1	Pistillate scales scabrous-awned, margins often ciliate.		(2)
+	Pistillate scales awnless (rarely the proximal awned in C. rostrata and C. utriculata), margins entire.		(8)
2 (1)	Plants extensively colonial, not cespitose, rhizomes elongate; apex of staminate scales acute to acuminate, essentially smooth-margined except at tip; perigynia 7–11-veined.		387 Carex schweinitzii
+	Plants densely to loosely cespitose, rhizomes connecting individual culms in clump no more than 10 cm; apex of at least some staminate scales scabrous-awned, sometimes also ciliate-margined; perigynia 5–12- or 12–25-veined.		(3)
3 (2)	Perigynia 5–12-veined, veins separate nearly to beak apex, bodies broadly elliptic to ± round, (1.8–)2–4.2 mm wide; achenes rough-papillose.		(4)
+	Perigynia 12–25-veined, veins (except for 2 prominent laterals) confluent at or proximal to mid beak, bodies elliptic to lance-ovate, 1–2.2 mm wide; achenes smooth.		(5)
4 (3)	Spikes (12–)15–22 mm thick; widest leaves (4–)4.5–13 mm wide; if spikes less than 15 mm thick, then usually less than 2.5 times as long as wide; perigynia (6–)6.5–10.8 mm; beak 0.7–0.9 times length of body.		385 Carex lurida
+	Spikes 9–14(–15) mm thick; widest leaves 2.4–4(–5) mm wide; spikes usually 2.5–3.5 times as long as wide; perigynia 4.8–6.6(–7.6) mm; beak 0.7–1.3 times length of body.		386 Carex baileyi
5 (3)	Perigynia ± reflexed when mature, leathery, uninflated, compressed-triangular, strongly and closely veined with most veins separated by less than 2 times their width; longest beak teeth 0.7–2.1(–2.8) mm.		(6)
+	Perigynia spreading to ascending, herbaceous, ± inflated, terete to somewhat flattened, many veins separated by more than 3 times their width; longest beak teeth 0.3–0.9 mm.		(7)
6 (5)	Spikes 12–18 mm thick; beak teeth strongly out-curved, longest 1.3–2.1 (–2.8) mm.		391 Carex comosa
+	Spikes 9–12 mm thick; beak teeth straight or slightly out-curved, longest teeth 0.7–1.2(–1.4) mm.		390 Carex pseudocyperus
7 (5)	Perigynium beak 1.9–2.8 mm; pistillate scale bodies mostly truncate to retuse at apex, awn mostly longer than body.		388 Carex hystericina
+	Perigynium beak 0.9–1.8 mm; at least middle and distal pistillate scale bodies obtuse to acuminate, tapering to awn shorter than body.		389 Carex thurberi
8 (1)	Leaves filiform-involute, wiry, (0.5–)1–3(–3.2) mm wide; culms round or obtusely trigonous.		(9)
+	Leaves flat, U-, V-, or W-shaped in cross section, widest 1.5–12(–15) mm wide; culms round to trigonous.		(10)
9 (8)	Perigynia distinctly veined, veins extending into beak, 4–6.7 × 2.5–3.4 mm, leathery.		376 Carex oligosperma
+	Perigynia obscurely veined, veins not extending into beak, 2.5–3.9(–4.2) × 1.4–2.3 mm, membranaceous.		375 Carex rotundata
10 (8)	Perigynia obscurely veined, veins not running into beak, often dark-colored; beak less than 1 mm, emarginate at apex; stigmas 2 or 3.		(11)
+	Perigynia distinctly veined, veins running into beak, often green or straw colored; beak usually more than 1 mm, distinctly toothed at apex; stigmas 3.		(12)
11 (10)	Stigmas 2; perigynia ascending; culms arising from short, congested rhizomes.		373 Carex saxatilis
+	Stigmas 3; perigynia spreading or reflexed; culms arising from long, lax rhizomes.		374 Carex membranacea
12 (10)	Achenes asymmetric, deeply indented or invaginated on 1 face; widest perigynia (4–)4.5–7 mm wide; beak 2.4–4.8 mm.		379 Carex tuckermanii
+	Achenes symmetric, not indented or invaginated; widest perigynia (1.5–)2.5–3.5(–4.5) mm wide; beak 1–4.2(–4.8) mm.		(13)
13 (12)	Perigynium beak 2.4–4.2(–4.8) mm, finely scabrous, at least near the tip and on teeth; widest leaves 1.8–4.3(–5) mm wide.		378 Carex bullata
+	Perigynium beak 1–4.5 mm, smooth; widest leaves 1.5–15 mm wide.		(14)
14 (13)	Pistillate spikes globose or short-ovoid, ca. 3–20-flowered.		377 Carex elliottii
+	Pistillate spikes cylindric, ca. 20–150-flowered.		(15)
15 (14)	Bract of proximal pistillate spike (isolated spikes from long-sheathing bracts on proximal part of stem excepted) (2.5–)3–9 times longer than inflorescence; staminate spike often 1, slightly if at all elevated beyond summit of crowded pistillate spikes; perigynia reflexed.		384 Carex retrorsa
+	Bract of proximal pistillate spike shorter to no more than 2.5 times longer than inflorescence; staminate spikes 2–4(–5), well elevated beyond summit of separate pistillate spikes; perigynia spreading or ascending.		(16)
16 (15)	Leaves strongly papillose on adaxial surface, U-shaped in cross section, whitish green, widest leaves 1.5–4.5(–7.5) mm wide; culms terete to trigonous, smooth distally; plants rhizomatous; ligules as long as wide.		382 Carex rostrata
+	Leaves smooth or scabrous on adaxial surface, flat or folded, pale to dark green, widest leaves (2.5–)3–12(–15) mm wide; culms trigonous, scabrous distally; plants rhizomatous or not; ligules shorter to longer than wide.		(17)
17 (16)	Plants colonial; rhizomes elongate, creeping; widest leaves 4.5–12(–15) mm wide; ligules as long as wide; basal sheaths usually spongy-thickened, slightly red tinged or not.		383 Carex utriculata
+	Plants cespitose; rhizomes short; widest leaves 1.8–6.5 mm wide; ligules longer than wide; basal sheaths not spongy, thickened and often tinged with reddish purple.		(18)
18 (17)	Perigynia ovate to narrowly ovate, longest 4.8–7.5(–8.2) mm, 2–3.5 times as long as wide, papery, inflated, apex contracted; beak distinct.		380 Carex vesicaria
+	Perigynia lanceolate, longest 7.5–10.1 mm, 3.4–5 times as long as wide, leathery, not or slightly inflated, apex gradually tapering; beak indistinct.		381 Carex exsiccata