Jepson eFlora: Key page
Vascular Plants of California
Key to families | Table of families and genera

Key to Carex

View taxon page for Carex

(For a list of species in Carex, use the above link.)

Jepson Manual glossary definitions can be seen by moving your cursor over words underlined with dots.

Key to Groups

1. Plant hairy at least in part (check sheathsblades, peri)

2. Leaves hairy; peri hairy or glabrous ..... Group 1

2' Leaves glabrous; peri hairy ..... Group 2

1' Plant completely glabrous throughout

3. Inflorescenceterminal  ..... Group 3

3' Inflorescence generally >= 2 

4. Stigmas 3; fruit 3-angled

5. Inflorescence   >= 6 mm ..... Group 4

5' Inflorescence bract sheath < 5 mm

6. Peri inflated at least near beak ..... Group 5

6' Peri not inflated ..... Group 6

4' Stigmas 2; fruit lenticular

7. Pistillate and staminate flowers on different stems (unisexual stems) ..... Group 7

7' Pistillate and staminate flowers on same stem (bisexual stems)

8. Terminal spikelet(s) generally staminate; lateral spikelets pistillate (rarely tips staminate) ..... Group 8

8' Terminal and lateral spikelets all a mix of staminate and pistillate flowers

9. Spikelets each with staminate flowers above pistillate flowers (often easiest to see in terminal spikelet; look for remnants of stamens) ..... Group 9

9' Spikelets each with pistillate flowers above staminate flowers

10. Peri not winged (occasionally thin-edged above); stem generally solid;  or rhizomed ..... Group 10

10' Peri winged; stem hollow; cespitose ..... Group 11

Group 1: Sheaths and/or blades hairy

1. Plants dioecious

2. Spikelets 1–4; plant loosely fruit << peri body ..... C. scabriuscula

2' Spikelet generally 1; plant rhizomed; fruit ± = peri body ..... C. scirpoidea subsp. pseudoscirpoidea

1' Plants monoecious

3. Leaf blades glabroussheaths hairy at least at mouth

4. Peri glabrous; leaves 1.5–23 mm wide

5. Longer teeth of peri beak 1.5–3.3 mm, curved ..... C. atherodes (2)

5' Longer teeth of peri beak < 0.5 mm, straight

6. Plant rhizomed; leaves 8–23 mm wide; peri abruptly narrowed to beak ..... C. amplifolia

6' Plant cespitose; leaves 1.5–5.5 mm wide; peri gradually narrowed to beak7. Distal lateral  arching or drooping, 0.7–3.5(6) mm between peri at mid-spikelet; proximal staminate flower   0.5–5 mm; pistillate flower bracts, including awns, (2.2)3–4.8(6.8) mm, awns (0)0.5–2.2(3.1) mm ..... C. cyrtostachya

7' Distal lateral spikelets  or , 0.3–0.6(1.2) mm between peri at mid-spikelet; proximal staminate flower bract awns 0 (0.3–0.5 mm); pistillate flower bracts, including awns, 1.7–3.2(3.7) mm, awns 0–0.3(2) mm ..... C. mendocinensis (3)

4' Peri hairy; leaves 1.5–8 mm wide

8. Plant rhizomed; often in standing water ..... see couplet 5

8' Plant cespitose; upland or damp ground, rarely in standing water

9. Pistillate flower bract face hairy; lowest inflorescence bract  < 5 mm; spikelets, upper 1/2 of peri dark purple; talus, 2600–3900 m ..... C. congdonii (2)

9' Pistillate flower bract face glabrous; lowest inflorescence bract sheath 20–30 mm; spikelets, peri green to gold or pale brown; moist ground, often on serpentine, 150–1600 m ..... C. mendocinensis (3)

3' Leaf blades hairy, sheaths hairy or glabrous

10. Plant long-rhizomed; sheath fronts occasionally 

11. Peri sparse-hairy on main veins or glabrous; longer teeth of peri beak 1.5–3.3 mm ..... C. atherodes (2)

11' Peri dense-hairy; longer teeth of peri beak 0.2–1.4 mm

12. Peri gradually narrowed to long beak; fruit << peri body;  sheaths white, not red-dotted, not fibrous; mature spikelets 8–10 mm wide ..... C. sheldonii

12' Peri ± abruptly narrowed to beak; fruit ± = body; leaf sheaths often red-dotted, fibrous; mature spikelets 4–7 mm wide

13. 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 ..... C. lasiocarpa

13' 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 ..... C. pellita

10' Plant cespitose to loosely so, forming clumps; sheath fronts not fibrous

14. Lowest inflorescence bract sheath < 5 mm; terminal  staminate; not on serpentine

15. Peri glabrous, face strongly 5-veined; pistillate flower bracts glabrous; stem brown (red-brown) at base ..... C. whitneyi

15' Peri hairy, face faintly 0–10 veined; pistillate flower bracts hairy near tips; stem red to purple at base

16. Pistillate flower bracts dark purple with 1–5 pale brown, strong veins; spikelets dark; peri > pistillate flower bracts, purple on upper 1/2 of body, gradually narrowed above; talus, 2600–3900 m ..... C. congdonii (2)

16' Pistillate flower bracts with 1 weak vein in wide central green zone; spikelets light; peri < or > pistillate flower bracts, green to dark brown (dark purple) on upper 1/2 of body, generally abruptly narrowed above; moist or wet sites, 1200–2600 m ..... C. sartwelliana

14' Lowest inflorescence bract sheath > 5 mm; terminal spikelet staminate or staminate and pistillate; generally on serpentine

17. Peri generally glabrous (sparse-hairy toward tip); leaf  glabrous or sparsely hairy at base;  leaves 1.5–5.5 mm wide ..... C. mendocinensis (3)

17' Peri hairy; leaf blade hairy; basal leaves occasionally > 7 mm wide

18. Pistillate flower bracts obovate to wide-elliptic, red-brown or ± purple, midrib green; peri purple-splotched; on serpentine, < 600 m, NCo, KR, NCoRO, n CCo (Marin, Santa Cruz cos.), SnFrB, SCoRO ..... C. gynodynama

18' Pistillate flower bracts  to elliptic-obovate, green or pale red-brown, midrib green; peri green or gold-green to pale brown, occasionally red-dotted but not purple-splotched; often on serpentine, 60–1200 m, NCoR (Mendocino, Lake cos.), CaR, n&c SN ..... C. hirtissima

Group 2: Peri hairy

1. Flower stems all unisexual, either staminate or pistillate

2. Flower stems staminate

3. Flower stem base scaly, not  1–4; anthers 2–2.8 mm ..... C. scabriuscula (2)

3' Flower stem base ± fibrous, scaly or not;  1; anthers 3.1–4.5 mm

4. Leaf  front occasionally hairy, not coarse-veined, fine-red-dotted;  occasionally longer than wide ..... C. scirpoidea subsp. pseudoscirpoidea (2)

4' Leaf sheath front glabrous, coarse-veined, generally not red-dotted; ligule wider than long ..... C. serpenticola (3)

2' Flower stems pistillate

5. Peri flat except over relatively small fruit, peri veins strong on lower 1/2 (obscure if dark purple) ..... C. scabriuscula (2)

5' Peri plump, filled by fruit, peri veins 0 or short, weak on lower 1/2

6. Spikelets generally 1 (2, overlapped), oblong-cylindric; mature stems stiffly  ..... C. scirpoidea subsp. pseudoscirpoidea (2)

6' Spikelets 2–4, lowest generally well-separated or obvious, generally elliptic-ovate to ± spheric; mature stems weak, drooping ..... C. serpenticola (3)

1' Some or all flowering stems , with both staminate and pistillate flowers

7. Stigmas 4, warty, not , at 15×; fruit base 4-angled;  sheath mouth V-shaped; leaves ± sickle-shaped – KR, NCoR ..... C. concinnoides

7' Stigmas 3, fine-plumose at 15×; fruit base 3-angled; leaf sheath mouth U-shaped; leaves straight (except Carex brevicaulis sickle-shaped)

