What’s a dichotomous key?
Help
Section Cyperoideae
See list of 29 species in this sectionCarex section Cyperoideae (which includes sedges formerly placed in section Ovales) comprises a very difficult section of sedges given the narrow morphological gaps between some taxa. Flowering individuals from later in the season often have short, contracted inflorescences, regardless of their early season form. Such individuals are not accounted for in the key. Mature perigynia are a requisite for keying, given the importance of perigynium and achene dimensions. Perigynia from about ⅓ the spike length (measuring from the base) are best used for the following key. Reference: Mastrogiuseppe et al. (2002).
-
1a. Longest bract of inflorescence 5–20 cm long, (3–) 5 or more times as long as the inflorescence; distance from apex of achene to apex of perigynium 3–5 mm [Fig. 86]
-
1b. Longest bract of inflorescence rarely exceeding 5 cm, up to 2 times as long as inflorescence; distance from apex of achene to apex of perigynium 1.2–3.1 (–3.7) mm [Figs. 79,83,84]
-
2a. Carpellate scales nearly equaling to slightly exceeding the length of the perigynia, mostly concealing the beaks of the perigynia in intact spikes [Fig. 78]
-
3a. Leaves stiff, very glaucous (except in shade), many with rounded auricles at the summit of the sheath; floral scales white or white-brown; plants of Atlantic coast shores and near shore habitats (in part)
-
3b. Leaves softer, slightly or not at all glaucous, without auricles; floral scales white-green or brown; plants usually not coastal
-
4a. Carpellate scales about as wide as the perigynia they subtend; achenes 1.6–2 mm wide; lowest bract usually broad and flat at base, sometimes exceeding the spike it subtends
-
4b. Carpellate scales narrower than the perigynia they subtend; achenes 0.7–1.6 mm wide; lowest bract usually setaceous and shorter than the spike it subtends
-
5a. Beak of perigynium flat, winged, and minutely serrulate to the apex [Fig. 83]
-
6a. Perigynium body lanceolate, 0.9–1.4 mm wide, with the marginal wing usually conspicuously reduced (or even absent) on the lower half of the body [Fig. 83]
-
6b. Perigynium body ovate, (1.5–) 1.7–2.5 mm wide, with the marginal wing scarcely and gradually (if at all) reduced on the lower half of the body [Fig. 84]
-
7a. Perigynia smooth, adaxially without veins or with 4–8 curving veins of unequal length; inflorescence with 3–7 (–11) spikes, the upper ones usually separate; carpellate scales red-brown to green or gold-brown
-
7b. Perigynia granular-papillose, adaxially with (4–) 5–8 (–10) ± parallel veins of equal length; inflorescence with (3–) 7–15 spikes, the upper ones usually densely aggregated; carpellate scales pale white-green
-
-
-
5b. Beak of perigynium cylindric, unwinged, and entire in the apical (0.3–) 0.4–1 mm [Fig. 84]
-
8a. Perigynia 3.4–4.7 (–5.2) mm long; inflorescence usually erect, with approximate spikes, the internode between the second and third spike counting from the base (2.5–) 3–6 mm long; apical, herbaceous portion of leaf sheath smooth
-
8b. Perigynia (3.7–) 4.5–6 mm long; inflorescence usually open and ± nodding, the internode between the second and third spike (2.5–) 4–10 mm long; apical, herbaceous portion of leaf sheath minutely papillose
-
-
-
-
-
2b. Carpellate scales, excluding the awns (when present), clearly exceeded by the perigynia, the tip of the perigynia beaks visible in intact spikes [Fig. 85]
-
9a. Perigynia up to 2 mm wide
-
10a. Carpellate scales of the basal median portion of the spike tapering to a slender, acuminate point, often prolonged into a short awn tip
-
11a. Perigynia bodies lanceolate, 0.9–1.3 mm wide; achene 0.6–0.8 mm wide; inflorescence congested, the lowest internode 2–3 (–5) mm long
-
11b. Perigynia bodies lanceolate to ovate, obovate, or nearly orbicular, 1.2–2.9 mm wide; achene 0.7–1.1 mm wide; inflorescence congested to open, the lowest internode 2–18 mm long
-
12a. Perigynia 1.2–2.1 mm wide, 2.6 or more times as long as wide; leaf sheaths opposite the blade with a prolonged, narrow hyaline area
-
12b. Perigynia 1.8–2.8 mm wide, up to 2.5 times as long as wide; leaf sheaths opposite the blade firm and green-veined nearly to the summit, the hyaline area very short
-
