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1 Pistillate scales (excluding the awns, if present) shorter than the perigynia at least in the middle portions of the spikes, the apical portion of the pistillate scales narrower than the perigynia beaks and not completely covering them, the apex awned in some species. | |
6 Pistillate scales in middle or lower portions of spikes with apex acuminate with subulate or awned tip. | |
9 Inflorescences dense or open, spikes usually overlapping; pistillate scales acuminate; perigynia usually ascending | |
10 Perigynia (5.8-) 6.0-7.1 mm at longest; perigynium beak 2-2.8 mm long; pistillate scales with apex white-hyaline, acuminate-awned, fragile, membranaceous, and often curled, midvein not extending to tip | |
10 Perigynia (2.3-) 2.5-5.9 (-6.3) mm at longest; perigynium beak 0.85-2.2 (-2.5) mm long; pistillate scales with apex firm, greenish to reddish brown, straight, midvein extending to tip. | |
12 Perigynium body cuneately tapered to the base, the body of the perigynium more-or-less diamond-shaped; inflorescences dense, stiffly erect, with 3-5 spikes | |
12 Perigynium body convexly tapered to the base (the base rounded), the body of the perigynium ovate, elliptic, orbiculate, or weakly obovate; inflorescences dense and erect or open and nodding, with 3-11 spikes. | |
14 Beaks widely spreading, > ½ the length of the suborbicular perigynium body; lateral spikes with tapered staminate bases 2-6 mm long; [of freshwater wetlands] | |
15 Perigynia < 2 mm wide. | |
17 Lower perigynia of each spike appressed-ascending to somewhat spreading (at a 30-75 degree angle); spikes subglobose to ovate-oblong; pistillate scales evident, 2.0-3.0 mm long. | |
20 Perigynia (2.5-) 2.6-4 × as long as wide, the body lanceolate, distance from beak tip to top of achene 2.2-5 mm | |
22 Inflorescences dense or open, spikes usually overlapping; pistillate scales acuminate; perigynia usually ascending | |
23 Perigynium body ovate, elliptic, or orbiculate, widest toward the base or near the middle (excluding the beak). | |
25 Inflorescences on tallest culms compact, 1.5-3 × as long as wide, erect, the spikes overlapping, the lowest internode of the inflorescence 1-6 (-7.5) mm, ½ to 1/5 (-¼) the length of the inflorescence | |
26 Achenes 0.9-1.3 mm wide; perigynia often 3-veined on the inner face; inflorescences 12-60 mm long. | |
27 Perigynia broadly elliptic or nearly orbiculate, the wing margin 0.4-0.8 mm wide, 0-6 veined on the inner face | |
25 Inflorescences on tallest culms elongate, more-or-less open toward the base, (2.5-) 3.0-5.1 × as long as wide, often arching or nodding at the tip; spikes more-or-less separate; lowermost internode (5-) 7-19 mm long, mostly 1/5-1/3 (-1/2) the length of the inflorescence. | |
29 Sheaths smooth, often whitish-mottled; perigynium beak spreading, exceeding the pistillate scales by 0.7-1.6 mm; beak and shoulders of perigynia greenish to yellowish or greenish brown at maturity | |
15 Perigynia > 2 mm wide. | |
30 Spikes 12-28 mm long, with tapered base and acute tip; perigynium body lanceolate, 6-9 mm long; vegetative culms conspicuous | |
30 Spikes either shorter than 12 mm or longer and with either rounded bases or tips or both; perigynium body ovate, elliptic, orbicular, or obovate, or lanceolate (if lanceolate, then shorter than 6 mm long); vegetative culms conspicuous or not. | |
31 Perigynium bodies obovate, widest toward the tip; leaf sheaths green-veined adaxially nearly to the summit, or with a narrow Y-shaped hyaline area. | |
33 Perigynia (5.6-) 6.0-7.1 × 3.3-4.6 (-4.8) mm, exceeding the subtending scale by 1.5-2.6 mm; staminate and proximal pistillate scales obtuse to acute; pistillate scales 2.4-3.2 (-3.4)× as long as wide | |
33 Perigynia (4.5-) 4.8-6.0 (-6.3) × 2.5-3.8 mm, exceeding the subtending scale by (0.4-) 0.6-1.4 (-1.6) mm; staminate and proximal pistillate scales acuminate; pistillate scales (2.6-) 2.9-3.7 (-4.2)× as long as wide | |
34 Inflorescences arching or nodding, 2.3-8.4 cm long; spikes widely separated. | |
35 Sheaths smooth, summits concave, only reaching base of leaf blade; pistillate scales yellowish to reddish brown; [Interior Highlands and adjacent provinces, AR, LA, OK, and ne. TX] | |