8. Basal spikelets present

9. Peri with 12–20 strong veins at least to midbody; pistillate flower bracts generally prominently 3–5-veined

10. Leaves pale blue-green or glaucous; peri stalks ± = beaks; peri bodies barrel-shaped; leaves generally  abaxially at 40× ..... C. brainerdii

10' Leaves green, not glaucous; peri stalks 1.5–2 × beaks; peri bodies obovoid; leaves not papillate or papillate only on veins abaxially at 40×

11. Some  spikelets on generally arching, long, slender stalk > 10 cm; peri <= 2.3 mm wide; peri stalks <= 2.2 mm; coastal moist forest, openings ..... C. 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 ..... C. xerophila

9' Peri with 2 strong veins, veins otherwise 0 or faint; pistillate flower bracts prominently 1(3)-veined

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 ..... C. 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. Peri 2.3–3.1 mm, beak 0.4–0.8 mm, teeth 0.1–0.2 mm; stems generally  or arching, ± smooth except near inflorescence; plant loosely rhizomes slender ..... C. deflexa var. boottii (2)

13' Peri 3.1–4.5 mm, beak 0.7–1.7 mm, teeth 0.2–0.4 mm; stems generally scabrous; plant loosely to densely cespitose; rhizomes stout ..... C. rossii

8' Basal spikelets 0

14. Staminate spikelets 2–3

15. Stems 10–50 cm; dry uplands, Siskiyou Co. ..... C. halliana (2)

15' Stems 60–180 cm; wet soil, Siskiyou Co. and elsewhere

16. Plants cespitose (Carex spissa 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. Peri sharp-3-angled, , gradually narrowed to long beak ± 2 mm; lateral spikelets with 15–45 peri; generally on serpentine; SCoRO (Monterey, San Luis Obispo cos.), PR ..... C. obispoensis (2)

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 ..... C. spissa

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. 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  a low, rounded, inconspicuous keel at least toward base ..... C. 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 ..... C. pellita

14' Staminate spikelet 1 (except Carex triquetra, Carex obispoensis with 1–2 upper lateral spikelets occasionally staminate/pistillate, but not entirely staminate)

19. Spikelets 1, terminal ..... C. filifolia

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 ..... 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 ..... var. filifolia

19' Spikelets > 1, terminal and lateral

21. Lateral spikelets generally < 1 cm; mouth of leaf sheath fine-toothed

22. Rhizomes short, plants loosely cespitose; peri 1–1.4 mm wide ..... C. deflexa var. boottii (2)

22' Rhizomes elongate, plants generally scattered; peri 1.5–2.2 mm wide

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; KR, CaRH ..... C. 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 ..... C. serpenticola (3)

21' Lateral spikelets generally > 1.5 cm; mouth of leaf sheath  or fine-ciliate

24. Plant rhizomed; leaf  smooth; often in pumice – KR, CaRH ..... C. halliana (2)

24' Plant cespitose; leaf blade smooth, scabrous, or minute-papillate; not in pumice

25. Peri hairs obvious, not sparse

26. Peri lanceolate, ± gradually narrowed to beak ± 2 mm; generally on serpentine; SCoRO (Monterey, San Luis Obispo cos.), PR ..... C. obispoensis (2)

26' Peri , abruptly narrowed to beak < 1 mm; not on serpentine; CCo, SCo, s ChI, TR, PR ..... C. triquetra

25' Peri hairs 0 or occasionally inconspicuous, sparse

27. Spikelets <= 60 mm; peri, pistillate flower bract green to brown, occasionally red-marked; generally on serpentine ..... C. 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. Peri, at least distally on faces, with sparse, spreading-ascending, short, stiff, stout hairs or bristles; flower bract midvein distal margin scabrous to  ..... C. fissuricola

28' Peri faces generally glabrous or with sparse, spreading to , generally long, soft, thin hairs; flower bract midvein, margin glabrous ..... C. luzulina

Group 3: Spikelet 1

1. Lowest pistillate flower bracts green, leaf-like, 1–15 cm, base clasping peri; peri with bristle-like axis inside

2. Upper stem round or blunt-3–angled, generally smooth toward tip; peri with 2 strong marginal veins, several faint veins; longest leaves much exceeded by inflorescenceblades inrolled or flat, 0.8–1.5 mm wide; plant  ..... C. multicaulis

2' Upper stem sharp-3–angled, scabrous toward tip; peri with 2 strong marginal veins, generally 0 faint veins; longest leaves ± equaling inflorescence, blades flat, 1.5–3 mm wide; plant loosely cespitose ..... C. tompkinsii

1' Lowest pistillate flower bracts not green, not leaf-like, <= 1.5 cm, base clasping peri or not; peri with bristle-like axis inside or not

3. Peri body wide-elliptic to ± round

4. Peri 2–4.8 mm wide; generally some lower pistillate flower bracts 3- or 5-veined; dry soil ..... C. breweri

4' Peri 1.5–1.8 mm wide; lower pistillate flower bracts 1-veined; wet or seasonally wet soil

5. Stigmas 2; leaves green, <= 1 mm wide; peatland, moist alpine meadows ..... C. capitata

5' Stigmas 3; leaves ± glaucous, 2–5 mm wide; meadows ..... C. idahoa (2)

3' Peri body narrowly  to oblanceolate

6. Peri green, tip blunt, beak 0

7. Peri obovoid, marginal veins 2, fine veins 0 ..... C. geyeri (2)

7' Peri elliptic to narrow-oblong-elliptic, with many fine veins ..... C. leptalea

6' Peri green or straw to dark purple, tip pointed or distinctly beaked

8. Peri 1–3 per stem, 4.9–7 mm; leaves evergreen ..... C. geyeri (2)

8' Peri 8–50 per stem, 2–5 mm; leaves deciduous

9. Mature peri gradually narrowed to ± long stalk and beak; peri narrow-elliptic, often ±  to  or ; pistillate flower bracts shed before peri ..... C. nigricans

9' Mature peri abruptly narrowed to short stalk or beak or both; peri elliptic to obovate, ascending or ; pistillate flower bracts persisting with peri

10. Leaves ± glaucous, flat, 2–5 mm wide; peri without bristle-like axis inside ..... C. idahoa (2)

10' Leaves green, not glaucous, inrolled or channeled, 0.4–1 mm wide; peri with bristle-like axis inside ..... C. subnigricans

Group 4: Stigmas 3; inflorescence bract sheath >= 6 mm

1. Plant rhizomed

2. Peri inflated; style persisting on fruitstem base spongy-thickened;  sheaths, lower leaf blades with well-developed brickwork pattern of crosswalls ..... C. utriculata

2' Peri not inflated; style breaking off near fruit; stem base not spongy-thickened; leaf sheaths, lower leaf blades without well-developed brickwork pattern of crosswalls

3. Stigmas 2–3 (generally an even mix on a stem), ripe fruit lenticular or 3-angled; serpentine wetlands, KR ..... C. hassei

3' Stigmas 3, ripe achenes 3-angled; various (including serpentine) wetlands or meadows, KR and elsewhere

4. Peri beak distinct or indistinct, 0.5–1.5 mm; leaves green, not glaucous

5. Stem base red or purple; peri abruptly narrowed to distinct beak; lower leaves on flowering stems reduced to bladeless sheaths ..... C. californica

5' Stem base brown; peri gradually narrowed to indistinct beak; lower leaves on flowering stems well developed ..... C. luzulina (4)

4' Peri beak indistinct, < 0.5 mm; leaves glaucous

6. Peri beak bent to 1 side; peri obovate, veins generally strong; leaves flat or folded; serpentine fens; KR, NCoRI ..... C. klamathensis

6' Peri beak straight; peri , veins weak or 0; leaves channeled; coastal peatland, not on serpentine; NCo (Mendocino Co.) ..... C. livida

1' Plant  to loosely so (Carex spissa cespitose to rhizomed)

