriqui.