Plants cespitose or not, short to long rhizomatous. Culms brown or red-brown at base. Leaves: basal sheaths fibrous or not; sheath fronts sometimes dotted purple or red, sometimes prominently veined proximally and becoming ladder-fibrillose, membranous; blades V-shaped or M-shaped in cross section when young, glabrous, sometimes papillose. Inflorescences racemose, with 2–8(–10) spikes; proximal bracts scalelike or leaflike, sheathless or short-sheathing; lateral spikes pistillate, occasionally androgynous, or the distal 1–3 staminate, pedunculate or subsessile, prophyllate, at least 2 times as long as wide; terminal spikes staminate or, rarely, gynecandrous. Proximal pistillate scales with apex obtuse to acuminate or, at least the proximal, long-awned. Perigynia erect or ascending, rarely spreading, veined or veinless on faces, with 2 prominent marginal veins, sessile or stipitate, elliptic to ovate or obovate, plano-convex or biconvex in cross section, base rounded or tapering, apex rounded or tapering to beak or not, usually papillose or, sometimes, smooth; beak orifice entire, emarginate, or shallowly bidentate. Stigmas 2. Achenes biconvex, smaller than bodies of perigynia; style deciduous. x = 27–48.

Distribution

Worldwide.

Discussion

Species 70–90 (31 in the flora).

Carex sect. Phacocystis, while fairly cohesive, contains several distinct groups of species. Members of the Carex acuta group (C. lenticularis, C. nigra, C. rufina, and C. eleusinoides) are slender, cespitose plants that have amphistomatous leaves, bracts longer than the inflorescences, veined, stipitate perigynia distended by the base of the achenes, and chromosome numbers of 2n = 82–86. Members of the C. stricta group (C. schottii, C. senta, C. nudata, and C. angustata) are moderately robust plants with hypostomatous leaves and have scabrous, ladder-fibrillose proximal sheaths, bracts shorter than the inflorescence, and veined perigynia. Several additional groups of two or three species show strong morphologic, anatomical, and chromosomal similarities. This section was previously separated into two sections. Species formerly placed in sect. Cryptocarpae have three-veined, awned scales, pendent spikes, and large achenes that in many species are constricted. Species formerly placed in sect. Acutae have one-veined scales, erect spikes, and smaller achenes that are not constricted. The distinctions do not hold up when variation among all species is considered.

Among the most common groups of wetland sedges in North America, species of sect. Phacocystis usually occur in wetlands, on shores, marshes, or wet tundra.

Selected References

Cayouette, J. and P. Morisset. 1985. Chromosome studies on natural hybrids between maritime species of Carex (sections Phacocystis and Cryptocarpae) in northeastern North America, and their taxonomic implications. Canad. J. Bot. 63: 1957–1982.

Cayouette, J. and P. Morisset. 1986. Chromosome studies on Carex paleacea Wahl., C. nigra (L.) Reichard, and C. aquatilis Wahl. in northeastern North America. Cytologia 51: 857–883.

Cayouette, J. and P. Morisset. 1986b. Chromosome studies on the Carex salina complex (Cyperaceae, section Cryptocarpae) in northeastern North America. Cytologia 51: 817–856.

Faulkner, J. S. 1973. Experimental hybridization of north-west European species in Carex section Acutae (Cyperaceae). Bot. J. Linn. Soc. 67: 233–253.

Standley, L. A. 1983. A clarification of the status of Carex crinita and C. gynandra (Cyperaceae). Rhodora 85: 229–241.

Standley, L. A. 1985. Systematics of the Acutae group of Carex (Cyperaceae) in the Pacific Northwest. Syst. Bot. Monogr. 7: 1–106.

Standley, L. A. 1987. Anatomical and chromosomal studies of Carex section Phacocystis in eastern North America. Bot. Gaz. 148: 507–518.

Standley, L. A. 1990. Allozyme evidence for the hybrid origin of the maritime species Carex salina and Carex recta (Cyperaceae) in eastern North America. Syst. Bot. 15: 182–191.

Lower Taxa

Carex angustata, Carex aperta, Carex aquatilis, Carex barbarae, Carex bigelowii, Carex crinita, Carex eleusinoides, Carex emoryi, Carex endlichii, Carex gynandra, Carex haydenii, Carex interrupta, Carex lenticularis, Carex lyngbyei, Carex mitchelliana, Carex nebrascensis, Carex nigra, Carex nudata, Carex obnupta, Carex paleacea, Carex ramenskii, Carex recta, Carex rufina, Carex salina, Carex schottii, Carex scopulorum, Carex senta, Carex stricta, Carex subspathacea, Carex torta, Carex vacillans

