Eleocharis palustris is a perennial C3 spikerush (Pascal-Antoine 2008), 10 cm to 1 m tall, colonial from rhizomes, stems more or less solitary;
Leaves bladeless, sheaths only. leaf sheath oblique at top.
Flower spike narrow, 0.5-4 cm, brown, lance to egg-shaped, 1-3 empty scale at base; fertile scales 0.2-0.4 cm long
Fruit a dry achene, lens-shaped to bluntly 3-sided, widest above middle, yellow-brown when mature, 0.1-0.2 cm, tubercle wide, constricted at base, style 2-parted, anthers 0.1-0.25 cm.
Wetland status: OBL.
Frequency in NYC: Very infrequent.
Habitat: Along edges of ponds, open wet meadows and roadsides, moderately tolerant of fire, intolerant of salt and shade, soil pH 4-8 (USDA, NRCS 2010).