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..2 Perigynia 4.0-6.3 mm long; pistillate spikes 7.5-12.9 mm wide (measured beak tip to beak tip); perigynium beaks 1.6-2.5 mm long, comprising 40-50% of the total length of the perigynium
....3 Proximal pistillate spike remote, often nearly basal; perigynia and foliage often olive or dark green; culms often arcuate or sinuous; staminate spikes on peduncles 3-28 mm
....3 Pistillate spikes contiguous or aggregated; foliage grayish or light green; perigynia grayish green to yellowish green; culms erect; staminate spikes on peduncles to 20 mm
......4 Larger pistillate spikes 10.5-13.5 (14.0) mm wide (measured beak tip to beak tip); longer perigynium beaks 2.3-3.2 mm long; [MI south to extreme s. OH and c. IN]
........5 Terminal (staminate) spike 12-21 mm long; pistillate spikes (1-) 2-5 per culm; tallest culms of a plant 2.5-5 dm tall; achenes 1.0-1.2 mm wide; [of acid situations in NJ, n. OH, n. IN, and northward]
........5 Terminal (staminate) spike (9-) 17-39 mm long; pistillate spikes 1-2 (-3) per culm; tallest culms of a plant 6.5-12.5 dm tall; achenes 1.2-1.5 mm wide; [of calcareous savannas of the Coastal Plain of NC]