Carex sect. Paludosae
in J. C. Loudon, Hort. Brit., 377. 1830.
Plants colonial, rarely cespitose, usually long-rhizomatous. Culms usually red-purple at base, sometimes only red tinged. Leaves: basal sheaths fibrous; sheath fronts membranous, sometimes becoming ladder-fibrillose, often dotted with red; sheaths and leaves somewhat septate-nodulose; blades usually M-shaped in cross section when young, sometimes channeled or involute, adaxial surface usually with 2 marginal veins more prominent than midvein; leaves 0.7–21 mm wide, glabrous or, rarely, pubescent. Inflorescences racemose, with 2–10, rarely more, spikes, dense; proximal bracts leaflike, sheathless or sheath less than 4 mm, shorter or longer than diameter of stem; proximal 1–5 lateral spikes pistillate, with 40–200 perigynia, or, sometimes, some androgynous, pedunculate, prophyllate; distal 1–6; lateral spikes staminate; terminal spike staminate. Proximal pistillate scales 1–3-veined, margins entire, apex acute to acuminate, often awned, usually glabrous, sometimes rough-ciliate apically or pubescent; distal scales acuminate or with awn less than 1/2 length of body. Perigynia usually ascending, brownish, veinless or to 28-veined at base, sometimes stipitate, not inflated, thick-walled, narrowly ovate to subcircular, rounded-trigonous to terete in cross section, 2.5–8 × 1.2–3.5 mm, 2–2.5 times as long as wide, dull, base rounded, apex tapering to beak, glabrous or pubescent; beak straight, 0.2–2 mm, emarginate to bidentate, teeth, if present, 0.1–1 mm. Stigmas 3. Achenes trigonous, smaller than bodies of perigynia; style persistent or deciduous.
Mostly temperate Asia and North America, with a few species in South America and Africa.
Species ca. 35 (14 in the flora).
Even with the members of Carex sect. Carex (as defined here) excluded, the limits of this broadly construed section are in need of a worldwide revision. Carex acutiformis differs somewhat from all the other species in having flattened-trigonous, quite thin-walled perigynia, and some authors restrict the section to that species only (T. V. Egorova 1999). Many authors also exclude the usually smaller species with hairy perigynia (e.g., K. K. Mackenzie (1931–1935, parts 2–3, pp. 326–384), as sect. Hirtae); some species, such as C. striata appear transitional and others, such as C. pellita hybridize freely with the larger, glabrous-fruited species. Carex congdonii and C. sartwelliana are also anomalous in being cespitose and having pubescent leaf blades and may also be better placed elsewhere or possibly in their own section.
|1||Perigynium body glabrous.||> 2|
|1||Perigynium body pubescent.||> 8|
|2||Widest leaves (4–)5.5–15(–21) mm wide; culms coarse, 40–135 cm; inflorescences 15–60 cm.||> 3|
|2||Widest leaves 1.5–5(–6) mm wide; culms slender, 8–90 cm; inflorescences 2.5–35(–45) cm.||> 5|
|3||Perigynia 3–4.5 mm.||Carex acutiformis|
|3||Perigynia 4.8–7.8 mm.||> 4|
|4||Longest ligules 13–40(–56) mm, much longer than wide; culms lateral, basal sheaths bladeless; perigynia usually strongly 14–28-veined.||Carex lacustris|
|4||Longest ligules 2–10(–12) mm, less than 2 times longer than wide; culms central, base with marcescent remains of previous year’s leaves; perigynia obscurely 10–15-veined.||Carex hyalinolepis|
|5||Rachis of inflorescence beyond proximal pistillate spikes with rounded, smooth angles; proximal pistillate spikes usually strongly overlapping.||Carex pumila|
|5||Rachis of inflorescence beyond proximal pistillate spikes with sharp angles, often finely scabrous; proximal pistillate spikes not or barely overlapping.||> 6|
|6||Leaves papillose abaxially, perigynia essentially veinless except for 2 lateral veins; bladeless basal sheaths brown.||Carex heterostachya|
|6||Leaves smooth abaxially, perigynia clearly veined; bladeless basal sheaths at least somewhat reddish purple.||> 7|
|7||Pistillate scales acute or shortly smooth-awned; leaves usually clearly septate-nodulose, apex of inner band of sheaths not ciliate; ligules 1.8–12.5 mm.||Carex striata|
|7||Pistillate scales scabrous-acuminate to scabrous-awned; leaves not septate-nodulose, apex of inner band of sheaths finely ciliate; ligules 0.7–1.9 mm.||Carex melanostachya|
|8||Apex of inner band of distalmost sheaths pubescent; leaves often finely pubescent, especially near sheath.||> 9|
|8||Apex of inner band of distalmost sheaths glabrous; leaves glabrous.||> 11|
|9||Beak bidentate with conspicuous, stiff teeth; staminate and pistillate scales not ciliate except at base of awn, glabrous or nearly so abaxially; plants colonial from long-creeping rhizomes, not cespitose.||Carex sheldonii|
|9||Beak irregularly bidentate or erose, ± hyaline, ciliate; staminate and pistillate scales ciliate, and usually pubescent abaxially; plants cespitose, not colonial.||> 10|
|10||Leaves finely, uniformly pubescent on both surfaces; perigynia greenish to brown, sometimes faintly purplish tinged on beak.||Carex sartwelliana|
|10||Leaves glabrous or nearly so on adaxial surface, especially distally; perigynia strongly purplish tinged.||Carex congdonii|
|11||Culms central, with marcescent remains of previous year’s leaves at base; basal sheaths of fertile culms not or usually only slightly reddened.||> 12|
|11||Culms lateral, with bladeless sheaths at base; sheaths strongly reddened.||> 13|
|12||Peduncle of staminate spike(s) (2–)3.5–15 cm, culms mostly 40–90 cm.||Carex striata|
|12||Peduncle of staminate spike(s) 0.7–3 cm; culms 10–40(–50) cm.||Carex halliana|
|13||Perigynia 4.5–6.5 mm, sparsely short-pubescent, cellular detail and venation of perigynium clear.||Carex houghtoniana|
|13||Perigynia 2.8–4.5(–5.2) mm, densely pubescent, cellular detail and venation of perigynium obscured.||> 14|
|14||Apex of perigynium beak friable, erose, not regularly bidentate; peduncle of staminate spike 0.2–2 cm.||Carex vestita|
|14||Apex of perigynium beak firm, bidentate with teeth 0.2–0.8 mm; peduncle of staminate spike (0.8–)2–9 cm.||> 15|
|15||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 long filiform tip; leaves and proximal bract with midvein forming prominent, sharply pointed keel for much of length.||Carex pellita|
|15||Leaf blades involute to triangular-channeled, 0.7–2(–2.2) mm wide, those of vegetative shoots especially long-prolonged into curled, filiform tip; leaves and proximal bract with midvein low, rounded, forming inconspicuous keel (at least proximally).||Carex lasiocarpa|