Plants loosely or densely cespitose, sometimes long rhizomatous or stoloniferous; roots brown or black without yellow-brown felty covering. Culms purple or red at base. Leaves: basal sheaths usually fibrous; sheath fronts membranous, mouth entire, proximal leaves, often dotted or tinged red or purple, rarely prominently veined and becoming ladder-fibrillose, glabrous; blades V-shaped in cross section when young, smooth or papillose. Inflorescences racemose, with 1–10 spikes; proximal bracts threadlike or, rarely, scalelike, sheathless, abaxial surface papillose; lateral spikes pistillate, rarely, gynecandrous with few staminate flowers, pedunculate, prophyllate; terminal spike gynecandrous with few perigynia, staminate, or pistillate. Proximal pistillate scales brown or black, not ciliate, apex obtuse to shortly awned. Perigynia erect or ascending, veined or veinless on faces, with 2 distinct marginal veins, sessile, obovoid to suborbicular, rounded or somewhat compressed in cross section, base cuneate to ± rounded, apex tapering or rounded to beak or rarely beakless, smooth or papillose, glabrous; beak entire or shortly bidentate. Stigmas 2–3. Achenes trigonous, smaller than to almost filling bodies of perigynia; style deciduous.

Distribution

Dry plains, wetlands, arctic, alpine tundras in North America and Eurasia.

Discussion

Species ca. 60 (29 species in the flora).

Selected References

Hermann, F. J. 1968. Notes on Rocky Mountain carices. Rhodora 70: 419–421.

Kalela, A. 1944. Systematische und Pflanzengeographische Studien an der Carex Subsektion Alpinae Kalela. Ann. Bot. Soc. Zool.-Bot. Fenn. “Vanamo” 19(3).

Murray, D. F. 1969. Taxonomy of Carex sect. Atratae (Cyperaceae) in the southern Rocky Mountains. Brittonia 21: 55–76.

Lower Taxa

Carex aboriginum, Carex adelostoma, Carex albonigra, Carex atrata, Carex atratiformis, Carex atrosquama, Carex bella, Carex buxbaumii, Carex chalciolepis, Carex epapillosa, Carex gmelinii, Carex hallii, Carex helleri, Carex heteroneura, Carex holostoma, Carex idahoa, Carex media, Carex mertensii, Carex nelsonii, Carex norvegica, Carex nova, Carex parryana, Carex pelocarpa, Carex raynoldsii, Carex sabulosa, Carex serratodens, Carex specuicola, Carex stevenii, Carex stylosa