7. Peri beak teeth , generally curved, 1.3–2.8 mm ..... C. comosa

7' Peri beak teeth 0 or , straight, < 1 mm

8. Terminal  generally pistillate/staminate

9. Pistillate flower bracts white; peri 1.3–2.3 mm ..... C. tiogana (2)

9' Pistillate flower bracts red-brown or purple; peri 3–5.5 mm

10. Peri plump, 0.9–2 mm wide

11. Peri not  to  ..... C. luzulina (4)

11' Peri papillate, wide-elliptic to ovate ..... C. serratodens

10' Peri flat, 1.7–3.5 mm wide

12. Lateral  pistillate, larger with < 50 peri ..... C. heteroneura

12' Lateral spikelets generally pistillate/staminate, larger with > 60 peri ..... C. mertensii

8' Terminal spikelet generally staminate or staminate/pistillate (pistillate/staminate)

13. Wider leaves 9–20 mm wide; stems often weak, leaning

14. Peri gradually narrowed to indistinct beak; spikelets erect or spreading

15. Peri 4.3–6.5 mm, 20–32-veined, not red-dotted; inflorescence  sheaths inflated; fruit stems often ; coastal forest, not on serpentine, < 900 m ..... C. hendersonii

15' Peri 2.5–4.3 mm, finely 8–10-veined, occasionally red-dotted; inflorescence bract sheaths not inflated; fruit stems erect or ; openings, mixed-evergreen forest, disturbed wet places, often on serpentine, 60–1200 m ..... C. hirtissima

14' Peri abruptly narrowed to distinct beak; spikelets erect to spreading or drooping

16. Spikelets 1–3 cm, dark purple; peri < 30, margins flat; leaves green; 1900–3100 m ..... C. luzulifolia (2)

16' Spikelets 3–20 cm, green; peri generally > 75, margins not flat; leaves blue-green, at least when young; < 1200 m

17. Peri body elliptic, 1.1–1.5 mm wide; stem base red to purple; pistillate spikelets 5–8 mm wide ..... C. pendula

17' Peri body obovate, 1.5–2.5 mm wide; stem base brown; pistillate spikelets 7–12 mm wide ..... C. spissa

13' Wider leaves generally 1–8 mm wide; stems erect or leaning

18. Spikelets ± , erect; inflorescence bracts ± stiff, ascending or spreading; peri green to ± yellow or brown

19. Peri body lanceolate, gradually narrowed to indistinct beak ..... C. lemmonii (2)

19' Peri body elliptic to ovate or obovate, abruptly narrowed to distinct beak ..... C. viridula subsp. viridula

18' Spikelets stalked, erect or arching to drooping; inflorescence bracts ± weak, spreading; peri white, green, brown, red-brown, or purple

20. Peri beak distinct, <= 0.5 mm, or indistinct

21. Peri 1.3–2.3 mm, 0.4–0.9 mm wide; pistillate flower bract white ..... C. tiogana (2)

21' Peri 3–5.5 mm, 0.9–2 mm wide; pistillate flower bract red-brown or dark purple

22. Peri body ovate to lanceolate, gradually narrowed to indistinct beak ..... C. luzulina (4)

22' Peri body obovate to wide-elliptic, abruptly narrowed to distinct beak ..... C. raynoldsii

20' Peri beak distinct, generally > 0.5 mm

23. Pistillate spikelets (15)20–60 mm, ; peri beak  on inner side of teeth

24. Distal lateral spikelets arching or drooping, 0.7–3.5(6) mm between peri at mid-spikelet; proximal staminate flower bract  0.5–5 mm; pistillate flower bracts, including awns, (2.2)3–4.8(6.8) mm, awns (0)0.5–2.2(3.1) mm ..... C. cyrtostachya

24' Distal lateral spikelets erect or ascending, 0.3–0.6(1.2) mm between peri at mid-spikelet; proximal staminate flower bract awns 0 (0.3–0.5 mm); pistillate flower bracts, including awns, 1.7–3.2(3.7) mm, awns 0–0.3(2) mm ..... C. mendocinensis

23' Pistillate spikelets generally <= 20 mm, ; peri beak generally not ciliate on inner side of teeth, but beak margins and outer side of teeth generally with spreading, stiff bristles

25. Peri faces, at least near beak, with sparse, spreading-ascending, short, stiff, bristles; pistillate flower bract margins ciliate distally ..... C. fissuricola

25' Peri faces generally glabrous (or with sparse, weak hairs); pistillate flower bract margins glabrous

26. Peri flat margin > 1/2 fruit width; peri 1.7–2.5 mm wide; inflorescence bract  expanded toward shallow-U-shaped mouth (1.8)2–3 mm wide ..... C. luzulifolia (2)

26' Peri flat margin 0 or < 1/2 fruit width; peri 0.9–2 mm wide; inflorescence bract sheath not (or ±) expanded toward shallow Y- or V-shaped mouth 0.6–2 mm wide

27. Peri beak tip to fruit tip < 1.5 mm; lowest spikelet stalk generally  < 10 mm; pistillate flower bracts white, green, gold, or red-brown to dark purple, margin white ..... C. lemmonii (2)

27' Peri beak tip to fruit tip >= 1.5 mm; lowest spikelet stalk exserted > 10 (> 5) mm; pistillate flower bracts generally red-brown to dark purple ..... C. luzulina (4)

Group 5: Stigmas 3; inflorescence bract sheath < 6 mm; peri inflated at least near beak

1. Lower lateral  nodding on drooping stalks

2. Peri strongly 7–11-veined, beak teeth without eroded tips, 0.3–2.8 mm

3. Peri beak teeth  or strongly curved, 1.3–2.8 mm, not prickle-like; stem base brown ..... C. comosa

3' Peri beak teeth , straight, 0.3–0.9 mm, prickle-like; stem base red-purple ..... C. hystericina

2' Peri weakly 0–7-veined, beak teeth with eroded tips or < 0.5 mm

4. Peri obovate;  margins very sharply scabrous ..... C. spissa (2)

4' Peri  to ; leaf margins smooth to ± 

5. Plant rhizomed; peri beak 0.7–1.2 mm ..... C. amplifolia

5' Plant ; peri beak 0.5 mm ..... C. pendula

1' Lower lateral spikelets generally erect, stalks sometimes 0

6. Lateral spikelets 4–20 mm; peri 1.8–4.5 mm

7. Pistillate flower bracts dark purple or black; peri 1.6–2.1 mm wide ..... C. raynoldsii

7' Pistillate flower bracts green to rusty; peri 0.8–1.6 mm wide ..... C. viridula subsp. viridula

6' Lateral spikelets 20–100 mm; peri 3.6–12.7 mm

8. Peri widest above middle, weakly veined; leaf margins very sharply scabrous; young leaves blue-green ..... C. spissa (2)

8' Peri widest below middle, strongly veined; leaf margins  or weakly serrate; young leaves green

9. Plant long-rhizomed; stem base spongy-thickened, brown or red-tinged, crosswalls between veins many, well developed, yielding brick-like pattern, sheaths generally not  length generally < width on lower leaves; widest leaves to 15 mm wide ..... C. utriculata

9' Plant ± cespitose; stem base not spongy-thickened, generally red- or purple-tinged, crosswalls between veins generally few, weakly developed, not yielding brick-like pattern; sheaths often fibrous; ligule length > width on lower leaves; widest leaves to 6.5 mm wide

10. Larger peri 7.5–12.7 mm, length 3.4–7.4 × width, tip gradually narrowed to an indistinct beak; < 1800 m ..... C. exsiccata

10' Larger peri 3.6–8.2 mm, length generally 2–3.5 × width, tip ± abruptly narrowed to ± distinct beak; < 3300 m ..... C. vesicaria

Group 6: Stigmas 3; inflorescence bract sheath < 6 mm; peri not inflated

1. Peri beak teeth curved, 1.3–2.8 mm ..... C. comosa

1' Peri beak teeth 0 or inconspicuous, straight, 0–1 mm

2. Leaves 8–23 mm wide; lateral  often with > 100 peri

3. Stem brown at base; upper 2–4 spikelets staminatesheaths, peri red-dotted ..... C. spissa

3' Stem ± red or ± purple at base; uppermost  staminate; sheaths, peri not red-dotted

