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).
2 Perigynia < 4× as long as wide.
4 Perigynia > (9-) 10 mm long.
5 Sheaths , at least the
proximal sheath fronts, densely
tomentose at mouth;
apical teeth of
perigynium beak often > 1 mm long
5 Sheaths 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
sheaths reddish or purplish
7 Basal and
proximal leaf
sheaths yellowish to brown, without trace of red or purple
4 Perigynia < 10 mm long.
8 At least
proximal pistillate scales 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 Culms with some red or purple at
base .
14 At least
proximal perigynia in each
spike spreading or
reflexed ; leaves sparsely
septate -
nodulose
13 Culms brown or black at
base , without trace of red or purple.
15 Pistillate scales with 5-7-veined center
15 Pistillate scales 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
blades variously hairy.
18 Plant brown or black at
base
18 Plant with at least some red or purple at
base
19 Bracts without
blades .
20 Leaves much wider, often over 10 mm wide
19 Bracts , 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 scales 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 scales acute ,
acuminate , or short-awned,
awn less than 1/2 length of body
25 Distal pistillate scales with
awn at least about as long as body
23 Pistillate scales obtuse to
acuminate , sometimes very shortly awned; leaves not or only weakly
septate -
nodulose .
26 Plants with long-creeping
rhizomes ; leaves usually not
septate -
nodulose
26 Plants with short-
ascending rhizomes ; 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
blades < 5 mm wide; plants usually not
cespitose
31 Widest leaf
blades 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
sheaths sparsely
septate -
nodulose
33 Plants usually
colonial ;
perigynia and leaves often
papillose
33 Plants
cespitose ;
perigynia and leaves not
papillose
21 Leaf
blades 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
blades (usually
basal ) > 10 mm wide.
37 Perigynia trigonous with rounded angles in cross section
37 Perigynia sharply
trigonous in cross section
35 Widest leaf
blades < 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 scales with narrow, indistinct bodies, scarcely enlarged at
bases
47 Pistillate scales with wide, flat bodies, sometimes terminating in
awns .
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 spikes , at least the
proximal ,
lax ,
proximal and middle
perigynia separated by
internodes at least 1/4 their length; leaves and
sheaths not
septate -
nodulose
51 Pistillate spikes dense,
proximal and middle
perigynia separated by
internodes less than 1/10 their length;
proximal leaves and
sheaths sparingly
septate -
nodulose .
52 Pistillate scales , at least
proximal , awned,
awn at least 1/4 of
scale body length.
53 Distal pistillate scales acuminate or with
awn less than 1/2 body length;
staminate spikes usually 2+
53 Distal pistillate scales awned,
awn usually more than 1/2 body length;
staminate spikes 1, sometimes with 1 much smaller
spike laterally
52 Pistillate scales obtuse to
acute or
apiculate ,
apiculus not more than 1/10 of body length.
54 Culms brown at
base , without trace of red or purple;
achenes with
style deciduous