1 Pistillate scales uniformly as long as or longer than the mature perigynia, usually concealing the beaks (though not necessarily the bodies), apex obtuse to acuminate, not awned.

  2 Perigynium beak cylindric, unwinged, lacking serrations for ca. 0.4 mm below the apex

  2 Perigynium beak flattened, ciliate-serrulate all the way to the apex.

    3 Pistillate scales as wide as and essentially covering perigynia bodies

    3 Pistillate scales usually distinctly narrower than perigynia bodies.

      4 Principal leaves stiff, more-or-less glaucous, often bearing auricles at the base, the summit of the sheaths truncate, prolonged 1-4 mm beyond the collar; flat margins of perigynia 0.5-0.8 mm wide; achenes 1.0-1.2 mm wide; [of maritime dunes and shores]

      4 Principal leaves pliable, green, almost always without auricles, the summit of the sheaths U-shaped, only slightly prolonged beyond the collar; flat margins of perigynia 0.2-0.6 mm wide; achenes 1.0-1.7 mm wide; [of inland, non-maritime habitats].

        5 Perigynia ascending to spreading, strongly and evenly veined on the adaxial face, finely granular-papillose; spikes (3-) 7-15, the uppermost usually densely aggregated

        5 Perigynia erect-ascending, often veinless on the adaxial face or with a few veins of unequal strength, smooth; spikes 3-7 (-11), the uppermost often more-or-less separated

1 Pistillate scales (excluding the awns, if present) shorter than the perigynia at least in the middle portions of the spikes, the apical portion of the pistillate scales narrower than the perigynia beaks and not completely covering them, the apex awned in some species.

          6 Pistillate scales in middle or lower portions of spikes with apex acuminate with subulate or awned tip.

             7 Perigynia 2.6-4.0× as long as wide, the bodies lanceolate, 1.2-2.0 mm wide

               8 Perigynia 0.9-1.2 mm wide; achenes 0.6-0.8 mm wide; inflorescences dense, the lowermost internode 2-3 (-5) mm long

               8 Perigynia 1.2-2 mm wide; achenes 0.7-1.1 mm wide; inflorescences dense to open, the lowermost internode 2-17 mm long.

                 9 Inflorescences nodding or flexuous, spikes well separated; pistillate scales acute; perigynia spreading

                 9 Inflorescences dense or open, spikes usually overlapping; pistillate scales acuminate; perigynia usually ascending

             7 Perigynia < 2.5× as long as wide, the bodies lance-ovate, ovate, broadly elliptic, orbiculate, or obovate, 1.8-3.9 mm wide.

                   10 Perigynia (5.8-) 6.0-7.1 mm at longest; perigynium beak 2-2.8 mm long; pistillate scales with apex white-hyaline, acuminate-awned, fragile, membranaceous, and often curled, midvein not extending to tip

                   10 Perigynia (2.3-) 2.5-5.9 (-6.3) mm at longest; perigynium beak 0.85-2.2 (-2.5) mm long; pistillate scales with apex firm, greenish to reddish brown, straight, midvein extending to tip.

                     11 Perigynium body obovate, often with conspicuous “shoulders”; leaves 2.5-6 mm at widest

                     11 Perigynium body elliptic, suborbiculate, or weakly obovate; leaves 1-3 (-4.2) mm at widest.

                       12 Perigynium body cuneately tapered to the base, the body of the perigynium more-or-less diamond-shaped; inflorescences dense, stiffly erect, with 3-5 spikes

                       12 Perigynium body convexly tapered to the base (the base rounded), the body of the perigynium ovate, elliptic, orbiculate, or weakly obovate; inflorescences dense and erect or open and nodding, with 3-11 spikes.

                          13 Scales with white-hyaline or pale yellowish margins; perigynia greenish to straw-colored or pale brown, (2.3-) 2.5-4.0 (-4.2) mm long, often indistinctly 0-4 (-6) veined on the outer side

                          13 Scales with reddish-brown margins; perigynia reddish-brown, (3.8-) 4.0-5.5 mm long, conspicuously veined on the outer side with 5 or more veins.