4. Plant rhizomed; peri beak 0.7–1.1 mm ..... C. amplifolia

4' Plant ; peri beak 0.5 mm ..... C. pendula

2' Leaves < 8.5 mm wide; lateral spikelets with < 70 peri

5. Plant long-rhizomed; peri beak 0–0.5 mm; leaves glaucous; peri 

6. Peri abruptly narrowed to distinct beak

7. Peri beak straight, beak, upper body often minute-serrate or bristly; moist mountain meadows over dolomite, 2800–3400 m, W&I (White Mtns) ..... C. idahoa (3)

7' Peri beak bent to side, beak, upper body not minute-serrate, not bristly; serpentine fens, 450–900 m, KR, NCoRI ..... C. klamathensis

6' Peri  to indistinct beak

8. Spikelets nodding; roots with dense felt-like hairs ..... C. limosa

8' Spikelets  or ; roots without dense felt-like hairs

9. Pistillate flower bracts prominently awned; sheaths terminal spikelet pistillate/staminate ..... C. buxbaumii

9' Pistillate flower bracts awnless; sheaths not fibrous; terminal spikelet staminate ..... C. livida

5' Plant cespitose to loosely so; peri beak < to > 0.5 mm; leaves green or glaucous; peri papillate or not

10. Spikelets green to gold, pistillate flower bracts without dark purple or black

11. Peri 1.3–2 mm, beak 0.2–0.4 mm; pistillate flower bracts blunt or mucronate; 3100–3350 m, c SNH (Mono Co.) ..... C. tiogana

11' Peri 4.5–7.3 mm, beak 0 or 1.9–2.8 mm; pistillate flower bracts long-awned; < 1800 m, KR, SN

12. Terminal spikelet staminate; lateral spikelets 2–4, generally nodding, dense; peri rounded, > 25, ribs 3, veins 13–21, beak 1.9–2.8 mm, teeth prominent, 0.3–0.9 mm ..... C. hystericina

12' Terminal spikelet staminate flowers above pistillate; lateral spikelet 1, erect, not dense; peri 3-angled, 1–5, ribs 3, veins 0, beak 0, teeth 0 ..... C. tompkinsii

10' Spikelets darker than green to gold, pistillate flower bracts at least partly dark brown to dark purple or black

13. Terminal spikelet staminate (some species variable, keying here or at 13')

14. Peri ascending, <= 1/2 filled by fruit; lower spikelets often nodding on drooping stalks ..... C. spectabilis

14' Peri , > 1/2 filled by fruit; lower spikelets generally erect

15. Peri body  to widely , beak 0.3–1 mm, teeth generally bristly, 0.2–0.5 mm; < 1800 m, often on serpentine ..... C. serratodens (2)

15' Peri body elliptic to obovate, beak 0.1–0.5 mm, teeth 0 or smooth to bristly, < 0.2 mm; 1800–3200 m, not on serpentine

16. Lateral spikelets < terminal; peri 2–3 mm ..... C. idahoa (3)

16' Lateral spikelets >= terminal; peri 3.5–4.5 mm ..... C. raynoldsii

13' Terminal spikelet pistillate or pistillate/staminate (or staminate/pistillate/staminate in some Carex helleri)

17. Peri flat, < 1/2 filled by fruit, generally not papillate (± papillate near beak)

18. Lateral spikelets spreading or drooping, often > 2 cm, generally pistillate/staminate,  flowers with remnant filaments ..... C. mertensii

18' Lateral spikelets generally erect or ascending, generally < 2 cm, generally pistillate

19. Lower pistillate flower bracts  generally 0.5–2 mm; peri elliptic to obovate; stem 5–40 cm ..... C. helleri

19' Lower pistillate flower bracts  to acuminate, awns < 0.5 mm or generally 0; peri ovate to ± round or obovate; stem 25–100 cm ..... C. heteroneura

17' Peri plump, > 1/2 filled by fruit, papillate or not

20. Peri ovate to widely elliptic, generally 3–5 mm ..... C. serratodens (2)

20' Peri elliptic to obovate, generally 2–3 mm

21. Peri green to olive, obvious, strongly contrasting with, not hidden by shorter, darker pistillate flower bracts ..... C. stevenii

21' Peri yellow to dark brown to dark purple, hidden by or not contrasting with pistillate flower bracts

22. Peri upper body, beak not minute-serrate or bristly; pistillate flower bracts  or  to widely elliptic, tips not bristly ..... C. orestera

22' Peri upper body, beak minute-serrate or bristly; pistillate flower bracts obovate to widely elliptic, tips or awns bristly or not ..... C. idahoa (3)

Group 7: Spikelets 2+; stigmas 2; stems generally unisexual

1. Stems staminate or mostly so

2. Plant  to loosely so (Carex alma cespitose to rhizomed);  >= 1 per lower  or branch;   front red-dotted or not

3. Leaf sheath front not red-dotted; anther tips  0 ..... C. infirminervia (2)

3' Leaf sheath front red-dotted; anther tips with bristle-like awn <= 0.3 mm

4. Leaf sheath front not cross-wrinkled, colorless at mouth, rim not thick or dark, generally with contraligule ..... C. alma (2)

4' Leaf sheath front occasionally cross-wrinkled, copper or ± purple at mouth, rim often thick or dark, without contraligule ..... C. cusickii (2)

2' Plant rhizomed; spikelets generally 1 per node or branch; leaf sheath front generally not red-dotted

5. Stem angles smooth near tip; rhizomes 0.6–1.9 mm thick

6. Anther  0.2–1 mm, bristly at 30×; leaf blades 1–3.5 mm wide; inflorescence 12–45 mm ..... C. douglasii (2)

6' Anther awns < 0.1 mm, smooth to warty at 30×; leaf blades < 1.5 mm wide; inflorescence <= 20 mm ..... C. duriuscula (2)

5' Stem angles ± scabrous near tip; rhizomes 1.5–5 mm thick

7. Longest anther awns 0.2–0.4 mm, filaments generally stem generally < 40 cm; coastal, islands ..... C. pansa (2)

7' Longest anther awns 0.1–0.2 mm, filaments ; stem 20–75 cm; coastal or inland

8. Anther awns generally hairy at 20×; leaf sheath mouth occasionally with dark or ± thick rim; leaf blades 1.5–3 mm wide ..... C. praegracilis (2)

8' Anther awns glabrous (warty) at 20×; leaf sheath mouth with or without dark stripe, generally without thick rim; leaf blades 2–5 mm wide ..... C. simulata (2)

1' Stems pistillate or mostly so

9. Plant cespitose (Carex alma cespitose to rhizomed)

10. Leaf sheath front copper or ± purple at mouth, often with thick or dark rim, mouth generally concave or  ..... C. cusickii (2)

10' Leaf sheath front colorless at mouth, without thick or dark rim, mouth concave to convex

11. Leaf sheath front red-dotted; peri  to triangular-ovate; inflorescence a dense  of spikelets, spikelets generally several per lower node, or lower node long-branched with 3+ spikelets ..... C. alma (2)

11' Leaf sheath front not red-dotted; peri narrow-lanceolate; inflorescence a  of spikelets, spikelets 1 per node ..... C. infirminervia (2)

9' Plant rhizomed

12. Upper stem smooth on angles; rhizomes 0.6–1.8 mm thick; shoots often 2–several in small clusters, 0 at many 

13. Pistillate flower bracts 4.3–7.5 mm, pale brown to ± white; peri beak 0.9–1.9 mm; spikelets generally unisexualanthers 2.5–3.9 mm, tip 0.2–1 mm, bristly at 30× ..... C. douglasii (2)

13' Pistillate flower bracts 2.4–4.1 mm, red-brown; peri beak 0.3–0.9 mm; spikelets occasionally with staminate flowers above pistillate (as in Group 9); anthers 1.4–3 mm, awn < 0.1 mm, smooth to warty at 30× ..... C. duriuscula (2)

12' Upper stem ± scabrous on angles; rhizomes 1.5–5 mm thick; shoots generally 1 every few nodes

14. Peri beak 0.25–0.5 mm; contraligule 0.3–1.6 mm; anthers occasionally present, tip smooth to warty at 30× ..... C. simulata (2)

14' Peri beak 0.5–1.5 mm; contraligule 0; anthers occasionally present, tip bristly-hairy at 30×

