| → 2 |
1. Culm bases purple-red. | → 10 |
2. Leaf sheaths scabrous to hispidulous; perigynium beak (0.5–)0.6–1.3 mm. | → 3 |
2. Leaf sheaths glabrous; perigynium beak 0–0.5(–0.7) mm. | → 4 |
3. Leaf blades green, glabrous abaxially or sparsely hispidulous; perigynia (4.5–)4.6– 5.6(–6.2) × 1.9–2.2(–2.3) mm; longest terminal spikes 14–34(–42) mm. | C. hitchcockiana |
3. Leaf blades, especially of overwintered leaves, glaucescent, papillose abaxially; perigynia (3.7–)4–4.7(–5.1) × 1.5–1.7(–1.8) mm; longest terminal spikes (25–)30– 46 mm. | C. brysonii |
4. Leaf blades glaucous; pistillate scales awnless or awn not more than 1(–1.9) mm. | → 5 |
4. Leaf blades deep or light green; pistillate scales usually with awns 1.2–3.7(–6) mm, rarely awnless. | → 7 |
5. Perigynia (4–)4.2–5.5(–6) mm; achene bodies 0.37–0.5 times as long as perigynia; pistillate spikes (5–)5.7–8(–9.6) mm wide; achene beak straight to bent less than 30° from vertical. | C. flaccosperma |
5. Perigynia 3.2–4.5(–4.7) mm; achene bodies 0.5–0.63(–0.67) times as long as perigynia; pistillate spikes (3.3–)4.2–6.1(–7.3) mm wide; achene beak usually bent 30–90° from vertical. | → 6 |
6. Perigynia 3.2–4(–4.1) mm, (1.5–)1.8–2.3(–2.5) times as long as wide; longest pistillate spikes with (14–)19–45(–65) perigynia, ratio of spike length (in mm) to flower number = (0.56–)0.67–1.1(–1.3). | C. glaucodea |
6. Perigynia (3.7–)3.9–4.5(–4.7) mm, (1.9–)2.1–2.6(–2.8) times as long as wide; longest pistillate spikes with 11–25(–28) perigynia, ratio of spike length (in mm) to flower number = (0.97–)1–1.3(–1.6). | C. pigra |
7. Peduncles of lateral spikes scaberulous; perigynia (6–)18–37(–86) per spike, (2.5–)2.8–3.6(–4.3) mm, 17–25-veined. | C. conoidea |
7. Peduncles of lateral spikes glabrous or scaberulous; perigynia (3–)5–16(–19) per spike, (3.6–)4–5(–5.5) mm, 40–65-veined. | → 8 |
8. Widest leaf blades 2.6–4 mm wide; ligules of proximal bracts 0.4–1.8 (–3.6) mm; perigynium apex bent; achene beaks bent. | C. impressinervia |
8. Widest leaf blades (3.7–)4.2–8.2(–9.1) mm wide; ligules of proximal bracts (1.8–)4–10.7(–12.9) mm; perigynium apex straight; achene beaks straight. | → 9 |
9. Perigynia orbicular to suborbicular in cross section, 1.8–2.3(–2.6) times as long as wide, (1.8–)2–2.6 mm wide; achenes 1.7–2.1(–2.2) mm wide, stipes (0.2–)0.3–0.4(–0.5) mm. | C. grisea |
9. Perigynia obtusely triangular in cross section, (2.2–)2.5–3.1 times as long as wide, 1.5–1.9(–2.2) mm wide; achenes (1.3–)1.5–1.7(–1.8) mm wide, stipes (0.3–)0.4–0.6 mm. | C. amphibola |
10. Plants not cespitose; rhizome internodes 2–3.4 mm thick; terminal spikes (2.8–)3.3– 4.5(–5.4) mm wide, usually much exceeding distal bract. | C. ouachitana |
10. Plants cespitose; rhizome internodes 1.2–2.2 mm thick; terminal spikes (0.9–)1.3–2.9(–3.1) mm wide, usually much exceeded by distal bract. | → 11 |
11. Perigynia spirally imbricate; proximal bracts with sheaths loose; ligules (0.9–)2–12.9 mm. | → 12 |
11. Perigynia distichously imbricate; proximal bracts with sheaths tight; ligules 4–4.9(–9.6) mm (to 2.2 mm in C. bulbostylis). | → 15 |
12. Culm bases with purple-red to (3.4–)4–7.3 cm high; widest leaf blades 2.4–4 (–5.3) mm wide; achene stipes 0.6–0.8(–0.9) mm. | C. godfreyi |