                            14 Beaks ascending, < ½ the length of the lance-ovate to weakly obovate perigynium body; lateral spikes with acute staminate bases mostly < 2 mm long; [of tidal marshes]

                            14 Beaks widely spreading, > ½ the length of the suborbicular perigynium body; lateral spikes with tapered staminate bases 2-6 mm long; [of freshwater wetlands]

          6 Pistillate scales with apex obtuse, acute, or acuminate (but not subulate or awned).

                              15 Perigynia < 2 mm wide.

                                16 Perigynia thin, often not winged to the base; leaf sheaths somewhat expanded toward the apex, bearing narrow wings continuous with the midvein and the edges of the leaf blade; leaves 3-7.5 mm wide; vegetative shoots tall, conspicuous, with numerous leaves spaced along the upper half of the culm.

                                  17 Lower perigynia of each spike spreading or recurved (at an angle of > 80 degrees); spikes globose; pistillate scales hidden, 1.6-2.3 mm long

                                  17 Lower perigynia of each spike appressed-ascending to somewhat spreading (at a 30-75 degree angle); spikes subglobose to ovate-oblong; pistillate scales evident, 2.0-3.0 mm long.

                                    18 Inflorescences usually flexible, nodding at the tip, the lower spikes usually separated; perigynia usually 15-40, spreading at a 40-75 degree angle to the spike axis; leaf sheaths firm or friable at the summit

                                    18 Inflorescences straight and stiff, the lower spikes overlapping; perigynia usually > 40, appressed-ascending at a 30-40 degree angle to the spike axis; leaf sheaths firm at the summit.

                                       19 Perigynia 3.0-4.0 mm long, 2.2-2.8 (-3) × as long as wide

                                       19 Perigynia (3.3-) 3.6-5.4 mm long, 3-5 × as long as wide

                                16 Perigynia thick, winged to the base; leaf sheaths with more-or-less rounded edges, not distinctly expanded toward the apex; leaves 1-4.5 mm wide (except in C. normalis); vegetative shoots usually inconspicuous, with relatively few leaves clustered at the tip.

                                         20 Perigynia (2.5-) 2.6-4 × as long as wide, the body lanceolate, distance from beak tip to top of achene 2.2-5 mm

                                           21 Perigynia 0.9-1.2 mm wide; achenes 0.6-0.8 mm wide; inflorescences dense, the lowermost internode 2-3 (-5) mm long

                                           21 Perigynia 1.2-2 mm wide; achenes 0.7-1.1 mm wide; inflorescences dense to open, the lowermost internode 2-17 mm long.

                                             22 Inflorescences nodding or flexuous, spikes well separated; pistillate scales acute; perigynia spreading

                                             22 Inflorescences dense or open, spikes usually overlapping; pistillate scales acuminate; perigynia usually ascending

                                         20 Perigynia < 2.5 × as long as wide, the body obovate, orbiculate, or ovate; distance from beak tip to top of achene 0.8-2.2 mm.

                                               23 Perigynium body obovate, widest toward the tip (excluding the beak).

                                                 24 Perigynium beak spreading, slender; pistillate scales acute; styles sinuous at base

                                                 24 Perigynium beak appressed-ascending, triangular; pistillate scales obtuse; styles straight

                                               23 Perigynium body ovate, elliptic, or orbiculate, widest toward the base or near the middle (excluding the beak).

                                                    25 Inflorescences on tallest culms compact, 1.5-3 × as long as wide, erect, the spikes overlapping, the lowest internode of the inflorescence 1-6 (-7.5) mm, ½ to 1/5 (-¼) the length of the inflorescence

                                                      26 Achenes 0.6-0.9 mm wide; perigynia veinless or 1-3 veined on the inner face, these faint or basal only; inflorescences < 3.0 cm long

                                                      26 Achenes 0.9-1.3 mm wide; perigynia often 3-veined on the inner face; inflorescences 12-60 mm long.

                                                        27 Perigynia broadly elliptic or nearly orbiculate, the wing margin 0.4-0.8 mm wide, 0-6 veined on the inner face

                                                        27 Perigynia ovate to broadly ovate, the wing margin 0.25-0.45 mm wide, 4-7 veined on the inner face

                                                    25 Inflorescences on tallest culms elongate, more-or-less open toward the base, (2.5-) 3.0-5.1 × as long as wide, often arching or nodding at the tip; spikes more-or-less separate; lowermost internode (5-) 7-19 mm long, mostly 1/5-1/3 (-1/2) the length of the inflorescence.