15. Pistillate flower bracts, base of  bracts dark brown or purple-brown, generally shiny, darker than peri; pistillate inflorescence not elongate, ovate to ; coastal, islands ..... C. pansa (2)

15' Pistillate flower bracts, base of spikelet bracts pale brown to pale red-brown, ± dull, lighter than peri; pistillate inflorescence elongate, generally oblong-elliptic; generally inland ..... C. praegracilis (2)

Group 8: Stigmas 2, terminal spikelets generally staminate, lateral generally pistillate, rarely staminate-tipped

1. Peri fleshy, plump, often dense-papillate, tip blunt or with beak <= 0.3 mm;  of inflorescence  generally > 4 mm; plants long-rhizomed

2. Mature peri, just before dropping, bright orange (green to white when immature, as in many herbarium specimens), ± spheric, ± pistillate flower bracts spreading, often falling before peri; ripe peri smooth (often  when immature)..... C. aurea

2' Mature peri, just before dropping, green to white, occasionally purple- or red-brown-marked,  to elliptic-obovate, ; pistillate flower bracts ascending, generally ± persistent with peri; ripe peri dense-papillate at 10×

3. Upper 1/2 of peri generally green or white, ± abruptly rounded, blunt, or only slightly narrowed, red-brown generally only on small, occasionally bent beak, if present; lower staminate flower bracts blunt or short-awned, generally < 4 mm, not like inflorescence bract;  1 per lower  ..... C. hassei

3' Upper 1/2 of peri red-brown- or purple-splotched, gradually narrowed to tip or short straight beak; lower staminate flower bracts generally long-awned, >= 4.5 mm, like inflorescence bract; spikelets occasionally > 1 per lower node ..... C. saliniformis

1' Peri not fleshy, ± flat, papillate or not, tip distinctly beaked < or > 0.3 mm; sheath of inflorescence bract generally < 2 mm; plants long-rhizomed or 

4. Plant cespitose; peri veined

5. Leaf sheath fronts ; lower sheaths scabrous, red-brown to shiny dark brown

6. Stem 30–70 cm, < 1 cm wide at base; staminate spikelets 1–2, terminal < 5 cm; peri purple-splotched on upper 2/3; below high water mark on rocky streams ..... C. nudata

6' Stem 75–150 cm, ± 1 cm wide at base; staminate spikelets 2–7, terminal generally > 5 cm; peri red-spotted, generally more densely so toward base; creekbanks, wet meadowsswamps ..... C. schottii

5' Leaf sheath fronts not fibrous; lower sheaths glabrous, dull light brown ..... C. lenticularis

7. Lower spikelets 4–6 mm wide; peri stalks 0.4–0.7 mm; lower spikelets crowded, overlapping; peri = pistillate flower bracts; NCo, < 20 m ..... var. limnophila

7' Lower spikelets generally 3–4 mm wide; peri stalks 0.1–0.5 mm; lower spikelets generally more separated; peri > pistillate flower bracts; CCo, SnFrB or montane, < 3000 m

8. Upper 1/2 of peri purple-dotted, abaxially 1–3-veined, beak generally purple; peri stalks 0.1–0.2 mm ..... var. impressa

8' Upper 1/2 of peri generally green, abaxially generally 5–7-veined, beak generally green, tip purple; peri stalks 0.2–0.5 mm ..... var. lipocarpa

4' Plant rhizomed; peri veined or not

9. Leaf sheath fronts generally fibrous; lower sheaths generally scabrous

10. Peri ± soft, thin

11. Bladeless sheaths present on lower stem; peri 2.2–3.1 mm, 1.2–2 mm wide, weakly 1–3-veined adaxially on lower 1/2 ..... C. angustata

11' Bladeless sheaths 0 on lower stem; peri 3–4 mm, 2–2.2 mm wide, strongly 3–7-veined abaxially, adaxially ..... C. senta

10' Peri ± tough, thick

12. Peri generally red-spotted, faintly veined, dull, beak teeth bristly; pistillate flower bract  bristly; fruit 0 or lenticular, not indented ..... C. barbarae (2)

12' Peri generally not red-spotted, not veined, shiny, beak teeth 0 or minute, not bristly; pistillate flower bract awns generally ; fruit generally indented on 1–2 sides, like a bent beer can ..... C. obnupta

9' Leaf sheath fronts not fibrous (generally fibrous in Carex barbarae); lower sheaths generally not scabrous

13. Spikelets drooping or nodding (generally  when immature)

14. Longest spikelets 1.8–5 cm; fruit often indented on 1–2 sides, like a bent beer can; coastal salt marshes, freshwater intertidal zones ..... C. lyngbyei

14' Longest spikelets 4.55–11.5 cm; fruit not indented; coastal or inland, freshwater ..... C. aquatilis var. dives

13' Spikelets generally erect or ascending

15. Mature peri faces veined, walls tough or thick

16. Leaves green, generally not glaucous, sheath front red-dotted, generally dark copper or purple near tip, lower generally fibrous ..... C. barbarae (2)

16' Leaves generally blue-green, ± glaucous, sheath fronts generally white, occasionally sparse-red-dotted or ± coppery, lower not fibrous ..... C. nebrascensis

15' Mature peri faces not veined, walls delicate or thin

17. Leaf sheaths red-dotted or white; inflorescence bract generally > inflorescence; flower stem base spongy-thickened ..... C. aquatilis var. aquatilis

17' Leaf sheaths brown- or purple-dotted; inflorescence bract < inflorescence; flower stem base thin, not spongy-thickened ..... C. scopulorum var. bracteosa

Group 9: Stigmas 2; spikelets with staminate flowers above pistillate flowers

1. Plants rhizomed (loosely cespitose)

2. Inflorescence ovoid to open to dense; lowest  generally obvious at arm's length

3. Inflorescence 3–4 mm wide; lateral spikelets with 1–3 peri ..... C. disperma

3' Inflorescence > 5 mm wide; lateral spikelets with > 3 peri

4. Peri bulging, marginal veins occasionally not visible abaxially; pistillate flower bracts often with  > 1 mm, the bracts covering peri ..... C. tumulicola (2)

4' Peri not bulging, marginal veins visible abaxially; pistillate flower bracts with awns 0 or < 1 mm, the bracts < or > peri, covering peri or not ..... Group 7, couplet 12

2' Inflorescence spheric to ovoid, dense; lowest spikelets not obvious at arm's length

5. Spikelets generally pistillate ..... Group 7, couplet 12

5' Spikelets staminate/pistillate

6. Leaves inrolled, ± = stem, 0.5–1.5 mm wide; stem curved; peri ± not inflated, > pistillate flower bracts, beak indistinct, 0.4–0.9 mm; anthers 0.9–1.4 mm ..... C. incurviformis

6' Leaves flat, < stem, (1.5)2–3.5(4) mm wide; stem straight; peri not inflated, ± = pistillate flower bracts, beak distinct, 0.9–1.5 mm; anthers 1.5–2.8 mm ..... C. vernacula

1' Plants  to loosely so

7. Inflorescence branched, lower  or branches generally with > 1 ; spikelets often > 10

8. Leaf  faces red-dotted

9. Peri pale to medium brown

10. Peri, beak, pistillate flower  dull yellow-brown to medium- or red-brown; pistillate flower bract awns 0.5–2 mm; peri adaxial veins 0–5, abaxial 3–7; inflorescence often continuous, obvious bracts generally 0–few; flowering stems generally longer than leaves ..... C. densa

10' Peri, beak, pistillate flower bract dull yellow-green to pale gray-brown; pistillate flower bract awns to 3 mm; peri adaxial veins 0, abaxial 0–3; inflorescence often interrupted, obvious bracts often > few; flowering stems generally < leaves ..... C. vulpinoidea

9' Peri dark brown to black

11. Leaf sheath faces widely dark or coppery at top ..... C. cusickii

11' Leaf sheaths faces pale, not dark or coppery at top (narrowly copper-margined)

