Flora of North America species comparison

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Carex aquatilis var. dives

Carex sect. Phacocystis
Photo is of parent taxon

Sitka sedge, water sedge
Habit Plants cespitose or not, short to long rhizomatous.
Culms

35–150 cm, angles scabrous.

brown or red-brown at base.
Leaves

basal sheaths leafless, usually red-brown;

blades epistomic, 5–18 mm wide, adaxially papillose.

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

peduncle of proximal spike to 11 cm;

proximal bract longer than inflorescence, 3–10 mm wide.

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.
Spikes

pendent or the terminal usually erect;

proximal 3–6 spikes pistillate, 4.5–11.5 cm × 4–7 mm, base attenuate;

terminal 2–4 spikes staminate.

Perigynia

pale brown, ellipsoid, 1.9–3.5 × 1–1.2 mm, apex acute or obtuse;

beak purple-brown, 0.3–0.4 mm, papery.

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.
Achenes

biconvex, smaller than bodies of perigynia;

style deciduous.
Pistillate

scales red-brown or purple-brown.

Proximal

pistillate scales with apex obtuse to acuminate or, at least the proximal, long-awned.
Stigmas

2.
x

= 27–48.
2n

= 72, 74, 78, 80.

Carex aquatilis var. dives

Carex sect. Phacocystis
Phenology Fruiting Jul–Aug.
Habitat Marshes, shallow water along shores
Elevation 0–900 m (0–3000 ft)
Distribution
from FNA
AK; CA; MT; OR; WA; BC
[BONAP county map]
Worldwide
Discussion

Carex aquatilis var. dives is the most robust variety of C. aquatilis and the only member to have pendent spikes, ellipsoid perigynia, and epistomic leaves. Carex aquatilis var. dives intergrades with var. aquatilis and does not appear to be distinct at the specific level. It may hybridize with C. lyngbyei.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

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.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
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.
C. 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.
C. recta
4. Spikes usually pendent; proximal sheaths ladder-fibrillose.
→ 5
5. Sheaths glabrous; perigynia obovoid; apex of pistillate scales retuse.
C. 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.
C. gynandra
6. Perigynia ovoid, papillose over entire surface; achenes not constricted; apex of pistillate scales truncate.
C. mitchelliana
7. Proximal bract often spathelike, enclosing spike; achenes glossy, deeply constricted on 1 edge.
C. 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.
C. barbarae
9. Sheaths not ladder-fibrillose; proximal bract equaling inflorescence.
C. nebrascensis
10. Perigynia thick-walled, leathery.
→ 11
10. Perigynia thin-walled, not leathery.
→ 12
11. Spikes pendent, 5–13 mm thick.
C. paleacea
11. Spikes erect, 4–7 mm thick.
C. ramenskii
12. Scales dark purple-brown.
C. vacillans
12. Scales brown to reddish brown.
C. 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.
C. obnupta
15. Widest leaf blades 10–15 mm wide; perigynia 5–7-veined on faces.
C. schottii
16. Spikes pendent; perigynia yellow-brown, thick-walled, indistinctly veined; scales longer than perigynia, apex acuminate.
C. 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.
C. aquatilis
17. Perigynia veined; achenes dull.
→ 18
18. Terminal spike staminate.
C. lenticularis
18. Terminal spike gynecandrous.
→ 19
19. Scales reddish brown, pale; body and beak of perigynium pale green or pale brown.
C. 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.
C. 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.
C. rufina
21. Perigynia indistinctly veined, apex round; basal sheaths reddish brown.
C. 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.
C. haydenii
24. Scales shorter than or equaling perigynia; perigynia pale brown, 0–5-veined on each face, not inflated, ovoid.
C. stricta
25. Perigynia veinless.
C. scopulorum
25. Perigynia veined.
→ 26
26. Perigynia 1–3-veined on each face.
C. 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.
C. senta
27. Perigynia narrowly ovoid or ellipsoid, 1.2–1.8 mm wide, thin-walled and leathery; scales red-brown; plants cespitose.
C. nudata
28. Perigynia veined.
→ 29
28. Perigynia veinless.
→ 30
29. Scales black; perigynia with purple-brown spots distally; apex of proximal sheaths truncate.
C. nigra
29. Scales pale red-brown; perigynia green; apex of proximal sheaths prolonged.
C. 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.
C. endlichii
31. Perigynia green, ovoid; scales red- to purple-brown.
C. torta
32. Perigynia distended by achenes, fragile, often splitting; beak obliquely bidentate.
C. 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.
C. 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.
C. scopulorum
34. Leaf blades 2–3.5 mm wide; pistillate spikes 3–4 mm thick; perigynia ellipsoid, 2–3 mm.
C. bigelowii
Source FNA vol. 23, p. 398. FNA vol. 23. Authors: Lisa A. Standley, Jacques Cayouette, Leo Bruederle.
Parent taxa Cyperaceae > Carex > sect. Phacocystis > Carex aquatilis Cyperaceae > Carex
Sibling taxa
C. aquatilis var. aquatilis, C. aquatilis var. minor, C. aquatilis var. substricta
Subordinate taxa
C. angustata, C. aperta, C. aquatilis, C. barbarae, C. bigelowii, C. crinita, C. eleusinoides, C. emoryi, C. endlichii, C. gynandra, C. haydenii, C. interrupta, C. lenticularis, C. lyngbyei, C. mitchelliana, C. nebrascensis, C. nigra, C. nudata, C. obnupta, C. paleacea, C. ramenskii, C. recta, C. rufina, C. salina, C. schottii, C. scopulorum, C. senta, C. stricta, C. subspathacea, C. torta, C. vacillans
Synonyms C. dives, C. howellii, C. panda, C. sitchensis C. section Acutae, C. section Cryptocarpae, C. section Temnemis
Name authority (Holm) Kükenthal: in H. G. A. Engler, Pflanzenr. 28[IV,20]: 311. (1909) Dumortier: Fl. Belg., 146. (1827)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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