1 Apex of
perigynium beak terminated by 2 teeth, mostly > 0.5 mm long.
2 Perigynia > 4× as long as wide (8-15 × 1-3 mm).
3 Apical teeth of
perigynium beak reflexed ;
achene elongate;
pistillate scale with 1-veined center
2 Perigynia < 4× as long as wide.
4 Perigynia > (9-) 10 mm long.
5 Sheath , at least the
proximal sheath fronts, densely
tomentose at mouth;
apical teeth of
perigynium beak often > 1 mm long
5 Sheath glabrous ;
apical teeth of
perigynium beak not more than 1 mm.
6 Perigynia 7-11-, 5-12-, or 12-25-veined
6 Perigynia 12-34-veined.
7 Basal and
proximal leaf
sheath reddish or purplish
7 Basal and
proximal leaf
sheath yellowish to brown, without trace of red or purple
4 Perigynia < 10 mm long.
8 At least
proximal pistillate scale with long, rough
awn .
9 Perigynia with 2 strong
marginal veins, otherwise veinless or veined only proximally; leaves not
septate -
nodulose .
9 Perigynia with 5+ strong veins extending length of bodies; leaves
septate -
nodulose .
10 Perigynium beak with
apical teeth (0.4-) 0.6-3 mm long, often > 1 mm long
10 Perigynium beak with
apical teeth < 1 mm long.
11 Perigynium body
obovoid , widest distally;
proximal bract > 3× as long as the
inflorescence
11 Perigynium body
ovoid or
lanceoloid or
ellipsoid , widest at middle or proximally;
proximal bract usually < 2× as long as the
inflorescence .
12 Perigynium beak 0.9-1.7 mm long; mature
perigynia dull
12 Perigynium beak 0.2-6 mm long; mature
perigynia somewhat
glossy
13 Culm with some red or purple at
base .
14 At least
proximal perigynia in each
spike spreading or
reflexed ; leaves sparsely
septate -
nodulose
13 Culm brown or black at
base , without trace of red or purple.
15 Pistillate scale with 5-7-veined center
15 Pistillate scale with 1-3-veined center.
16 Leaves not
septate -
nodulose
16 Leaves at least sparingly
septate -
nodulose
1 Apex of
perigynium beak entire ,
emarginate , or with teeth mostly < 0.5 mm long.
17 Leaf
blade variously hairy.
18 Plant brown or black at
base
18 Plant with at least some red or purple at
base
20 Leaves much wider, often over 10 mm wide
19 Bract , at least the
proximal , with distinct
blade .
21 Young leaves V-shaped or rounded in cross section,
adaxial surface without 2
marginal veins more prominent than
midvein or other veins.
22 Perigynium beak with 2 distinct terminal teeth, usually > 0.2 mm long.
23 At least
proximal pistillate scale awned,
awn at least 1/2 as long as body; leaves conspicuously
septate -
nodulose .
24 Base of
culm strongly red or purple; leaves 2-4 mm wide
24 Base of
culm brown, without or with only trace of red or purple; leaves 4-15 mm wide.
25 Distal pistillate scale acute ,
acuminate , or short-awned,
awn less than 1/2 length of body
25 Distal pistillate scale with
awn at least about as long as body
23 Pistillate scale obtuse to
acuminate , sometimes very shortly awned; leaves not or only weakly
septate -
nodulose .
26 Plants with long-creeping
rhizome ; leaves usually not
septate -
nodulose
26 Plants with short-
ascending rhizome ; leaves at least sparingly
septate -
nodulose .
22 Perigynium beak entire ,
emarginate , or with 2
apical teeth < 0.2 mm long.
28 Perigynia rounded at
base , sides proximally distinctly
convex .
29 Perigynia with veins slightly prominent
29 Perigynia with veins slightly
impressed
28 Perigynia tapering at
base , sides straight or only slightly
convex proximally.
30 Perigynia rounded at
apex , beakless or with
beak < 0.3 mm long.
31 Widest leaf
blade < 5 mm wide; plants usually not
cespitose
31 Widest leaf
blade usually > 5 mm wide; plants usually
cespitose
30 Perigynia tapering to
beak at least > (0.3-) 0.5 mm long.
32 Proximal perigynia in each
spike spreading at right angles or
reflexed at maturity; leaves and
sheath sparsely
septate -
nodulose
33 Plants usually
colonial ;
perigynia and leaves often
papillose
33 Plants
cespitose ;
perigynia and leaves not
papillose
21 Leaf
blade M-shaped in cross section when young,
adaxial surface with 2
marginal veins more prominent than
midvein and other
marginal veins, sometimes apparent only on
proximal leaves and on
proximal part of
blade .
34 Perigynium beakless or with
beak < 0.5 mm long,
entire or with 2
apical teeth < 0.1 mm long.
35 Widest leaf
blade (usually
basal ) > 10 mm wide.
37 Perigynia trigonous with rounded angles in cross section
37 Perigynia sharply
trigonous in cross section
35 Widest leaf
blade < 10 mm wide.
38 Perigynia not prominently veined, veins somewhat
impressed
38 Perigynia at least slightly prominently veined or veinless except for 2
marginal veins.
39 Perigynia rounded at
base , sides proximally
convex
39 Perigynia tapering at
base , sides proximally straight,
concave or slightly
convex .
41 Perigynia sharply
trigonous in cross section
41 Perigynia terete or with rounded angles in cross section.
42 Perigynia with 2
marginal veins and not more than 10 veins on faces
42 Perigynia with more than 12 veins.
43 Plants usually
colonial , not
cespitose ;
perigynia papillose at least faintly.
34 Perigynium with distinct
beak > 0.5 mm, usually with
apical teeth > 0.1 mm long.
44 Perigynia with 2 distinct
marginal veins, otherwise veinless or with very weak veins proximally.
45 Perigynium beak entire ,
emarginate , or with
apical teeth < 0.1 mm long
45 Perigynium beak with
apical teeth 0.2-1 mm.
46 Perigynium beak usually < 1 mm long.
46 Perigynium beak sometimes > 2 mm long
44 Perigynia with more than 2 veins extending most of length of bodies.
47 Pistillate scale with narrow, indistinct bodies, scarcely enlarged at
base
47 Pistillate scale with wide, flat bodies, sometimes terminating in
awn .
49 Perigynium with not more than 5 veins extending length of body on
abaxial face, veinless or weakly veined on
adaxial face
49 Perigynium with > 8 equally prominent veins on both faces.
50 Perigynia bluntly angled in cross section
50 Perigynia sharply angled in cross section
48 Perigynium beak with 2 distinct teeth at
apex , usually > 0.2 mm long.
51 Pistillate spike , at least the
proximal ,
lax ,
proximal and middle
perigynia separated by
internode at least 1/4 their length; leaves and
sheath not
septate -
nodulose
51 Pistillate spike dense,
proximal and middle
perigynia separated by
internode less than 1/10 their length;
proximal leaves and
sheath sparingly
septate -
nodulose .
52 Pistillate scale , at least
proximal , awned,
awn at least 1/4 of
scale body length.
53 Distal pistillate scale acuminate or with
awn less than 1/2 body length;
staminate spike usually 2+
53 Distal pistillate scale awned,
awn usually more than 1/2 body length;
staminate spike 1, sometimes with 1 much smaller
spike laterally
52 Pistillate scale obtuse to
acute or
apiculate ,
apiculus not more than 1/10 of body length.
54 Culm brown at
base , without trace of red or purple;
achene with
style deciduous