12. Peri 3–4.5 mm, 1.4–2.1 mm wide, beak 1–1.5 mm fruit 1–1.3 mm wide ..... C. alma

12' Peri 2–2.9 mm, 0.9–1.4 mm wide, beak 0.9–1.1 mm; fruit 0.7–1 mm wide ..... C. diandra

8' Leaf sheath faces white, not red-dotted

13. Peri widest near base, gradually narrowed to indistinct beak, length > 2 × width; sheath faces generally cross-wrinkled

14. Stem not winged, mid-stem generally <= 1.5 mm wide, not easily  between fingers; lower inflorescence branches < 1 cm ..... C. neurophora (2)

14' Stem wide-3-winged, mid-stem generally 2.5–7 mm wide, easily compressed between fingers; lower inflorescence branches generally 1–3+ cm ..... C. stipata var. stipata

13' Peri generally widest near middle, ± abruptly narrowed to distinct beak, length generally < 2 × width; sheath faces cross-wrinkled or not

15. Inflorescence open, lowest  generally 2+ × lowest spikelet ..... C. divulsa subsp. divulsa (2)

15' Inflorescence dense, lowest internode < lowest spikelet (see couplet 12)

7' Inflorescence not branched, lower nodes with 1 spikelet; spikelets generally < 10

16. Peri widest near base, gradually narrowed to indistinct beak

17. Peri beak pale or green; introduced weeds at low elevations

18. Spikelets densely clustered, indistinct at arm's length; inflorescence ; peri ovate ..... [C. leavenworthii]

18' Spikelets loosely clustered, at least lowest spikelets distinct at arm's length; inflorescence narrow-oblong; peri  ..... C. texensis

17' Peri beak dark brown; native, often montane

19. Leaf sheath front generally cross-wrinkled; peri beak  at least on 1 side ..... C. neurophora (2)

19' Leaf sheath front not cross-wrinkled; peri beak 

20. Peri adaxial veins 5–7; lower leaves generally overlapped and hiding sheaths; sheath mouth without thick rim ..... C. jonesii

20' Peri adaxial veins 7–12; lower leaves generally not overlapped and hiding sheaths; sheath mouth generally with thick rim ..... C. nervina

16' Peri widest near middle, often abruptly narrowed to distinct beak

21. Peri pale green or light brown; peri > pistillate flower bracts, easily visible

22. Inflorescence lowest internode generally 2+ × lowest spikelet ..... C. divulsa subsp. divulsa (2)

22' Inflorescence lowest internode <= lowest spikelet ..... C. vallicola

21' Peri center brown or copper, margins generally contrasting pale or green; peri >= pistillate flower bracts, often obscured

23. Inflorescence ovoid or spheric, 0.8–2 cm, 6–15 mm wide; lower spikelets generally not distinct ..... C. hoodii

23' Inflorescence oblong, 1.5–5 cm, 6–10 mm wide; lower spikelets ± distinct

24. Peri  to , beak 0.6–1.3 mm; pistillate flower bracts 3.4–4 mm, 1.6–2 mm wide; lower bracts generally < spikelets, inflorescence ..... C. occidentalis

24' Peri , beak 1.2–3 mm; pistillate flower bracts 4–5.2 mm, 2–2.8 mm wide; lower bracts > spikelets, often > inflorescence ..... C. tumulicola (2)

Group 10: Stigmas 2; spikelets with pistillate flowers above staminate flowers; peri not winged; stems generally solid

1. Inflorescence bracts >> inflorescence; plant rhizomed; < 100 m ..... C. inversa

1' Inflorescence bracts generally < inflorescence; plant  to loosely so; generally < 3500 m

2. Peri  or beak obvious,  outline jagged at arm's length

3. Staminate flower bracts inconspicuous in wide terminal spikelet

4. Pistillate flower bracts green, white, or light brown,  green or pale brown; inflorescence , or , >= 1.5 cm ..... C. arcta (2)

4' Pistillate flower bracts ± black, spikelets dark; inflorescence ovoid, <= 1.5 cm ..... C. illota

3' Staminate flower bracts obvious at narrowed base of terminal spikelet

5. Peri  to spreading, beak 15–40% peri length, peri attached at base ..... C. laeviculmis (2)

5' Peri widely spreading or reflexed, beak generally 20–85% peri length, peri attached near base abaxially

6. Lower peri in spikelet ± abruptly narrowed to short beak, margin with slight bulge or shoulder; beak 0.4–0.95, 18–44% length of body, peri generally 1.9–3.3 mm, length 1–2(2.2) × width ..... C. interior

6' Lower peri in spikelet more gradually narrowed to longer beak, margin without bulge or shoulder; beak 0.95–2 mm, 35–86% length of body, peri generally 2.9–4.75 mm, length 1.7–3.6 × width ..... C. echinata

7. Peri generally 2.9–4 mm, veins generally 0 over fruit adaxially; widest leaves generally 0.7–2.7 mm wide; inflorescence open to dense; KR, NCoRO, CaRH, SNH, SnBr, < 3200 m ..... subsp. echinata

7' Peri generally 3.5–4.75 mm, veins 2–12 over fruit adaxially; widest leaves generally 1.7–3.8 mm wide; inflorescence dense; NCo, CCo, < 200 m ..... subsp. phyllomanica

2' Peri ascending or beak inconspicuous, spikelet outline generally smooth at arm's length

8. Peri beak 0–0.5 mm; peri widest near middle

9. Peri fleshy; terminal spikelet generally obviously staminate at base, some terminal spikelets entirely staminate (see Group 8, couplet 2)

9' Peri not fleshy; terminal spikelet inconspicuously staminate at base, not entirely staminate

10. Peri beak abaxial flap pale, non-contrasting, not reaching to just below base of beak; stem generally , (10)30–90 cm ..... C. canescens subsp. canescens

10' Peri beak abaxial flap dark, contrasting, reaching to just below base of beak; stems generally leaning at 45° angle, 10–30 cm ..... C. praeceptorum

8' Peri beak generally 0.5–2.5 mm; peri widest below middle or near base

11. Inflorescence straight; spikelets clustered, lowest > lowest  ..... C. arcta (2)

11' Inflorescence generally bent at lowest spikelet; spikelets separated, lowest generally < lowest internode

12. Peri beak 15–38% peri length (beak measured from fruit top, on peri from middle of spikelet)

13. Peri ascending or spreading, 2.3–3.7 mm, beak occasionally ; leaves 0.9–2.3 mm wide ..... C. laeviculmis (2)

13' Peri erect or ascending, 2.8–4.5 mm, beak not recurved; leaves 2.4–5.9 mm wide ..... C. leptopoda

12' Peri beak 39–53% peri length (beak measured from fruit top, on peri from middle of spikelet)

14. Peri beak teeth prominent, 0.2–1 mm; mid-stem glabrous or ± scabrous at 20× ..... C. bolanderi

14' Peri beak teeth not prominent, 0–0.2(0.4) mm; mid-stem  at 20× ..... C. infirminervia

Group 11: (sect. Ovales) Stigmas 2; spikelets with pistillate flowers above staminate; peri winged; stem hollow. Inflorescence bracts generally elongate on first flush of growth of some species, but other species sporadically produce elongate inflorescence bracts on late season shoots (e.g., C. fracta, C. specifica, C. subfusca). Late season shoots often with atypically elongate or compact inflorescence, and/or atypically shaped peri. Peri beak shape variable in some species (e.g., C. fracta, C. preslii, C. subfusca), ± uniform, important in others, e.g., C. specifica (see illustration), with beak margin either ± flat and serrate or ± so, except tip entire 0–0.3 mm, or e.g., C. abrupta (see illustration), beak tips ± cylindric, tip entire for >= 0.4 mm. [Note: For keying, use subbasal peri in mature spikelets from first flush of growth; avoid peri from upper 1/2 of spikelet, they are narrow and not diagnostic; similarly basal-most peri are occasionally malformed; use ripe peri, immature peri generally do not show critical ventral veins]

1. Leaf  front green ± to top, white-translucent triangular area extending < 6 mm below top ..... Group 11A

1' Leaf sheath front with extensive white-translucent zone extending > 10 mm below top

