Carex sect. Deweyanae
in N. L. Britton et al., N. Amer. Fl. 18: 114. 1931.
Plants densely to loosely cespitose, short to long rhizomatous. Culms brown at base. Leaves: basal sheaths fibrous; sheath fronts membranous; blades flat or V-shaped in cross section when young, glabrous. Inflorescences racemose with (2–)3–9 spikes; proximal bracts filiform or leaflike, sheathless; lateral spikes gynecandrous or pistillate, rarely staminate or androgynous, sessile, without prophylls; terminal spike usually gynecandrous. Proximal pistillate scales whitish to castaneous, hyaline margins and green, 1-veined center, apex acute or short-awned. Perigynia appressed-erect to spreading, occasionally recurved, veined or veinless on both faces, sessile, ovate to narrowly lanceolate, plano-convex, base cuneate to rounded, with spongy tissue, margins acutely angled, serrulate or entire distally, apex tapering or abruptly beaked, glabrous; beak 0.4–2.5(–2.8) mm, with abaxial suture usually nearly closed, margins entire or serrulate, apex entire to shortly bidentate. Stigmas 2. Achenes brown, sessile, biconvex or plano-convex, almost as large as bodies of perigynia, apex rounded; style deciduous, enlarged at base.
North America, e Asia.
Species 8 (6 in the flora).
Species of Carex sect. Deweyanae, particularly C. bolanderi, C. deweyana, and C. leptopoda, can be difficult to identify because of their great morphologic variability and overlapping ranges of measurements of diagnostic characters. For correct identifications, specimens must bear mature perigynia, be complete, and be ample. Perigynia from the middle portions of spikes should be examined because they are the most representative. Perigynium beak length reported here is the distance from the achene summit (as viewed through the perigynium) to the perigynium apex. Culm widths are taken from the middle of the culm.
|1||Longest (per plant) proximal spike 5.5–9.8 mm; perigynium beak 0.4–1.1(–1.3) mm; widest leaf blade 1.3–2(–2.3) mm wide.||Carex laeviculmis|
|1||Longest (per plant) proximal spike 8.7–27 mm; perigynium beak 0.9–2.8 mm; widest leaf blade 1.3–5.9 mm wide.||> 2|
|2||Perigynia (3.3–)4.1–6.7 times as long as wide, (3–)4–8-veined abaxially, veins extending unbroken from perigyium base to base of perigynium beak, achenes 1.9–2.9 times as long as wide; widest leaf blade 1.3–4.4 mm wide.||Carex bromoides|
|2||Perigynia 2.3–3.9(–4.2) times as long as wide, 0–7-veined abaxially, veins extending unbroken from perigyium base to base of perigynium beak, achenes 1.2–1.8 times as long as wide; widest leaf blade (2.2–)2.4–5.9 mm wide.||> 3|
|3||Ligule of distal leaf on culm 0.9–2.2 mm; pistillate scale body 2.8–4.2 mm; achenes (1.8–)1.9–2.2 mm; longest infructescence with 2–5 spikes.||Carex deweyana|
|3||Ligule of distal leaf on culm (2.1–)3.1–9.1 mm; pistillate scale body 2.1–3.3(–3.8) mm; achenes 1.4–1.9(–2.2) mm; longest infructescence with (4–)5–9 spikes.||> 4|
|4||Perigyinium beak 0.9–1.5(–1.7) mm, 28–38% of perigynium length; pistillate scale body (2.3–)2.7–3.8 mm.||Carex leptopoda|
|4||Perigyinium beak (1.4–)1.6(–2.7) mm, 38–50% of perigynium length; pistillate scale body 2.1–2.9(–3.1) mm.||> 5|
|5||Perigynium apex with teeth 0–0.2(–0.4) mm, 0–8% perigynium length (avoid perigynia with teeth lengthened by tearing of sinus between teeth); culm papillose at mid height (20X on young culms).||Carex infirminervia|
|5||Perigynium apex with teeth (0.2–)0.3–1 mm, (6–)9–20% perigynium length (avoid perigynia with teeth lengthened by tearing of sinus between teeth); culm smooth, serrulate, or scabridulous at mid height (20X).||Carex bolanderi|