1	"Flower stems all unisexual, either staminate or pistillate"	2
1	"Some or all flowering stems bisexual, with both staminate and pistillate flowers"	7
2	"Flower stems staminate"	3
2	"Flower stems pistillate"	5
3	"Flower stem base scaly, not fibrous; spikelets 1--4; anthers 2--2.8 mm"	"Carex scabriuscula"
3	"Flower stem base +- fibrous, scaly or not; spikelet 1; anthers 3.1--4.5 mm"	4
4	"Leaf sheath front occasionally hairy, not coarse-veined, fine-red-dotted; ligule occasionally longer than wide"	"Carex scirpoidea subsp. pseudoscirpoidea"
4	"Leaf sheath front glabrous, coarse-veined, generally not red-dotted; ligule wider than long"	"Carex serpenticola"
5	"Peri flat except over relatively small fruit, peri veins strong on lower 1/2 (obscure if dark purple)"	"Carex scabriuscula"
5	"Peri plump, filled by fruit, peri veins 0 or short, weak on lower 1/2"	6
6	"Spikelets generally 1 (2, overlapped), oblong-cylindric; mature stems stiffly erect"	"Carex scirpoidea subsp. pseudoscirpoidea"
6	"Spikelets 2--4, lowest generally well-separated or obvious, generally elliptic-ovate to +- spheric; mature stems weak, drooping"	"Carex serpenticola"
7	"Stigmas 4, warty, not plumose, at 15×; fruit base 4-angled; leaf sheath mouth V-shaped; leaves +- sickle-shaped --- KR, NCoR"	"Carex concinnoides"
7	"Stigmas 3, fine-plumose at 15&times;; fruit base 3-angled; leaf sheath mouth U-shaped; leaves straight (except <i>Carex brevicaulis</i> sickle-shaped)"	8
8	"Basal spikelets present"	9
8	"Basal spikelets 0"	14
9	"Peri with 12--20 strong veins at least to midbody; pistillate flower bracts generally prominently 3--5-veined"	10
9	"Peri with 2 strong veins, veins otherwise 0 or faint; pistillate flower bracts prominently 1(3)-veined"	12
10	"Leaves pale blue-green or glaucous; peri stalks +- = beaks; peri bodies barrel-shaped; leaves generally papillate abaxially at 40&times;"	"Carex brainerdii"
10	"Leaves green, not glaucous; peri stalks 1.5--2 &times; beaks; peri bodies obovoid; leaves not papillate or papillate only on veins abaxially at 40&times;"	11
11	"Some basal spikelets on generally arching, long, slender stalk > 10 cm; peri <= 2.3 mm wide; peri stalks <= 2.2 mm; coastal moist forest, openings"	"Carex globosa"
11	"All basal spikelets on stiffly erect stalks < 8 cm; peri <= 1.9 mm wide; peri stalks <= 1.6 mm; inland dry forest, savannah, chaparral"	"Carex xerophila"
12	"Inflorescence bracts on taller (non-basal) stems inconspicuous, scale-like, < inflorescence; old leaves occasionally persisting as shredded fibrous tufts; peri 1.5--2.1 mm wide; coastal dunes, headlands, NCo, CCo"	"Carex brevicaulis"
12	"Inflorescence bracts on taller (non-basal) stems prominent, leaf-like, generally >= inflorescence; old leaves not persisting as shredded fibrous tufts; peri 1--1.7 mm wide; NCo, CCo, and elsewhere"	13
13	"Peri 2.3--3.1 mm, beak 0.4--0.8 mm, teeth 0.1--0.2 mm; stems generally spreading or arching, +- smooth except near inflorescence; plant loosely cespitose; rhizomes slender"	"Carex deflexa var. boottii"
13	"Peri 3.1--4.5 mm, beak 0.7--1.7 mm, teeth 0.2--0.4 mm; stems generally ascending, scabrous; plant loosely to densely cespitose; rhizomes stout"	"Carex rossii"
14	"Staminate spikelets 2--3"	15
14	"Staminate spikelet 1 (except <i>Carex triquetra</i>, <i>Carex obispoensis</i> with 1--2 upper lateral spikelets occasionally staminate/pistillate, but not entirely staminate)"	19
15	"Stems 10--50 cm; dry uplands, Siskiyou Co."	"Carex halliana"
15	"Stems 60--180 cm; wet soil, Siskiyou Co. and elsewhere"	16