2. Contraligule 3–13 mm ..... Group 11B

2' Contraligule 0–2 mm

3. Peri margin  and marginal wings 0 or < 0.2 mm wide ..... Group 11C

3' Peri margin minute-serrate, especially upper body or beak base or marginal wings generally > 0.2 mm wide

4. Pistillate flower bracts uniformly covering and ± obscuring peri; peri generally with strong abaxial veins ..... Group 11D

4' Pistillate flower bracts < or narrower than peri, peri easily visible; peri with strong abaxial veins or not

5. Larger peri 6–9.3 mm ..... Group 11E

5' Larger peri < 6 mm

6. Inflorescence  obvious, > inflorescence ..... Group 11F

6' Inflorescence bract inconspicuous, < inflorescence

7. Peri beak tip broadly winged and flattened, minute-serrate throughout or ± so (cylindric entire tip <= 0.3 mm), generally pale or only slightly darkened ..... Group 11G

7' Peri beak tip , entire >= 0.4 mm, often darkened or ± black ..... Group 11H

Group 11A: Leaf sheath front green ± to top

1. Peri gradually narrowed to indistinct beak, generally pistillate flower  tip  to short-awned ..... C. scoparia var. scoparia

1' Peri abruptly narrowed to distinct beak,  to ± round to obovate or widely ; pistillate flower bract tip blunt to 

2. Peri body widest at or below middle; vegetative stems not leaning or branching or rooting at  ..... C. feta

2' Peri body widest above middle; vegetative stems occasionally leaning or branching or rooting at nodes ..... C. longii

Group 11B: Ligules long, sleeve-like

1. Inflorescence generally short, generally ± dense, ± head-like ..... C. pachycarpa

1' Inflorescence  to , dense or not, not head-like

2. Peri wings generally 0.1–0.25 mm wide at mid-body; contraligule generally 5–13 mm; inflorescence often ±white or green (pale brown); peri abruptly narrowed to distinct beak ..... C. fracta

2' Peri wings generally 0.3–0.5 mm wide at mid-body; contraligule generally 1–5 mm; inflorescence green or light- to rusty-brown; peri abruptly or gradually narrowed to beak

3. Peri adaxial veins generally 1–6, 0 exceeding fruit; peri ovate to narrow-ovate, 3.7–5.5 mm, walls translucent to opaque ..... C. multicostata

3' Peri adaxial veins generally 6–10, >= 3 exceeding fruit; peri generally , 4.9–6.6 mm, walls generally translucent ..... C. specifica

Group 11C: Peri marginal wings entire (generally 0 in Carex illota)

1. Peri margins sharp-edged but not winged at mid-body; pistillate flower bracts and  dark brown to ± black; inflorescence dense, length <= 2 × width, often wider than long; peri gradually narrowed to indistinct beak (beak base occasionally winged ± 0.1 mm); peri base with spongy or pithy interior around fruit ..... C. illota

1' Peri , margins winged <= 0.2 mm at mid-body; pistillate flower bracts and spikelets pale to dark brown; inflorescence often ± open, length 3+ × width; peri abruptly or gradually narrowed to ± distinct beak; peri base without spongy or pithy interior around fruit

2. Peri wings often inrolled, beak generally with inconspicuous flap; fruit generally 1.7–2.3 mm, generally 1.1–1.5 mm wide; < 850 m ..... C. gracilior

2' Peri wings flat, beak with obvious white-margined flap; fruit 1.1–1.4 mm, 0.7–1 mm wide; 1000–3400 m ..... C. integra

Group 11D: Peri covered by pistillate flower bracts; peri abaxially strongly 3–14-veined

1. Inflorescence ± bent, flexible, or nodding

2. Peri  generally 0.1–0.2 mm wide, inrolled, not visible in abaxial view; peri generally without adaxial veinsmargins often  above widest point ..... C. gracilior (2)

2' Peri wing generally 0.2–0.6 mm wide, flat, visible in abaxial view; peri often with strong adaxial veins, margins  above widest point

3. Peri beak tip brown,  and entire > 0.4 mm, or flat and entire < 0.4 mm; peri generally ± flat except over fruit, body generally wide-elliptic ..... C. leporina (2)

3' Peri beak tip white, generally cylindric, entire > 0.4 mm; peri generally ± planoconvex, body generally narrow-elliptic ..... C. praticola

1' Inflorescence straight, stiff, 

4. Longer peri 6–8.1 mm

5. Inflorescence open; peri beak with obvious white abaxial flap; peri walls thick, opaque ..... C. petasata

5' Inflorescence dense; peri beak with inconspicuous abaxial flap; peri walls thin, ± translucent ..... C. specifica

4' Longer peri < 6 mm

6. Peri 0.8–1.2 mm wide, beak indistinct, wings generally incurved ..... C. leporinella

6' Peri 1.3–2.6 mm wide, beak distinct or not, wings not incurved

7. Peri generally widest near or above middle; inflorescence generally dense,  overlapped;   mouth white; subalpine to alpine, 2500–4000 m

8. Strong adaxial peri veins generally 0(4); peri walls thin, ± translucent ..... C. phaeocephala

8' Strong adaxial peri veins 3–8; peri walls thick, opaque ..... C. tahoensis

7' Peri generally widest below middle; inflorescence dense or open, spikelets overlapped or not; leaf sheath mouth occasionally brown-tinged; coastal, montane, 0–3500 m

9. Peri adaxial veins generally reaching beak base; peri walls sometimes thin, ± translucent

10. Peri not shiny at 10×, beak tip ± flat, serrate; inflorescence elongate, generally open, green or gold; montane, 800–3500 m ..... Group 11B, couplet 2

10' Peri ± shiny at 10×, beak tip cylindric, entire; inflorescence ovoid, dense, generally brown or coppery; coastal, insular, or montane, < 900 m ..... C. harfordii

9' Peri adaxial veins 0 or generally reaching at most to fruit tip; peri walls generally ± thick, opaque

11. Well-developed peri with wing at mid-body generally 0.4–0.6 mm wide ..... C. leporina (2)

11' Well-developed peri with wing at mid-body <= 0.4 mm wide

12. Inflorescence generally open, lower spikelets distinct; peri wings generally 0.1–0.2 mm wide at mid-body, generally inrolled, not visible abaxially, margins at 16× entire from base to above widest point; peri upper body entire or not, beak minute-serrate; leaf blades 1.2–3 mm wide ..... C. gracilior (2)

12' Inflorescence ± dense (except on late season stems), lower spikelets often clustered or overlapped, indistinct; peri wings generally 0.2–0.3(0.4) mm wide at mid-body, flat, visible abaxially, margins at 16× entire from base to ± widest point; peri upper body, most of beak minute-serrate; leaf blades 1.3–4.6 mm wide ..... C. subbracteata

Group 11E: Larger peri 6–9.3 mm

1. Inflorescence ±  (elliptic, triangular), dense, head-like

2. Pistillate flower bracts generally dark brown to ± black; peri flat except over fruit ..... C. haydeniana

2' Pistillate flower bracts light brown or red-brown; peri planoconvex ..... C. pachycarpa

1' Inflorescence  to , dense or not, not head-like

3. Inflorescence bent or flexed at lower , curved ..... C. praticola

3' Inflorescence straight

4. Peri base abruptly narrowed to stalk 0.5–1 mm (measured below fruit base); inflorescence generally dense, elliptic,  (4)6–14; peri margin crinkled or flat; pistillate flower bracts green to light brown or red-brown ..... C. specifica

4' Peri base abruptly narrowed to stalk 1–2 mm (measured below fruit base); inflorescence open, oblong, spikelets 1–7; peri margin flat; pistillate flower bracts red-brown

5. Translucent pistillate flower  margins <= 0.4 mm; peri beak abaxial flap inconspicuous ..... C. davyi

5' Translucent pistillate flower bract margins generally > 0.4 mm wide; peri beak abaxial flap obvious ..... C. petasata

Group 11F: Inflorescence bract generally 2–3 × inflorescence

1. Inflorescence ± lateral, lowest  wide, leaf-like, , appearing to be continuation of stem; most peri beaks flat, winged, minute-serrate (cylindric, unwinged,  portion < 0.4 mm) ..... C. unilateralis