13a. Staminate portion of lateral spikes 2–6 mm long; beak of perigynium spreading, usually 50% or more of the length of the nearly orbicular body; plants of freshwater wetlands
-
13b. Staminate portion of lateral spikes shorter than 2 mm; beak of perigynium ascending, less than 50% of the length of the narrow-ovate to obovate body; plants of saline-influenced habitats
-
-
-
-
10b. Carpellate scales of the basal median portion of the spike obtuse to subacuminate at the apex, without awn tips
-
14a. Marginal wing of perigynium usually conspicuously reduced (or even absent) in the lower half of the body; leaves with blades 3–7.5 mm wide, with narrow, decurrent wings on the sheath that are continuous with the blade midrib and margins; vegetative shoots conspicuous, with numerous leaves spaced throughout the apical half of the stem
-
15a. Perigynia in basal portion of spike spreading or recurved; spikes spherical or subspherical; carpellate scales 1.6–2.3 mm long
-
15b. Perigynia in basal portion of spike appressed-ascending to ascending-spreading; spikes subspherical to ovoid or obovoid; carpellate scales 2–3 mm long
-
16a. Inflorescence erect, with congested and overlapping spikes, each spike with (30–) 40 or more perigynia; perigynia appressed-ascending to ascending; apical portion of the leaf sheath opposite the blade firm and green-veined nearly to the summit, the hyaline area 3–8 mm long
-
16b. Inflorescence arching or nodding, with separate spikes in the basal portion (uncommonly the inflorescence ± congested), each spike with 15–30 perigynia; perigynia ascending to spreading; apical portion of the leaf sheath opposite the blade with a prolonged, hyaline area 4–20 mm long
-
-
-
14b. Marginal wing of perigynium scarcely and gradually (if at all) reduced in the lower half of the body; leaves with blades 1–4.5 mm wide (up to 6.5 mm in C. normalis), with inconspicuous, rounded edges on the sheath that are continuous with the blade midrib and margins; vegetative shoots inconspicuous, with few leaves clustered near apex of stem
-
17a. Body of the perigynium elliptic to orbicular or obovate, broadest at or above the middle [Fig. 79]
-
18a. At least some spikes with a pronounced, narrow, staminate base longer than 2 mm; inflorescence arching to nodding; achenes ovate in outline (in part)
-
18b. Spikes with an inconspicuous staminate base shorter than 2 mm; inflorescence ± erect; achenes narrow-oblong to oblong or elliptic in outline
-
19a. Perigynium body elliptic to suborbicular, broadest near the middle; achenes 0.9–1.3 mm wide; inflorescence congested, the lowest internode 1.5–6 mm long (in part)
-
19b. Perigynium body obovate [Fig. 79]; achenes 0.7–1 mm wide; inflorescence close, but usually not congested near the base, the lowest internode (1–) 3–14 mm
-
20a. Carpellate scales obtuse; perigynium beak triangular [Fig. 81], appressed-ascending; styles straight; apical, herbaceous portion of leaf sheath minutely papillose
-
20b. Carpellate scales acute; perigynium beak slender, spreading [Fig. 79]; styles laterally sinuous; apical, herbaceous portion of leaf sheath smooth
-
-
-
-
17b. Body of the perigynium broad-lanceolate to ovate, widest below the middle
-
21a. Inflorescence congested, with crowded spikes, the lowest internode usually shorter than 6 mm
-
22a. Perigynia adaxially with 1–3 faint veins near the base; achenes 0.6–0.9 mm wide
-
22b. Perigynia adaxially usually with 3–7 conspicuous veins; achenes 0.9–1.2 mm wide
-
23a. Leaves with blades 1.5–3.5 mm wide, with lower sheaths that are tight, ± evenly colored, and sometimes cross-corrugated; apical, herbaceous portion of leaf sheath minutely papillose; mature perigynia tan to brown (in part)
-
23b. Leaves with blades 2.2–6 (–6.5) mm wide, with lower sheaths that are loose, green and white-mottled or -striped, and not corrugated; apical, herbaceous portion of leaf sheath smooth; perigynia green (at least apically) (in part)
-
-
-
21b. Inflorescence elongate, the lower spikes remote, the lowest internode usually longer than 6 mm
-
24a. Leaves with blades 2.2–6 (–6.5) mm wide, the lower sheaths loose; flowering stems with 3–7 leaves; apical, herbaceous portion of the leaf sheath smooth (in part)
-
