Very similar to C. diandrus, differing mainly as follows: Leaves
and involucral bracts 0.5-2 mm wide. Scales of the spikelets closely
overlapping, with the achenes usually completely hidden between them, 1.8-2.2
mm long, strongly pigmented (or some lacking pigment or only partially pigmented)
with purplish-brown on the sides of the scales, usually darker toward the base,
the green keel containing the nerves; styles bifid, exserted less than
1 mm, deciduous, undivided in the lower 1/3. Late Jul--Sep. Sandy or muddy shores,
stream banks and other wet places; uncommon in se ND, scattered s to NE where
frequent; (ME and Que. to ND, s to GA, TX and s to S. Amer.; rare in w U.S.).
C. rivularis Kunth