Dwarf and tufted to tall and solitary annual 5-60 cm tall, the culms usually
stout and erect. Leaves usually not surpassing the culms, the blades
1-4 mm wide; involucral bracts often much better developed than the leaves,
to 8 mm wide, usually much exceeding the inflorescence. Spikelets pinnately
disposed on a more or less elongate rachis to form several rather open cylindrical
spikes; rays 1-6 cm long; spikelets 8-20 mm long; scales not overlapping
in the spikelets, the tip of each not reaching the base of the scale directly
above it (on the same side of the rachilla), 2-2.5 mm long, golden brown to
brown, finely several-nerved toward the middle of the back; rachilla
winged, clasping the achenes, disarticulating between the scales and falling
in 1-fruited segments at maturity; stamens 3; styles trifid. Achenes
brown, trigonous, linear-oblong, 1-1.5 mm long. Late Jul--Sep. Sandy or muddy
shores and stream banks; locally common in ne SD and the n Sand Hills, otherwise
rare; (MA to ND, s to VA and MO; widespread in tropical and warm temperate regions
of the New World).