Carex lupulina is a perennial sedge, 20-130 cm tall, few stems together, from long, branching rhizomes, plant bright yellow-green, sheaths at base of stem red-brown, persistent.
Leaves alternate, blades 0.4-1.5 cm wide, veins with small cross branches (septate-nodulose); uppermost, non-bract, leaf with sheath 1.5-25 cm long; inflorescence bracts leafy, elongate.
Flowers monoecious; uppermost spike male, 2-8 cm, on short stalk, female spikes 2-5, 1.5-6.5 cm long, 1.3-3 cm wide; perigynia very large, 1-2 cm long, about 0.3-0.6 cm wide, including 0.6-1 cm long beak, body inflated; achene 3-sided, longer than wide, with long twisted, persistent style; blooms and fruits June-Oct.
Wetland status: OBL.
Frequency in NYC: Infrequent.
Habitat: Wet meadows, pond edges, soil pH 6.2-7, moderately tolerant of shade and anaerobic soil, intolerant of fire, salt and drought.
Notes: Seeds eaten by many birds and small mammals, plants eaten by some mammals, roots eaten by moles (Martin et al. 1951).