                                                          28 Perigynium orbiculate, widest at mid-body

                                                          28 Perigynium narrowly to broadly ovate, widest below mid-body.

                                                            29 Sheaths smooth, often whitish-mottled; perigynium beak spreading, exceeding the pistillate scales by 0.7-1.6 mm; beak and shoulders of perigynia greenish to yellowish or greenish brown at maturity

                                                            29 Sheaths, at least some, papillose near the collar (at magnification of 30 ×), not prominently whitish-mottled; perigynium beak appressed or ascending in spikes, exceeding the pistillate scales by 0.0-0.8 mm; beak and shoulders of perigynia straw-colored to reddish-brown at maturity

                              15 Perigynia > 2 mm wide.

                                                              30 Spikes 12-28 mm long, with tapered base and acute tip; perigynium body lanceolate, 6-9 mm long; vegetative culms conspicuous

                                                              30 Spikes either shorter than 12 mm or longer and with either rounded bases or tips or both; perigynium body ovate, elliptic, orbicular, or obovate, or lanceolate (if lanceolate, then shorter than 6 mm long); vegetative culms conspicuous or not.

                                                                 31 Perigynium bodies obovate, widest toward the tip; leaf sheaths green-veined adaxially nearly to the summit, or with a narrow Y-shaped hyaline area.

                                                                   32 Achenes 1.3-1.8 mm wide

                                                                     33 Perigynia (5.6-) 6.0-7.1 × 3.3-4.6 (-4.8) mm, exceeding the subtending scale by 1.5-2.6 mm; staminate and proximal pistillate scales obtuse to acute; pistillate scales 2.4-3.2 (-3.4)× as long as wide

                                                                     33 Perigynia (4.5-) 4.8-6.0 (-6.3) × 2.5-3.8 mm, exceeding the subtending scale by (0.4-) 0.6-1.4 (-1.6) mm; staminate and proximal pistillate scales acuminate; pistillate scales (2.6-) 2.9-3.7 (-4.2)× as long as wide

                                                                   32 Achenes 0.75-1.2 (-1.3) mm wide.

                                                                       34 Inflorescences arching or nodding, 2.3-8.4 cm long; spikes widely separated.

                                                                         35 Sheaths smooth, summits concave, only reaching base of leaf blade; pistillate scales yellowish to reddish brown; [Interior Highlands and adjacent provinces, AR, LA, OK, and ne. TX]

                                                                         35 Sheaths finely papillose (use at least 30× magnification), summits truncate, prolonged 1-4 mm beyond collar; pistillate scales white-hyaline; [coastal, south to e. VA]

                                                                       34 Inflorescences erect, 1-4.5 cm long; spikes slightly separated to congested.

                                                                           36 Perigynium beak spreading, slender; pistillate scales acute; styles sinuous at base

                                                                           36 Perigynium beak appressed-ascending, triangular; pistillate scales obtuse; styles straight.

                                                                              37 Perigynia veinless on adaxial face; leaves 3-6 (-8) mm at widest; sheaths truncate at summit and extending 0.3 mm beyond collar

                                                                              37 Perigynia veined on adaxial face; leaves 2-4 (-4.5) mm at widest; sheaths concave at summit and not prolonged beyond collar.

                                                                                38 Pistillate scales white-hyaline to pale silvery-brown, obtuse; achenes 0.7-1 mm wide; achene apiculum < 0.4 mm long; [widespread]

                                                                                38 Pistillate scales reddish brown, acute; achenes 0.9-1.2 mm wide; achene apiculum 0.4-0.8 mm long; [Interior Highlands and adjacent areas]

                                                                 31 Perigynium bodies lanceolate, ovate, elliptic, orbicular, or reniform, widest at the middle or toward the base; leaf sheaths various, some with prominent hyaline band near the apex adaxially.

                                                                                  39 Plants colonial, from creeping rhizomes; vegetative culms numerous, conspicuous, strongly 3-ranked, with 15-35 leaves when fully-developed; achenes 1.6-2 × as long as wide; larger spikes with 5-25 (-30) perigynia

                                                                                  39 Plants clumping; vegetative culms few, inconspicuous, usually with fewer than 15 leaves, not strikingly 3-ranked; achenes 1-1.6 (-1.7) × as long as wide; larger spikes with 15-80 perigynia.

