Dulichium arundinaceum is a perennial C3 sedge (Pascal-Antoine 2008), colonial from rhizomes, 30 cm to 1 m tall.
Leaves numerous, in ranks of three up stem, blade 5-15 cm long, 0.3-0.8 cm wide.
Flower spikes 1-3 cm long, spikelets linear 1-2.5 cm long, ranked along axis, scales 0.5-0.8 cm base extending down axis as wings, achene about 0.3 cm long-beaked with long persistent style; inflorescences ranked along stem in leaf axils; stalks short; blooms and fruits July-Oct.
Wetland status: OBL.
Frequency in NYC: Very infrequent.
Habitat: Open marshes, soil pH 4.7-7.5 (USDA, NRCS 2010).
Notes: Apparently formerly abundant (DeCandido 2001).