1 Primary culm accompanied by pistillate spikes borne on short or elongate peduncles from the same sheathed base (referred to as subradical or basal spikes).

..2 Terminal staminate spikes alone or associated with a pistillate spike; lower pistillate scales acuminate, mostly exceeding the perigynium beak; perigynia lacking discernible papillae.

....3 Perigynia (2.2-) 2.3-3.2 (-3.3) mm long; perigynium beaks (0.4-) 0.5-0.9 mm long; young leaves long, thin and flexuous

....3 Perigynia (3.0-) 3.1-4.7 mm long; perigynium beaks (0.9-) 1.0-2.1 mm long; young leaves variable.

......4 Perigynium body essentially glabrous, with a few hairs on the angles of the beak only; young leaves short, broad and rigid

..2 Terminal staminate spikes usually with at least one approximate pistillate spike; lower pistillate scales acute, mostly shorter than the perigynium beak; perigynia distinctly papillate, at least at the base of the beak (except C. deflexa).

........5 Staminate spikes 3.2-5.6 mm long; perigynia with broadly deltoid beaks, coarse spreading trichomes, and indiscernible papillae; basal spikes 0-1 (-2)

........5 Staminate spikes 3.6-16.8 mm long; perigynia with narrow beaks, finer spreading trichomes, and papillae evident; basal spikes 1-2 (-3).

..........6 Perigynium body elliptic, with adaxial and abaxial surfaces lacking hairs (some often present on angles of the beak only), papillae prominent; [se. Coastal Plain]

..........6 Perigynium body round-elliptic, with adaxial and abaxial surfaces pubescent, papillae concentrated mostly below the beak; [ne. North America and southern Appalachians].

............ 7 Staminate spikes large, 6.8-16.8 × 1.0-2.9 mm, exceeding adjacent pistillate spikes by 4.7-16.5 mm, peduncles 3.5-13.5 mm long; culm bracts setaceous, 0.1-0.3 mm wide, and mostly shorter than the inflorescence.

............ ..8 Culms much shorter than longest seasonal (green) leaf; primary culms with 0-1 (very rarely 2) pistillate spikes; staminate spikes 6.8-11.0 × 1.0-1.7 mm; adaxial perigynium body with spreading hairs; [ultramafic fens of nw. NC & sw. VA]

............ ..8 Culms subequal to exceeding longest seasonal (green) leaf; primary culms with 1-2 pistillate spikes; staminate spikes 8.0-16.8 × 1.0-2.9 mm; adaxial perigynium body with fine sub-appressed hairs; [granitic seepages; escarpment of nw. NC mountains]

............ 7 Staminate spikes smaller, 3.6-9.0 × 0.7-1.5 mm, exceeding adjacent pistillate spikes by 1.3-8.9 mm, peduncles 0.9-3.9 mm long; culm bracts broad or setaceous, 0.3-0.8 mm wide, shorter than to exceeding the inflorescence.

............ ....9 Primary culms to 20.2 cm tall; longest staminate spikes 4.1--9.0 mm long; [s. Appalachian]

............ ....9 Primary culms to 13.5 cm tall; longest staminate spikes 3.6--6.2 mm long; [disjunct south to WV]

1 Primary culm solitary (i.e., lacking additional basal spikes originating from the same sheaths, excepting hybrids); however, some taxa may exhibit deceptively short individual culms (e.g., C. emmonsii, C. nigromarginata, C. reznicekii).

............ ......10 Body of the perigynium subglobose to obovoid, usually about as wide as long; achene angles broadly rounded.

............ ........11 Plants cespitose; leaves 0.9-4.7 mm wide; perigynium body pubescent, often with weak veins on the adaxial surface.

............ ..........12 Lowest proximal pistillate bract often shorter than the large, 3.5-15.5 mm long, terminal staminate spike; widest leaves usually > 3.0 mm wide; perigynia beaks narrow, surfaces papillate, often with weak veins on the adaxial surface

............ ..........12 Lowest proximal pistillate bract often exceeding the small, 3.2-5.6 mm long, terminal staminate spike; widest leaves typically < 3.0 mm wide; perigynia beaks deltoid, surfaces lacking easily discernible papillae and veins

............ ........11 Plants with long rhizomes, forming clonal patches; leaves 1.0-3.0 (-3.5) mm wide; perigynium body pubescent to nearly glabrous.

............ ............ 13 Larger perigynia 1.7-2.2 mm wide, papillae indiscernible under dense whitish trichomes; upper staminate scales acuminate to long-acuminate

............ ............ 13 Larger perigynia 1.2-1.7 mm wide; upper staminate scales acute to acuminate, papillae evident or not.

............ ............ ..14 Beak of perigynium (0.8-) 1.3-2.0 (-2.4) mm long; perigynium body pubescent or nearly glabrous, with or without papillae.