                                                                                    40 Perigynia finely granular-papillose (as seen with 30× magnification), the body reniform to orbiculate, 0.6-0.9 ×as long as wide, 3.5-4.5 (-4.9) mm wide; lowermost pistillate scale obtuse-rounded

                                                                                    40 Perigynia smooth, the body broadly ovate, elliptic, orbicular, or slightly obovate, (0.7-) 0.9-1.7 × as long as wide, 1.5-6.1 mm wide; lowermost pistillate scales obtuse to acuminate-awned.

                                                                                      41 Perigynia 5.5-8.0 (-8.7) × (3.1-) 3.3-6.3 mm at largest (except sometimes in C. bicknellii and C. shinnersii), often prominently bulged on both faces; beak (1.4-) 1.6-2.5 (-3.4) mm long.

                                                                                        42 Perigynia (2.5-) 2.7-4.8 mm at widest, (0-) 1-8-veined over achene adaxially; staminate and pistillate scales obtuse to acuminate-awned, midvein not excurrent as scabrous awn; larger culms with (3-) 4-7 (-11) spikes.

                                                                                           43 Leaf sheaths finely papillose, at least near apex; perigynia membranaceous, with brown achene clearly visible through hyaline adaxial face, usually with reddish brown tinged wings, strongly, evenly 4-8-veined adaxially over achene; pistillate scales usually reddish brown; anthers (2.4-)2.8-4.2 mm; plants in small clumps (usually fewer than 25 culms) in dry to mesic habitats

                                                                                           43 Leaf sheaths smooth; perigynia herbaceous, opaque, with achene not clearly visible through adaxial face, with greenish or pale brown wings, finely and irregularly (0-)1-7-veined over achene adaxially; pistillate scales pale yellowish brown to brown; anthers (1.8-)2.2-3.6 mm; plants often in dense, large clumps (to 200 culms) in wet habitats.

                                                                                             44 Staminate and pistillate scales acuminate-awned, tip white to brownish hyaline, membranaceous, often ± curled, midvein fading before tip; beak of larger perigynia 2.0-2.6 (-2.8) mm long; perigynium body (1.3-) 1.4-2.1× as long as the beak

                                                                                             44 Staminate and pistillate scales obtuse to acuminate, tip firm, herbaceous, flat or inrolled, midvein prominent to tip; beak (1.2-) 1.5-2.1 (-2.3) mm long; perigynium body 1.9-3× as long as the beak

                                                                                      41 Perigynia 2.5-5.5 × 2.0-3.6 mm at largest (to 6.1 × 4.4 mm in the Florida endemic C. vexans), prominently bulged by achene only on abaxial face or flat; beak usually 0.7-1.6 (-1.8) mm long.

                                                                                               45 Leaf sheaths green-veined adaxially nearly to the summit; inflorescences dense to somewhat open, erect, the lowermost internode usually < 8 (-12) mm long

                                                                                                 46 Perigynia with acute bases, 2.0-2.8 mm wide; beak appressed, > 2/5 × the length of the body; broadest leaves 1.5-2.5 mm wide; [of sw. VA northward]

                                                                                                 46 Perigynia with rounded bases, 3.0-4.4 mm wide; beak spreading, ca. ⅓ × the length of the body; broadest leaves 2-5 mm wide; [of FL]

                                                                                               45 Leaf sheaths with white-hyaline area adaxially; inflorescences open or dense.

                                                                                                   47 Perigynium body narrowly to broadly ovate, greenish; pistillate scales with green midstripe, hyaline or pale margins (rarely brown tinged); leaves 2.5-6.5 mm wide, the sheaths green mottled, with mouth truncate, and prolonged to 2 mm distal to base of the leaf blades

                                                                                                   47 Perigynium body broadly ovate, broadly elliptic, or orbiculate, yellowish to tan brown; pistillate scales greenish or dark brown; leaves 1.5-4 (-5) mm wide, the sheaths usually evenly colored, with mouth concave.