24b. Leaves with blades 1.3–2.5 (–3) mm wide, the lower sheaths tight; flowering stems with 2–4 leaves; apical, herbaceous portion of at least some leaf sheaths minutely papillose (smooth in the very rare C. echinodes)
-
25a. At least some leaf sheaths minutely papillose near the apex on the herbaceous portion, not prominently mottled or striped with white near the base; beaks of perigynia of intact spikes appressed to spreading-ascending, exceeding the subtending scales by 0–0.8 mm; beaks and shoulders of perigynia stramineous to red-brown at maturity; carpellate scales mostly 0.8–1 times as long as the perigynia they subtend
-
25b. Leaf sheaths smooth near the apex, often mottled or striped with white near the base; beaks of perigynia of intact spikes spreading, exceeding the subtending scales by 0.7–1.6 mm; beaks and shoulders of perigynia green to green-brown at maturity; carpellate scales mostly 0.6–0.85 times as long as the perigynia they subtend
-
-
-
-
-
-
-
9b. Perigynia wider than 2 mm
-
26a. Leaves stiff, very glaucous (except in shade), many with rounded auricles at the summit of the sheath; floral scales white or white-brown; plants of Atlantic coast shores and near shore habitats (in part)
-
26b. Leaves softer, not or only slightly glaucous, without auricles; scales light green to green or white-brown to brown; plants not of coastal shores (except C. hormathodes)
-
27a. Carpellate scales of the basal median portion of the spike tapering to a slender, acuminate point, often prolonged into a short awn tip
-
28a. Perigynia 2.5–3.8 mm wide, broad-obovate; leaf blades 2.5–6 mm wide
-
28b. Perigynia 1.9–2.8 mm wide, narrow-ovate to orbicular or obovate; leaf blades 1–3 mm wide
-
-
27b. Carpellate scales of the basal median portion of the spike obtuse to subacuminate at the apex, without awn tips
-
29a. Perigynia obovate, widest above the middle; apical portion of the leaf sheath opposite the blade firm and green-veined nearly to the summit
-
30a. Leaves with blades 3–6 (–8) mm wide, the summit of the sheaths truncate (unless torn); perigynia adaxially with inconspicuous veins
-
30b. Leaves with blades 2–4.5 mm wide, the summit of the sheaths concave; perigynia adaxially with 4–many veins
-
-
29b. Perigynia broad-lanceolate, ovate, elliptic, or orbicular, widest at or below the middle; apical portion of the leaf sheath opposite the blade with a prolonged, hyaline area (except in C. molesta and C. normalis)
-
31a. Perigynia broad-lanceolate to ovate, green (at least apically); leaves with blades 2.2–6 (–6.5) mm wide, the lower sheaths green and white-mottled or -striped; sheath summits truncate, prolonged up to 2 mm above sheath apex (in part)
-
31b. Perigynia ovate to broad-ovate or elliptic to orbicular, yellow-brown to tan or brown; leaves with blades 1.5–4 (–5) mm wide, the lower sheaths ± evenly colored; sheath summits usually concave (sometimes truncate and prolonged)
-
32a. Perigynia bodies broad-elliptic to orbicular, broadest near the middle
-
33a. At least some spikes with a pronounced, narrow, staminate base longer than 2 mm; inflorescence arching to nodding, the lowest internode 3–18 mm long; achenes ovate in outline (in part)
-
33b. Spikes with an inconspicuous staminate base shorter than 2 mm; inflorescence ± erect, the lowest internode 1.5–6 mm; achenes narrow-oblong to elliptic in outline (in part)
-
-
32b. Perigynia bodies ovate to broad-ovate
-
34a. Perigynia (1.4–) 1.6–2.4 mm wide; achenes 0.9–1.2 mm wide; hyaline region of leaf sheath opposite leaf blade sometimes cross-corrugated (in part)
-
34b. Perigynia (2–) 2.3–4.2 mm wide; achenes 1.1–1.8 mm wide; hyaline region of leaf sheath not corrugated
-
35a. Marginal wing of perigynium evenly and minutely serrulate [Fig. 80]; apical, herbaceous portion of leaf sheaths smooth
-
35b. Marginal wing of perigynium often irregularly erose or toothed, in addition to minutely serrulate [Fig. 82]; apical, herbaceous portion of leaf sheaths minutely papillose
-
36a. Perigynia 3.3–5 mm long, adaxially veinless or with 1–5 faint veins [Fig. 82], exceeding the carpellate scales by 0.2–1.3 mm; anthers 1.3–2.6 mm long
-
36b. Perigynia (4.5–) 5.1–6.7 (–7.1) mm long, adaxially with 4–8 veins, exceeding the carpellate scales by (1–) 1.4–2.3 mm; anthers (2.4–) 2.8–4.2 mm long
-
-
-
-
-
-
-
-
-
-
Show photos of:
Each photo represents one species in this section.