1' Inflorescence ± terminal, lowest bract often narrower, less leaf-like,  or , not appearing to be continuation of stem; peri beaks ± flat or  (unwinged, entire portion > 0.4 mm)

2. Peri adaxial veins exceeding fruit top

3. Contraligule generally 5–13 mm; inflorescence 2.5–8 cm, generally ± white or green (to pale brown) ..... C. fracta

3' Contraligule 0 or < 3 mm; inflorescence 1.5–4 cm, generally dark brown or ± black ..... C. harfordii

2' Peri adaxial veins 0 or not exceeding fruit top

4. Peri base abruptly narrowed to distinct stalk (on dried material often bent or crumpled); peri strongly flattened except over fruit, or occasionally biconvex ..... C. athrostachya

4' Peri stalk indistinct or 0; peri planoconvex

5. Peri generally 3.5–4.7(5.7) mm; inflorescence coarse, parts large at arm's length; < 900 m ..... C. subbracteata

5' Peri generally 2.3–3.5 mm; inflorescence fine, parts small at arm's length; (75)700–3800 m ..... C. subfusca

Group 11G: Peri beak wide-winged, minute-serrate; tip cylindric, entire < 0.4 mm

1. Inflorescence bent or flexed at lowest  ..... C. scoparia var. scoparia (2)

1' Inflorescence , not bent or flexed at lowest node

2. Widest peri 2.2–3.4 mm wide

3. Peri wide-ovate or -elliptic or ± round, winged margin generally 0.5–1 mm wide ..... C. straminiformis

3' Peri  to , winged margin generally 0.3–0.5 mm wide

4. Inflorescence dense, ± spheric, 10–22 mm; peri 4.9–5.9(6) mm ..... C. pachycarpa (2)

4' Inflorescence open, linear-oblong, 20–60 mm; peri (5.7)6–8.1 mm ..... C. petasata (2)

2' Widest peri <= 2.1 mm wide

5. Wider peri wings generally 0.1–0.3 mm at midbody

6. Inflorescence 2.5–8 cm; contraligule generally 5–13 mm; peri adaxial veins exceeding fruit generally >=3 ..... C. fracta

6' Inflorescence 1.1–3 cm; contraligule generally < 3 mm; peri adaxial veins generally 0 or not exceeding fruit ..... C. subfusca

5' Wider peri wings generally 0.3–0.5 mm at midbody

7. Inflorescence ± ovate (elliptic, triangular), ± head-like

8. Peri thick, planoconvexabaxial veins 8–17, wide, tissue often sunken between veins; adaxial veins 0–12; individual  generally indistinct at arm's length ..... C. pachycarpa (2)

8' Peri thin, flat, abaxial veins 0–8, thin, tissue not sunken between veins; adaxial veins 0–5; individual spikelets distinct at arm's length ..... C. scoparia var. scoparia (2)

7' Inflorescence , lanceolate, or , generally not head-like

9. Inflorescence generally open, linear-oblong, spikelets distinct at arm's length ..... C. petasata (2)

9' Inflorescence often dense, elliptic to lanceolate or oblanceolate, at least upper spikelets indistinct at arm's length

10. Peri adaxial veins exceeding fruit; peri generally 4.9–6.6 mm, generally lanceolate ..... C. specifica

10' Peri adaxial veins generally shorter, not exceeding fruit or 0; peri 3.3–5.5 mm, generally ovate

11. Peri generally gradually narrowed to indistinct beak, adaxial veins obvious, (1)3–13; peri walls translucent to opaque ..... C. multicostata

11' Peri abruptly narrowed to distinct beak, adaxial veins 0 (3, inconspicuous); peri walls opaque ..... C. preslii

Group 11H: Peri beak tip generally cylindric, generally entire >= 0.4 mm

1. Peri flat, thin except over fruit (± inflated, convex both faces)

2. Peri wide-elliptic to ± round, margins occasionally crinkled or ruffled, beak distinct, 20–25% of total peri length; anthers early-deciduous to persistentpistillate flower bracts 1/2 peri width

3. Peri beak <= 1.2 mm; leaves generally 0.5–2.7 mm wide when flat, in life generally folded or channeled toward base; inflorescence dense to more open, or  ..... C. proposita

3' Peri beak generally 1.2–1.5 mm; leaves (1.7)3–4 mm wide when flat, in life flat or folded; inflorescence generally dense, ovate ..... C. straminiformis

2' Peri ovate to , margins generally flat, beak indistinct or > 25% of total peri length; anthers generally deciduous; pistillate flower bracts > 1/2 peri width

4. Most peri distinctly short-stalked, dried stalks often bent or crumpled; inflorescence  on some heads long-awned, wide at base ..... C. athrostachya

4' Most or all peri not distinctly stalked; inflorescence bract rarely long-awned or wide at base

5. Peri 4–6.5 mm, (2.3)2.6–4.2 mm beak tip to fruit; peri green, dark brown, or coppery, margins often darker than wingsstem 9–20(40) cm; subalpine to alpine ..... C. haydeniana

5' Peri (2.8)3.4–4.5(5.2) mm, 1.5–2.5(2.8) mm beak tip to fruit; peri green to light brown, center often brown, margin color generally same as wings; stem 20–110 cm; montane to alpine ..... C. microptera

1' Peri generally planoconvex, thick

6. Peri adaxial veins generally 3–10, generally exceeding fruit

7. Inflorescence elongated, oblong to elliptic, not head-like, lower  generally distinct, bases generally ; montane

8. Peri 2.5–4.8(5.3) mm ..... C. mariposana

8' Peri (5.7)6–8.5 mm ..... C. petasata

7' Inflorescence compact, often ovoid, head-like, lower spikelets indistinct, bases generally blunt; coastal or montane

9. Peri margins  from base to ± widest point, minute-serrate on beak and upper body; stems , not branched at  face tops generally pale; generally without leaf-like inflorescence bract; 1200–3450 m ..... C. abrupta

9' Peri margins entire from base often to above widest point, minute-serrate on beak and occasionally uppermost body; stems often leaning, occasionally branched at nodes, branches leafy or fertile; sheath face tops often brown-tinged; inflorescence bract occasionally leaf-like; < 900 m ..... C. harfordii

6' Peri adaxial veins 0 or short, 0 (1) exceeding fruit

10. Peri margins at 16× entire from base to above widest point; marginal wings at mid-body often inrolled so not visible from abaxial side ..... C. gracilior

10' Peri margins at 16× entire from base to ± widest point; marginal wings at mid-body generally not inrolled, visible from abaxial side

11. Pistillate flower bracts generally 4.2–5.8 mm, ± hiding peri

12. Inflorescence generally open, often bent or flexed at lowest , most spikelets distinct at arm's length ..... C. praticola

12' Inflorescence generally dense, erect, most spikelets indistinct at arm's length ..... C. subbracteata (2)

11' Pistillate flower bracts generally < 4.2 mm, not hiding peri

13. Peri generally 2.3–3.5 mm,  margin at midbody generally 0.1–0.25 mm wide; inflorescence at arm's length fine-textured, parts small ..... C. subfusca

13' Peri generally >= 3.5 mm, wing margin at midbody generally 0.3–0.4 mm wide; inflorescence at arm's length coarse-textured, parts large

14. Peri  ± star-shaped, outline jagged at arm's length; pistillate flower bract dark throughout, or white margins narrow, < 0.1 mm wide ..... C. pachystachya

14' Peri ± ; spikelet not star-shaped, outline ± smooth at arm's length; pistillate flower bract generally with white margins 0.2–0.5 mm wide

15. Peri beaks of 2 kinds in an inflorescence, some ± flat, with smooth entire part < 0.4 mm, some , with smooth entire part > 0.4 mm; generally dry soil; 1800–3400 m, KR, NCoR, CaRH, SNH, SnJt ..... C. preslii

15' Peri beaks of 1 kind, generally cylindric, smooth entire part > 0.4 mm; seasonally wet soil; < 900 m, NCo, NCoRO, CW, SCo, n ChI, WTR ..... C. subbracteata (2)


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