                                                                                                     48 Leaf sheaths finely papillose (at magnification of 30-40 ×), especially near the leaf base.

                                                                                                        49 Perigynia strongly and evenly 4-8-veined over the achene adaxially, (4.5-) 5.1-5.5 mm long; pistillate scales usually (1.0-) 1.4-2.3 mm shorter than the perigynia; anthers (2.4-) 2.8-4.2 mm long

                                                                                                        49 Perigynia veinless or faintly and irregularly 0-4 (-6)-veined over the achene adaxially, 2.5-4.2 mm long; pistillate scales 0.2-1.3 mm shorter than the perigynia; anthers 1.0-2.1 mm long

                                                                                                          50 Perigynia 2.3-3.5 mm wide; distance from summit of achene to tip of beak 1.8-3.1 mm; achenes 1.1-1.5 mm wide; spike apex rounded or nearly acute; [Long Island west to n. OH and s. WI, northward]

                                                                                                          50 Perigynia 1.5-2.3(-2.5) mm wide; distance from summit of achene to tip of beak 0.8-1.7(-2) mm; achenes 1-1.3 mm wide; spike apex rounded; [widespread throughout eastern and midwestern US]

                                                                                                     48 Leaf sheaths smooth.

                                                                                                            51 Spikes on larger culms (3-) 5-7 (-11), tapered at the base, the terminal spike with a conspicuous staminate base; inflorescences typically open, 2.5-4.5 (-6.5) cm long, the lowermost internode (3-) 4-13 (-23) mm long; perigynium body (0.7-) 0.9-1.3 × as long as wide.

                                                                                                              52 Achenes 1.2-1.8 mm long, 1.0-1.3 mm wide; perigynia 2.5-4.2 mm long, 1.5-2.3 (-2.5) mm wide, mostly 2-4 (-6)-veined adaxially

                                                                                                              52 Achenes (1.6-) 1.7-2.2 mm long, (1.2-) 1.4-1.8 mm wide; perigynia 3.2-5.5 mm long, 2.5-3.6 mm wide, veinless or faintly 1-5 (-7)-veined adaxially.

                                                                                                                53 Perigynia 3.2-4.8 (-5.2) mm long; beak 0.8-1.5 mm long; pistillate scales 3.3-4.0 (-4.3) mm long, acute; achenes 1.0-1.3 (1.4) × as long as wide

                                                                                                                53 Perigynia (5.6-) 6.0-7.1 mm long; beak (1.2-) 1.5-2.1 (-2.3) mm long; pistillate scales (3.6-) 3.9-5.0 mm long, obtuse to acute

                                                                                                            51 Spikes on larger culms 2-4 (-5), rounded at the base, the terminal spike usually lacking a conspicuous staminate base; inflorescences compact, 1.2-3.0 (-3.6) cm long, the lowermost internode 1.5-7 (-13) mm long; perigynium body (0.7-) 0.9-1.6 × as long as wide.

                                                                                                                  54 Achenes of larger perigynia ellipsoid to narrowly oblong, 0.9-1.3 mm wide, 1.3-1.6 × as long as wide; perigynia (25-) 30-80 per spike, squarrose-spreading at maturity, 1.8-3.0 mm wide

                                                                                                                  54 Achenes of larger perigynia broadly oblong to nearly orbicular, 1.35-1.8 mm wide, 1-1.3 × as long as wide; perigynia (10-) 15-40 (-45) per spike, appressed-ascending at maturity, (2.1-) 2.5-3.4 (-3.5) mm wide.

                                                                                                                     55 Perigynia veinless or faintly and irregularly 1-5-veined over the achene adaxially, more-or-less orbicular, the bodies (2-) 2.3-3.2 mm long, (0.7-) 0.9-1.1 (-1.3) × as long as wide; pistillate scales mostly acute, about as long as to 0.7 (-0.9) mm shorter than the subtended perigynium (flattened and measured separately)

                                                                                                                     55 Perigynia strongly 4-6-veined over the achene adaxially, broadly ovate to broadly elliptic, (or rarely nearly orbicular), the bodies (2.7-) 3-4 mm long, (0.9-) 1.0-1.6 × as long as wide; pistillate scales mostly obtuse, 0.7-1.7 mm shorter than the subtended perigynium (flattened and measured separately)