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..2 Leaves 0.3-0.8 mm wide, filiform-involute; ligules 0.3-0.8 (-1.2) mm long; inflorescences 14-32 mm long; spikes 2-3 per inflorescence; terminal spike with 1-3 perigynia per spike; [south to PA and s. NJ]
..2 Leaves 0.8-1.9 mm wide, flat or thinly M-shaped; ligules 0.5-1.9 mm long; inflorescences (14-) 23-55 mm long; spikes (2-) 3-4 per inflorescence; terminal spike with (1-) 2-6 perigynia per spike; [south to w. NC]
....3 Perigynia broadest near the base of the body, with a conspicuous beak 0.7-1.1 mm long; spikes mostly 7-15, usually ± overlapping or crowded into an ovoid narrowly pyramidal head 2-4.5 cm long
......4 Perigynia 5-10 (-15) per spike; perigynium without ventral nerves (or the nerves very obscure); spike at maturity somewhat bristly appearing in silhouette because of the perigynium beaks
........5 Culms 15-60 cm tall; inflorescence 3-5 (-7) cm long, all but the lowest spikes approximate, the lowest spikes 0.5-2.5 cm apart
........5 Culms 30-90 cm tall; inflorescences 6-12 (-15) cm long, the lower and middle spikes well-spaced, the lowest spikes 2-5 cm apart