Key

1	Terminal spike staminate (or androgynous in C. adelostoma).	> 2
1	Terminal spike gynecandrous (or wholly pistillate in C. parryana, C. hallii, and C. idahoa).	> 10
2	Lateral spikes always present, all spikes of similar length.	> 3
2	Lateral spikes absent, or mostly much shorter than terminal spike as long as terminal in C. parryana (C. hallii and C. idahoa can have single, terminal, staminate spike) [See also the key to unispicate Carex].	> 6
3	Leaves 3–7 mm wide; perigynia smooth; culms smooth or nearly so.	Carex raynoldsii
3	Leaves 1.5–4 mm wide; perigynia papillose; culms scabrous.	> 4
4	Perigynia distinctly beaked, veinless.	Carex stylosa
4	Perigynia beakless or minutely beaked.	> 5
5	Perigynia brown, obscurely veined; arctic.	Carex holostoma
5	Perigynia pale green, veinless; subarctic.	Carex adelostoma
6	Perigynia 3–6.6 × 1.2–3.4 mm; beak veined, 0.5–1 mm.	> 7
6	Perigynia 2–3 × 2–2.5 mm; beak veinless, minute to 0.2 mm.	> 8
7	Perigynia (2–)3–5 × 1.2–2 mm.	Carex serratodens
7	Perigynia (4.7–)5–6.6 × 2.2–3.4 mm.	Carex aboriginum
8	Pistillate scales dark brown to black, mostly exceeding perigynia.	Carex idahoa
8	Pistillate scales light to dark brown, shorter than, equaling, or only barely exceeding perigynia.	> 9
9	Lateral spikes much shorter than terminal spike.	Carex hallii
9	Lateral spikes (1 or more) as long as terminal spike.	Carex parryana
10	Lateral spikes sessile or short-pendunculate; spikes, at least proximal, sometimes separate and distinct; distal spikes forming dense terminal cluster.	> 11
10	Lateral spikes pedunculate; spikes contiguous or separate; distal spikes not forming a dense terminal cluster.	> 18
11	Achenes nearly filling body of perigynia.	> 12
11	Achenes filling proximal 1/2 or less of perigynia.	> 14
12	Plants with long-creeping rhizomes; perigynia 4–5 mm; beak 0.6–0.8 mm; pistillate scales longer than perigynia; Yukon, Alaska.	Carex sabulosa
12	Plants without long-creeping rhizomes; perigynia 2–3.5 mm; beak 0.2–0.4 mm; pistillate scales; North America, Eurasia.	> 13
13	Perigynia green or golden brown, veinless; pistillate scales with hyaline margins, equaling or shorter than perigynia.	Carex norvegica
13	Perigynia dark brown to purple-black, often veined proximally; pistillate scales without hyaline margins, 1/2 as long as perigynia.	Carex media
14	Perigynia ovate or elliptic.	> 15
14	Perigynia obovate.	> 16
15	Perigynia ovate, abruptly beaked; pistillate scales dark brown to almost black with hyaline margins; beak 0.4–0.5 mm.	Carex nova
15	Perigynia elliptic, gradually beaked; pistillate scales blue-black with hyaline margins; beak 0.8–0.1 mm.	Carex nelsonii
16	Pistillate scales as wide as perigynia, usually shorter than or equaling perigynia; distal margins of perigynia papillose, frequently serrulate.	Carex nova
16	Pistillate scales narrower than perigynia, usually longer than perigynia; distal margins of perigynia smooth, not serrulate.	> 17
17	Perigynia dark brown to purple-black; pistillate scales attenuate and mucronate, more than to 2 times as long as perigynia.	Carex helleri
17	Perigynia glossy reddish brown; pistillate scales acute, equaling or barely exceeding perigynia.	Carex pelocarpa
18	Proximal lateral spikes spreading or pendent.	> 19
18	Proximal lateral spikes erect, not spreading or pendent.	> 24
19	Perigynia ovate.	> 20
19	Perigynia broadly elliptic or obovate.	> 21
20	Leaves basal and cauline; proximal leaves bladeless, reduced to sheaths; pistillate scales conspicuously shorter than perigynia.	Carex mertensii
20	Leaves all basal; proximal leaves with blades; pistillate scales equaling or exceeding perigynia.	Carex chalciolepis
21	Perigynia broadly elliptic, papillose.	Carex atratiformis
21	Perigynia obovate, smooth.	> 22
22	Pistillate scales as broad as perigynia.	Carex bella
22	Pistillate scales narrower than perigynia.	> 23
23	Terminal spike with 1/3–2/3 staminate flowers at base; perigynia light green; pistillate scales with midveins lighter colored than bodies.	Carex heteroneura
23	Terminal spike with fewer than 1/4 staminate flowers at base; perigynia brown with light colored margins; pistillate scales with midveins same color as bodies.	Carex epapillosa
24	Lateral spikes of varying lengths, mostly shorter than terminal spike (Carex hallii and C. idahoa can have a single, terminal spike).	> 25
24	Lateral spikes of similar length.	> 27
25	Pistillate dark brown to black, scales exceeding perigynia.	Carex idahoa
25	Pistillate scales light to dark brown, shorter than, equaling, or barely exceeding perigynia.	> 26
26	Lateral spikes much shorter than terminal spike.	Carex hallii
26	Lateral spikes (1 or more) as long as terminal spike.	Carex parryana
27	Perigynia ovate, gradually beaked; beak 0.5–1 mm, bidentate, teeth spreading.	> 28
27	Perigynia obovate or broadly elliptic, beakless, minutely beaked, or distinctly, abruptly beaked; beak 0.2–0.5 mm, teeth, when present, not spreading.	> 29
28	Perigynia (2–)3–5 × 1.2–2 mm.	Carex serratodens
28	Perigynia (4.7–)5–6.6 × 2.2–3.4 mm.	Carex aboriginum
29	Pistillate scales ovate or broadly lanceolate, apex blunt.	> 30
29	Pistillate scales lanceolate, apex acute to conspicuously long-mucronate.	> 31
30	Spikes short-oblong or cylindric, 3–4.5 mm wide; perigynia 2–2.5 mm; beak 0.2–0.25 mm.	Carex stevenii
30	Spikes oblong or elongate, 5–6 mm wide; perigynia 2.5–3.5 mm; beak 0.3–0.5 mm.	Carex atrosquama
31	Pistillate scales conspicuously long-mucronate.	> 32
31	Pistillate scales acute or short-mucronate.	> 33
32	Perigynia brown, smooth; beak longer than 0.2 mm.	Carex gmelinii
32	Perigynia gray-green, papillose; beak absent or less than 0.2 mm.	Carex buxbaumii
33	Perigynia gray-green, conspicuously papillose throughout; beak minute, less than 0.2 mm.	Carex adelostoma
33	Perigynia straw colored, dark brown, or black, conspicuously papillose along distal margins; beak greater than 0.2 mm.	> 34
34	Pistillate scales acute, dark brown or black to margins.	Carex atrata
34	Pistillate scales acute or short-mucronate, light to dark brown with hyaline margins.	> 35
35	Perigynia dark brown, almost black; pistillate scales equaling perigynia.	Carex albonigra
35	Perigynia straw colored; pistillate scales shorter than perigynia.	Carex specuicola