Cyperus filicinus is an annual C4 sedge (Li et al. 1999), stems tufted, 10-40 cm long, slender, soft.
Leaves alternate, 0.1-0.3 cm wide, shorter than flowering stem.
Flowers dry, tiny, no petals or sepals, stamens 2, each flower covered by a straw-color, shiny, narrow scale, about 0.3 cm long; flowers crowded in ranks along spikes 1.5-2 cm long, 0.3 cm wide, very flat, stalkless or stalks (rays) to 10 cm long, inflorescence often of a dense radiating cluster of spikes, subtended by several leaf-like bracts to 25 cm long, 0.1-0.3 cm wide.
Fruit dry, 1-seeded achene, lens shaped, brownish.
Wetland status: OBL.
Frequency in NYC: Very infrequent.
Habitat: Brackish marshes, beaches, in wet hollows.