12. Culm bases with purple-red to 0.3–2.4(–7.3) cm high; widest leaf blades 3.3–8(–9.1) mm wide; achene stipes (0.2–)0.3–0.6 mm. | → 13 |
13. Perigynia (1.8–)2–2.6 mm wide, orbicular to suborbicular in cross section; achene bodies (2.6–)3.1–3.5(–3.7) mm, stipes (0.2–)0.3–0.4(–0.5) mm, bodies 4.8–9.7(–12) times as long as stipes. | C. grisea |
13. Perigynia 1.5–2.3(–2.4) mm wide, obtusely triangular in cross section; achene bodies 1.8–2.3(–2.4) mm, stipes (0.3–)0.4–0.6 mm, bodies 3.2–5.8(–7.3) times as long as stipes. | → 14 |
14. Perigynia 4.2–5(–5.2) ´ 1.5–1.9(–2.2) mm, (2.2–)2.5–3.1 times as long as wide; achene bodies broadly obovoid to oblong-obovoid, widest at 0.55–0.67(–0.7) of body length. | C. amphibola |
14. Perigynia (3.6–)3.9–4.5(–4.7) × (1.7–)1.8–2.3(–2.4) mm, 1.8–2.3(–2.5) times as long as wide; achene bodies broadly obdeltoid-obovoid, widest at (0.6–)0.65–0.8 of body length. | C. corrugata |
15. Perigynia much inflated, orbicular or suborbicular in cross section, (1.8–)2– 2.5(–2.8) mm wide, 1.6–2(–2.1) times as long as wide. | C. bulbostylis |
15. Perigynia tightly enveloping achene or slightly inflated, obtusely triangular in cross section, 1.4–2.1(–2.3) mm wide, (1.7–)2.1–3.3 times as long as wide. | → 16 |
16. Plants loosely cespitose; longer rhizomes internodes 7–58 mm. | C. paeninsulae |
16. Plants densely cespitose; longer rhizomes internodes 0.2–6(–8) mm. | → 17 |
17. Proximal bracts with bases of blades white between veins (most easily seen on abaxial surface). | C. acidicola |
17. Proximal bracts with bases of blades uniformly green. | → 18 |
18. Perigynia (1.7–)2.1–2.6 times as long as wide, apex usually abruptly contracted; beak (0.3–)0.5–1.2 mm; longest lateral spike with 2–8(–10) perigyina (including undeveloped or aborted ones). | → 19 |
18. Perigynia (2.4–)2.5–3.3 times as long as wide, apex gradually tapering; beakless or beak 0.1–0.4 mm; longest lateral spike with (5–)7–14 perigynia (including undeveloped or aborted ones). | → 21 |
19. Proximalmost spike usually considerably beyond base of culm; longest vegetative shoot 0.88–1.4 times as long as longest culm; proximal bracts with sheath front convex and elongated (0.8–)1.1–4 mm beyond apex. | C. oligocarpa |
19. Proximalmost spike usually basal; longest vegetative shoot (0.8–)1.4–4.4 times as tall as culms; proximal bracts with sheath front apices concave or truncate. | → 20 |
20. Culm bases with purple-red extending 2.7–5.2(–5.6) cm; bodies of pistillate scales (2.2–)2.5–3 mm; achene beaks (0.1–)0.2–0.3 mm. | C. calcifugens |
20. Culm bases with purple-red extending (3.7–)4.7–11.7 cm; bodies of pistillate scales 1.5–2.1(–2.5) mm; achene beaks 0.05–0.1(–0.15) mm. | C. edwardsiana |
21. Perigynia (1.9–)2–2.3 times as long as achene bodies; achene beaks (0.3–)0.4–0.7 mm. | C. planispicata |
21. Perigynia 1.7–2 times as long as achene bodies; achene beaks 0.1–0.3(–0.4) mm. | → 22 |
22. Longest (per plant) peduncle of terminal spike (2.2–)5.1–8.9(–10.4) cm; 2 distalmost lateral spikes usually widely separate or occassionally overlapping; longest vegetative shoot 0.5–1.3 times as tall as culm. | C. thornei |
22. Longest (per plant) peduncle of terminal spike 0.9–3.2(–6.8) cm; 2 distalmost lateral spikes usually overlapping; longest vegetative shoot 1.4–2.2 times as tall as longest culm. | C. paeninsulae |