Similar to S. acutus; culms rather stout near the base, terete,
1-3.5 m long, light green, easily crushed when fresh. Leaves consisting
of 4-5 basal sheaths, the upper ones with a blade to 7 cm long; principal
involucral bract erect, 1.5-11 cm long. Inflorescence a panicle of
up to 235 spikelets, appearing lateral, spreading, rarely congested, lax and
drooping; spikelets solitary or paired on the pedicels, rarely in glomerules
of 3 or more, reddish-brown, 4-13 mm long, 3-4 mm thick; scales suffused
with reddish-brown to dark brown, 1.8-3.2 mm long, scarious, often very finely
ciliate on the margins, obtuse or rounded, usually mucronate, the mucro to 0.5
mm long; perianth of 6 bristles, mostly equaling or exceeding the achene
body; stamens 3; styles bifid. Achenes light green to dark
brown or black, lenticular, unequally biconvex, the body 1.5-2.1 mm long, 1.3-1.6
mm wide, the beak minute, to 0.2 mm long. Jun--mid Aug. Same habitats as S.
acutus but mostly in fresh water and more often in riparian and stream habitats;
common, often abundant; (Newf. to s AK, s to S.Amer.). S. validus Vahl