16	"Plants cespitose (<i>Carex spissa</i> cespitose to rhizomed); peri sparse-hairy, sharp-3-angled or 2-edged, generally fine-red-dotted; springs, seeps, streambanks, generally not in standing water, often on serpentine; CCo, SCoRO, SCo"	17
16	"Plants rhizomed; peri dense-hairy, plump, not sharp-3-angled or 2-edged, green or dark-purple-splotched; often emergent in shallow water, not on serpentine; widespread"	18
17	"Peri sharp-3-angled, lanceolate, gradually narrowed to long beak +- 2 mm; lateral spikelets with 15--45 peri; generally on serpentine; SCoRO (Monterey, San Luis Obispo cos.), PR"	"Carex obispoensis"
17	"Peri often +- flat, 2-edged, or strongly inflated, but not 3-angled, obovoid, abruptly narrowed to beak +- 0.5 mm; lateral spikelets with 150--300 peri; on serpentine or not; CCo, SCo"	"Carex spissa"
18	"Leaf blades inrolled to triangular-channeled, 0.7--2(2.2) mm wide, those of vegetative shoots especially prolonged into curled, thread-like tips; midvein of leaf, inflorescence bract a low, rounded, inconspicuous keel at least toward base"	"Carex lasiocarpa"
18	"Leaf blades flat or folded into an M-shape except at base and near tip, (2)2.2--4.5(6) mm wide, not prolonged into thread-like tips; midvein of leaf, inflorescence bract a prominent, sharp keel"	"Carex pellita"
19	"Spikelets 1, terminal"	20
19	"Spikelets > 1, terminal and lateral"	21
20	"Longest pistillate flower bracts (except awns) generally < 2.5 mm, generally << peri; peri body generally abruptly narrowed to beak 0--0.4 mm; fruit 1.6--2.4 mm"	"Carex filifolia var. erostrata"
20	"Longest pistillate flower bracts (except awns) generally > 3 mm, generally >= peri; peri body +- gradually narrowed to beak 0.1--0.8 mm; fruit 2.2--3 mm"	"Carex filifolia var. filifolia"
21	"Lateral spikelets generally < 1 cm; mouth of leaf sheath fine-toothed"	22
21	"Lateral spikelets generally > 1.5 cm; mouth of leaf sheath entire or fine-ciliate"	24
22	"Rhizomes short, plants loosely cespitose; peri 1--1.4 mm wide"	"Carex deflexa var. boottii"
22	"Rhizomes elongate, plants generally scattered; peri 1.5--2.2 mm wide"	23
23	"Pistillate flower bracts, lower staminate flower bracts green, red, or purple with white margin 0.4--0.8 mm wide; terminal spikelet staminate on taller inflorescences; stems bisexual; CaRH"	"Carex inops subsp. inops"
23	"Pistillate flower bracts, lower staminate flower bracts dark purple with white margin 0.1--0.2 mm wide; terminal spikelet on taller inflorescences staminate, pistillate, or pistillate/staminate; stems unisexual or bisexual; KR"	"Carex serpenticola"
24	"Plant rhizomed; leaf blade smooth; often in pumice --- KR, CaRH"	"Carex halliana"
24	"Plant cespitose; leaf blade smooth, scabrous, or minute-papillate; not in pumice"	25
25	"Peri hairs obvious, not sparse"	26
25	"Peri hairs 0 or occasionally inconspicuous, sparse"	27
26	"Peri lanceolate, +- gradually narrowed to beak +- 2 mm; generally on serpentine; SCoRO (Monterey, San Luis Obispo cos.), PR"	"Carex obispoensis"
26	"Peri elliptic, abruptly narrowed to beak < 1 mm; not on serpentine; CCo, SCo, s ChI, TR, PR"	"Carex triquetra"
27	"Spikelets <= 60 mm; peri, pistillate flower bract green to brown, occasionally red-marked; generally on serpentine"	"Carex mendocinensis"
27	"Spikelets <= 32 mm; peri, pistillate flower bract red-brown to dark purple, or green, marked with red-brown to dark purple; generally not on serpentine"	28
28	"Peri, at least distally on faces, with sparse, spreading-ascending, short, stiff, stout hairs or bristles; flower bract midvein distal margin scabrous to ciliate"	"Carex fissuricola"
28	"Peri faces generally glabrous or with sparse, spreading to appressed, generally long, soft, thin hairs; flower bract midvein, margin glabrous"	"Carex luzulina"