............ ............ ....15 Beak of the perigynium 1.1-2.4 mm long; widest leaf 1.3-2.3 (-3.7) mm wide; perigynium glabrous to sparsely pubescent over the body, papillae usually absent; culm nearly smooth; [of VA, WV, and KY southward]

............ ............ ....15 Beak of the perigynium 0.8-1.9 mm long; widest leaf 1.9-4.4 mm wide; perigynium usually moderately to densely pubescent over the body (rarely glabrate), papillae usually present; culm often scabrous; [of MD, NJ, and PA northward]

............ ............ ..14 Beak of perigynium (0.2-) 0.5-0.9 (-1.3) mm long; perigynium body pubescent and papillate.

............ ............ ......16 Beak of perigynium (0.5-) 0.6-1.3 mm long; hairs at base of the beak and below densely short-retrorse only on both surfaces; [high elevations of the s. Appalachians]

............ ............ ......16 Beak of perigynium (0.3-) 0.5-0.9 mm long; hairs at the base of the beak antrorse and those below either spreading, antrorse, or with retrorse hairs largely confined to one surface; [collectively more widespread].

............ ............ ........17 Widest leaves to 2.9 mm or greater; proximal bracts leaf-like; perigynia 2.3-3.7 mm long x 1.1-1.7 mm wide

............ ............ ........17 Widest leaves to 2.2 mm; proximal bracts setaceous; perigynia 2.2-3.2 mm long x 0.8-1.4 mm wide

............ ......10 Body of the perigynium ellipsoid, distinctly longer than wide; achene angles narrow to slightly rounded.

............ ............ ..........18 Plants with conspicuously long rhizomes, forming clonal patches; perigynia typically papillate; [collectively of the Coastal Plain and, less commonly, Piedmont].

............ ............ ............ 19 Achene body (1.1-) 1.2-1.3 (-1.4) mm long, trigonous; fertile culms 20-43 cm tall, equaling or exceeding the leaves; basal sheaths usually not fibrillose; pistillate scales (2.3-) 2.6-3.0 (-3.4) mm long

............ ............ ............ 19 Achene body (1.4-) 1.5-1.7 (-2.0) mm long, biconvex, trigonous, or both; fertile culms 7-17 cm tall, usually much shorter than the leaves; basal sheaths usually very fibrillose; pistillate scales (2.7-) 3.0-3.7 (-4.2) mm long

............ ............ ..........18 Plants cespitose (sometimes loosely so from slender rhizomes in C. novae-angliae and C. peckii); perigynia papillae not evident to rather conspicuous; [collectively widespread in our area].

............ ............ ............ ..20 Pistillate scales usually shorter than the body of the mature perigynia they subtend, perigynia without easily discernible papillae, lowermost 2 pistillate spikes remote, several separated by > 7 mm, staminate spike often elevated above pistillate spikes; leaves thin, delicate 0.7-1.5 mm wide

............ ............ ............ ..20 Pistillate scales mostly longer than the body of the mature perigynia they subtend, perigynia with discernible papillae, lowermost 2 pistillate spikes overlapping, usually separated by < 7 mm, staminate spike often closely associated with pistillate spikes; leaves various.

............ ............ ............ ....21 Plants slender-rhizomatous; pistillate scales longer than the mature perigynium body; perigynia surfaces villous, papillae obscured

............ ............ ............ ....21 Plants cespitose; pistillate scales shorter than the mature perigynium body; perigynia surfaces short pubescent to glabrate, papillae conspicuous.

............ ............ ............ ......22 Achene body (1.3-) 1.4-1.6 (-1.7) mm long; fertile culms mostly 2-20 cm tall; pistillate scales 2.6-4.3 mm long.

............ ............ ............ ........23 Culms usually variable in length, (4.5-) 6.6-38 (-51) cm tall; widest leaf (1.9-) 2.3-4.5 mm wide; at least some pistillate scales often with reddish to purplish/black color below the distal tip extending laterally from near the margin to the green or brown longitudinal mid-stripe on either side of midvein

............ ............ ............ ........23 Culms subequal in length, height 1.9–9.9 (–13.7) cm tall, widest leaf 1.2–2.2 (–2.5) mm wide; any reddish color on pistillate scales below the distal tip not extending laterally from near the margin to the green or brown longitudinal mid-stripe on either side of midvein

............ ............ ............ ......22 Achene body (0.9-) 1.2-1.3 (-1.5) mm long; fertile culms mostly 17-35 cm tall; pistillate scales 2.0-3.4 mm long.

............ ............ ............ ..........24 Scales of the median portion of the staminate spike with obtuse apices and with minute teeth rarely present on the midrib; staminate spike (7.8-) 8.0-12.5 (-13.5) mm long with peduncles mostly 1.0-6.0 mm; culms erect, subequal to the leaves; [mostly of loamy or clayey soils of the Piedmont and Mountains]

............ ............ ............ ..........24 Scales of the median portion of the staminate spike with acute-acuminate to aristate apices and with minute teeth usually present on the midrib; staminate spike (1.6-) 3.6-8.5 (-9.1) mm long with peduncles mostly 0.3-1.9 mm, exceeding uppermost pistillate spikes by 1.1-5.9 mm; culms lax to erect, often shorter than and curving under the leaves; [mostly of acid, sandy soils of the Coastal Plain]