Carex sect. Stellulatae
Enum. Pl. 2: 399. 1837.
Plants cespitose, short-rhizomatous. Culms brown at base, exceeding leaves. Leaves: basal sheaths not fibrous; sheath fronts membranous, sheaths of proximal cauline leaves smooth or very weakly transversely rugose, sheaths of distal leaves with at least narrow hyaline or white-hyaline band; blades V-shaped in cross section when young, widest 0.8–5 mm wide, glabrous. Inflorescences racemose, with (1–)2–10 spikes; bracts sheathless, with inconspicuous blades, at least (1.5–)2 times as long as wide; lateral spikes gynecandrous, pistillate, or staminate, sessile, without prophylls; terminal spike gynecandrous, pistillate, or staminate. Proximal pistillate scales with apex obtuse to acute or cuspidate. Perigynia spreading, at least the proximal, veined on abaxial face, veined or veinless on adaxial face, stipitate, broadly ovate to lanceolate, usually plano-convex (to slightly biconvex in C. exilis and C. interior), base rounded to cordate, with spongy tissue, margins acutely angled, apex ± abruptly beaked, glabrous; beak 0.25–1.6 mm, with abaxial suture, margins often serrulate, apex shortly bidentate. Stigmas 2. Achenes biconvex, much smaller than bodies of perigynia; styles deciduous.
North America, Mexico, Central America, n South America, Eurasia, Australia, New Zealand, Hawaii.
Species ca. 15 (8 in the flora).
Carex sect. Stellulatae is a difficult section in which differences among species can be subtle and identification may require careful observation of perigynium shape and size. Perigynia in the section rapidly narrow towards the apex of the spikes, obscuring the shape differences among species. The perigynium or two just above the staminate portion of the spikes are sometimes misshapen. Therefore, for identification purposes, it is best to examine the third or fourth perigynium above the staminate part of the spikes.
|1||Spikes usually 1; leaves involute; anthers (2–)2.2–3.6 mm.||Carex exilis|
|1||Spikes 2–8; leaves flat or plicate; anthers 0.6–2.2(–2.35) mm.||> 2|
|2||Perigynium beak smooth-margined.||Carex seorsa|
|2||Perigynium beak at least sparsely serrulate-margined.||> 3|
|3||Widest leaves 2.8–5 mm wide.||> 4|
|3||Widest leaves 0.8–2.7 mm wide.||> 7|
|4||Proximal perigynia of spikes mostly 1.1–1.7 times as long as wide, mostly 2.1– 3 mm wide.||Carex atlantica|
|4||Proximal perigynia of spikes (1.5–)1.7–3 times as long as wide, mostly 1.2–2 mm wide.||> 5|
|5||Longer pistillate scales 2.1–3.1 mm.||Carex echinata|
|5||Longer pistillate scales 1.1–2.2 mm.||> 6|
|6||Inflorescences mostly 1.5–3 cm, the proximal 2 spikes separated by 1.3–9.5 mm.||Carex wiegandii|
|6||Inflorescences mostly 3–8.5 cm, the proximal 2 spikes separated by 10–40 mm.||Carex ruthii|
|7||Terminal spikes entirely staminate; anthers (1–)1.2–2.2(–2.35) mm.||Carex sterilis|
|7||Terminal spikes partly or wholly pistillate; anthers 0.6–2.2(–2.35) mm.||> 8|
|8||Terminal spikes without distinct clavate base of staminate scales, staminate portion, if present, less than 1 mm; anthers (1–)1.2–2.2(–2.35) mm.||Carex sterilis|
|8||Terminal spikes with distinct clavate base of staminate scales 1–8(–16.5) mm; anthers 0.6–1.6(–2) mm.||> 9|
|9||Proximal perigynia 2–3 mm wide.||Carex atlantica|
|9||Proximal perigynia 0.9–1.95 mm wide.||> 10|
|10||Proximal perigynia mostly 2.9–4.75 mm, (1.7–)1.8–3.6 times as long as wide; beak mostly 0.95–2 mm, mostly 0.45–0.85 length of body.||Carex echinata|
|10||Proximal perigynia mostly 1.9–3 mm, 1–2(–2.2) times as long as wide; beak mostly 0.4–0.95 mm, mostly 0.2–0.5 length of body.||> 11|
|11||Perigynia mostly veinless over achene on adaxial surface; perigynium beak conspicuously setulose-serrulate; perigynia often ± convexly tapered from widest point to beak, forming a “shoulder”.||Carex interior|
|11||Perigynia 1–10-veined over achene on adaxial surface; perigynium beak more sparsely serrulate with definite spaces between the often single teeth; perigynia mostly ± cuneate or even concavely tapered from widest point to beak.||Carex atlantica|