Carex sect. Spirostachyae
in J. M. Coulter, Man. Bot. Rocky Mt., 381. 1885.
Plants cespitose, short-rhizomatous. Culms red-brown at base. Leaves: basal sheaths not fibrous; sheath fronts membranous; blades not or sparingly septate-nodulose, V-shaped in cross section when young, glabrous. Inflorescences racemose, with 3–6 spikes; proximal nonbasal bracts leaflike, long-sheathing, sheath 4+ mm, longer than diameter of stem; lateral spikes pistillate, pedunculate, peduncle usually not longer than spike, prophyllate; terminal spike staminate. Proximal pistillate scales with apex acute or cuspidate. Perigynia ascending or spreading, yellow-or gray-green or brown, usually speckled reddish brown, strongly 10–16-veined, elliptic or ovate, rounded-trigonous in cross section, base cuneate, apex tapering to beak, glabrous; beak 0.4–1.4 mm, bidentate, teeth 0.2–0.4 mm. Stigmas 3. Achenes trigonous, smaller than bodies of perigynia; style deciduous.
Species ca. 15 (3 in the flora).
Carex sect. Spirostachyae is closely related to sect. Ceratocystis Dumortier and has often been included with it under the name “Extensae.” W. J. Crins and P. W. Ball (1988) clarified the distinctions between the two sections.
|1||Leaves of flowering stems channelled or involute, widest blades 1–3.5(–4.3) mm wide; distal 2–3 pistillate spikes usually clustered near stem apex beside staminate spike; staminate spikes on peduncles 0.2–1 cm; proximal bract 2–10 times as long as inflorescence.||Carex extensa|
|1||Leaves of flowering stems flat, widest blades 3.3–5 mm wide; pistillate spikes widely spaced, with at most 1 or 2 near, but not clustered about, staminate spike; staminate spikes on peduncles 1–5(–8.5) cm; proximal bract shorter than to no more than 1.5 times as long as inflorescence.||> 2|
|2||Perigynia 3.5–4.6 mm, apex contracted; beak (0.8–)1–1.4 mm, scabrous; proximal bract usually shorter than the inflorescence; longer peduncles of staminate spikes 2–5(–8.5) cm; staminate and pistillate spikes well separated; leaves gray-green.||Carex distans|
|2||Perigynia 2.6–3.5 mm, apex gradually tapered; beak 0.4–0.7 mm, smooth; proximal bract mostly equaling or exceeding inflorescence; longer peduncles of staminate spikes 1–2(–4) cm; distal 1–2 pistillate spikes usually aggregated near staminate spike; leaves yellowish green.||Carex diluta|