38 Pistillate scales white-hyaline to pale silvery-brown, obtuse; achenes 0.7-1 mm wide; achene apiculum < 0.4 mm long; [widespread] | |
38 Pistillate scales reddish brown, acute; achenes 0.9-1.2 mm wide; achene apiculum 0.4-0.8 mm long; [Interior Highlands and adjacent areas] | |
31 Perigynium bodies lanceolate, ovate, elliptic, orbicular, or reniform, widest at the middle or toward the base; leaf sheaths various, some with prominent hyaline band near the apex adaxially. | |
39 Plants clumping; vegetative culms few, inconspicuous, usually with fewer than 15 leaves, not strikingly 3-ranked; achenes 1-1.6 (-1.7) × as long as wide; larger spikes with 15-80 perigynia. | |
40 Perigynia finely granular-papillose (as seen with 30× magnification), the body reniform to orbiculate, 0.6-0.9 ×as long as wide, 3.5-4.5 (-4.9) mm wide; lowermost pistillate scale obtuse-rounded | |
43 Leaf sheaths finely papillose, at least near apex; perigynia membranaceous, with brown achene clearly visible through hyaline adaxial face, usually with reddish brown tinged wings, strongly, evenly 4-8-veined adaxially over achene; pistillate scales usually reddish brown; anthers (2.4-)2.8-4.2 mm; plants in small clumps (usually fewer than 25 culms) in dry to mesic habitats | |
43 Leaf sheaths smooth; perigynia herbaceous, opaque, with achene not clearly visible through adaxial face, with greenish or pale brown wings, finely and irregularly (0-)1-7-veined over achene adaxially; pistillate scales pale yellowish brown to brown; anthers (1.8-)2.2-3.6 mm; plants often in dense, large clumps (to 200 culms) in wet habitats. | |
44 Staminate and pistillate scales acuminate-awned, tip white to brownish hyaline, membranaceous, often ± curled, midvein fading before tip; beak of larger perigynia 2.0-2.6 (-2.8) mm long; perigynium body (1.3-) 1.4-2.1× as long as the beak | |
44 Staminate and pistillate scales obtuse to acuminate, tip firm, herbaceous, flat or inrolled, midvein prominent to tip; beak (1.2-) 1.5-2.1 (-2.3) mm long; perigynium body 1.9-3× as long as the beak | |
45 Leaf sheaths green-veined adaxially nearly to the summit; inflorescences dense to somewhat open, erect, the lowermost internode usually < 8 (-12) mm long | |
45 Leaf sheaths with white-hyaline area adaxially; inflorescences open or dense. | |
47 Perigynium body narrowly to broadly ovate, greenish; pistillate scales with green midstripe, hyaline or pale margins (rarely brown tinged); leaves 2.5-6.5 mm wide, the sheaths green mottled, with mouth truncate, and prolonged to 2 mm distal to base of the leaf blades | |
47 Perigynium body broadly ovate, broadly elliptic, or orbiculate, yellowish to tan brown; pistillate scales greenish or dark brown; leaves 1.5-4 (-5) mm wide, the sheaths usually evenly colored, with mouth concave. | |
49 Perigynia strongly and evenly 4-8-veined over the achene adaxially, (4.5-) 5.1-5.5 mm long; pistillate scales usually (1.0-) 1.4-2.3 mm shorter than the perigynia; anthers (2.4-) 2.8-4.2 mm long | |
49 Perigynia veinless or faintly and irregularly 0-4 (-6)-veined over the achene adaxially, 2.5-4.2 mm long; pistillate scales 0.2-1.3 mm shorter than the perigynia; anthers 1.0-2.1 mm long | |
52 Achenes 1.2-1.8 mm long, 1.0-1.3 mm wide; perigynia 2.5-4.2 mm long, 1.5-2.3 (-2.5) mm wide, mostly 2-4 (-6)-veined adaxially | |
52 Achenes (1.6-) 1.7-2.2 mm long, (1.2-) 1.4-1.8 mm wide; perigynia 3.2-5.5 mm long, 2.5-3.6 mm wide, veinless or faintly 1-5 (-7)-veined adaxially. | |
53 Perigynia 3.2-4.8 (-5.2) mm long; beak 0.8-1.5 mm long; pistillate scales 3.3-4.0 (-4.3) mm long, acute; achenes 1.0-1.3 (1.4) × as long as wide | |
55 Perigynia veinless or faintly and irregularly 1-5-veined over the achene adaxially, more-or-less orbicular, the bodies (2-) 2.3-3.2 mm long, (0.7-) 0.9-1.1 (-1.3) × as long as wide; pistillate scales mostly acute, about as long as to 0.7 (-0.9) mm shorter than the subtended perigynium (flattened and measured separately) | |
55 Perigynia strongly 4-6-veined over the achene adaxially, broadly ovate to broadly elliptic, (or rarely nearly orbicular), the bodies (2.7-) 3-4 mm long, (0.9-) 1.0-1.6 × as long as wide; pistillate scales mostly obtuse, 0.7-1.7 mm shorter than the subtended perigynium (flattened and measured separately) |