Key

1	Pistillate scales with prominent, scabrous awn on at least the proximal scales.	> 2
1	Pistillate scales with apex acute, acuminate, or mucronate, lacking prominent, scabrous awn.	> 13
2	Leaf blades involute, 1–2 mm wide.	Carex subspathacea
2	Leaf blades not involute, the widest more than 2 mm wide.	> 3
3	Perigynia veinless.	> 4
3	Perigynia veined.	> 7
4	Spikes usually erect; proximal sheaths not ladder-fibrillose.	Carex recta
4	Spikes usually pendent; proximal sheaths ladder-fibrillose.	> 5
5	Sheaths glabrous; perigynia obovoid; apex of pistillate scales retuse.	Carex crinita
5	Sheaths scabrous; perigynia broadly ovoid to ellipsoid; apex of pistillate scales truncate to acuminate.	> 6
6	Perigynia ovoid to ellipsoid, not papillose over surface; achenes constricted; apex of pistillate scales acuminate.	Carex gynandra
6	Perigynia ovoid, papillose over entire surface; achenes not constricted; apex of pistillate scales truncate.	Carex mitchelliana
7	Proximal bract often spathelike, enclosing spike; achenes glossy, deeply constricted on 1 edge.	Carex salina
7	Proximal bract not spathelike, not enclosing spike; achenes not glossy, constricted or not.	> 8
8	Beak of perigynium bidentate, apical teeth to 0.5 mm; achenes not constricted.	> 9
8	Beak of perigynium entire, apical teeth not more than 0.3 mm; achenes constricted on 1 or both edges.	> 10
9	Sheaths ladder-fibrillose; proximal bract much longer than inflorescence.	Carex barbarae
9	Sheaths not ladder-fibrillose; proximal bract equaling inflorescence.	Carex nebrascensis
10	Perigynia thick-walled, leathery.	> 11
10	Perigynia thin-walled, not leathery.	> 12
11	Spikes pendent, 5–13 mm thick.	Carex paleacea
11	Spikes erect, 4–7 mm thick.	Carex ramenskii
12	Scales dark purple-brown.	Carex vacillans
12	Scales brown to reddish brown.	Carex recta
13	Proximal bract longer than inflorescence (usually at least 1.5 times as long).	> 14
13	Proximal bract shorter than or equal to inflorescence.	> 22
14	Sheaths ladder-fibrillose.	> 15
14	Sheaths not ladder-fibrillose.	> 16
15	Widest leaf blades not more than 7 mm wide; perigynia veinless on faces.	Carex obnupta
15	Widest leaf blades 10–15 mm wide; perigynia 5–7-veined on faces.	Carex schottii
16	Spikes pendent; perigynia yellow-brown, thick-walled, indistinctly veined; scales longer than perigynia, apex acuminate.	Carex lyngbyei
16	Spikes erect or pendent; perigynia green, pale brown, red- or purple-brown, thin-walled, veinless or veined; scales shorter or longer than perigynia, apex not acuminate.	> 17
17	Perigynia veinless; achenes glossy.	Carex aquatilis
17	Perigynia veined; achenes dull.	> 18
18	Terminal spike staminate.	Carex lenticularis
18	Terminal spike gynecandrous.	> 19
19	Scales reddish brown, pale; body and beak of perigynium pale green or pale brown.	Carex lenticularis
19	Scales purple-brown or black; beak of perigynium reddish brown or black, darker than bodies.	> 20
20	Perigynia 5–7-veined on each face, ovoid; stipe to 0.5 mm.	Carex lenticularis
20	Perigynia 3–5-veined on each face, ellipsoid; stipe not more than 0.2 mm.	> 21
21	Perigynia prominently veined, apex acute; basal sheaths brown.	Carex rufina
21	Perigynia indistinctly veined, apex round; basal sheaths reddish brown.	Carex eleusinoides
22	Proximal sheaths ladder-fibrillose.	> 23
22	Proximal sheaths not ladder-fibrillose.	> 28
23	Scales pale red-brown.	> 24
23	Scales dark red-brown or black.	> 25
24	Scales longer than perigynia; perigynia olive-green, veinless, inflated, obovoid.	Carex haydenii
24	Scales shorter than or equaling perigynia; perigynia pale brown, 0–5-veined on each face, not inflated, ovoid.	Carex stricta
25	Perigynia veinless.	Carex scopulorum
25	Perigynia veined.	> 26
26	Perigynia 1–3-veined on each face.	Carex angustata
26	Perigynia 3–9-veined on each face.	> 27
27	Perigynia broadly ellipsoid or ovoid, 2–2.2 mm wide, somewhat thick-walled and leathery; scales red-brown; plants not cespitose.	Carex senta
27	Perigynia narrowly ovoid or ellipsoid, 1.2–1.8 mm wide, thin-walled and leathery; scales red-brown; plants cespitose.	Carex nudata
28	Perigynia veined.	> 29
28	Perigynia veinless.	> 30
29	Scales black; perigynia with purple-brown spots distally; apex of proximal sheaths truncate.	Carex nigra
29	Scales pale red-brown; perigynia green; apex of proximal sheaths prolonged.	Carex emoryi
30	Perigynia with apex tapering, flat, triangular, twisted; beak orifice obliquely bidentate.	> 31
30	Perigynia with apex round or acute, not twisted; beak orifice obliquely bidentate or entire.	> 32
31	Perigynia orange-brown, obovoid; scales black.	Carex endlichii
31	Perigynia green, ovoid; scales red- to purple-brown.	Carex torta
32	Perigynia distended by achenes, fragile, often splitting; beak obliquely bidentate.	Carex interrupta
32	Perigynia not distended or split by achenes; beak orifice entire.	> 33
33	Perigynia inflated, obovoid; scales longer than perigynia, apex acute or acuminate.	Carex aperta
33	Perigynia flat, ellipsoid or obovoid; scales shorter than or equaling perigynia, apex acute or obtuse.	> 34
34	Leaf blades 3.5–5 mm wide; pistillate spikes 4–5 mm thick; perigynia ellipsoid or obovoid, 2.5–4 mm.	Carex scopulorum
34	Leaf blades 2–3.5 mm wide; pistillate spikes 3–4 mm thick; perigynia ellipsoid, 2–3 mm.	Carex bigelowii