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Key to Carex, [26d] Section 4.0 Phaestoglochin: section Phaestoglochin (Bracteosae)

Cyperaceae

Carex

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1
Sheaths loose, membranaceous, and fragile on the ventral side, septate-nodulose and usually mottled or striped with green and white on the dorsal side; widest leaves 3-10 mm.

© Nathan Aaron
  2
Bodies of pistillate scales 1.5-2.5 mm long, 1.1-1.8 mm wide, mostly < ½ as long as the perigynia, apex obtuse to acuminate to shortly awned.
    3
Basal internodes of the inflorescence usually < 1 cm long, and usually < 2× as long as the spikes; bodies of perigynia with wing < 0.1 mm wide
 ⇒ Carex cephaloidea
    3
Basal internodes of the inflorescence usually >2 cm long, at least 2× as long as the spikes; bodies of perigynia with wing 0.1-0.2 mm wide
 ⇒ Carex sparganioides
  2
Bodies of pistillate scales 2.2-4.4 mm long, 1.2-2.4 mm wide, mostly > ½ as long as the perigynia, apex acuminate to awned.
    4
Fronts of leaf sheaths yellow or brownish, thick, firm, the back often white-spotted
 ⇒ Carex aggregata
    4
Fronts of leaf sheaths white, hyaline, fragile, the backs not white-spotted.
 ⇒ Carex gravida
1
Sheaths tight on the ventral side, neither septate-nodulose nor mottled with green and white on the dorsal side.

(c) Goldman, Douglas - CC-BY-SA
  5
Perigynia not conspicuously corky-thickened at base.

(c) Goldman, Douglas - CC-BY-SA
    6
Inflorescence ovoid in outline, the spikes densely aggregated, nearly indistinguishable except by the projecting setaceous bracts which subtend each spike.
      7
Perigynia 1.3-1.7× as long as wide, widest near the broadly rounded, truncate, or even subcordate base
 ⇒ Carex leavenworthii
      7
Perigynia 1.6-2.5× as long as wide, widest just below the middle, the base broadly cuneate to rounded.
        8
Pistillate scales (excluding the awns) shorter than the perigynium body; culms not greatly exceeding the leaves
 ⇒ Carex cephalophora
        8
Pistillate scales (excluding the awns) as long as or exceeding the perigynium body; culms much exceeding the leaves
 ⇒ Carex mesochorea
    6
Inflorescence spicate-racemose, the individual spikes readily distinguishable (often separated by an exposed internode of the axis).
      9
Pistillate scales brown or reddish-purple; [exotic, sparsely naturalized in our area].
 ⇒ Carex divulsa ssp. divulsa
      9
Pistillate scales green, hyaline, or pale tan; [native in our area (except C. austrina and C. muricata ssp. lamprocarpa), common and widespread in our area].
        10
Spikes with 8-20 perigynia; pistillate scales scarious-white (rarely brown) with green-veined center.
          11
Perigynia ascending, nerveless on the ventral surface; scales awned, the awns 1.5-4 mm long; lowest inflorescence bract elongate, the free portion 1-5 cm long
 ⇒ Carex austrina

(c) Campos, Aidan
(c) Goldman, Douglas - CC-BY-SA
          11
Perigynia spreading, either nerved or nerveless on the upper (ventral) surface; scales acuminate or with an awn to 1.5 (-2.0) mm long; lowest inflorescence bract short, delicate, the free portion 0.5-2 cm long.
             12
Perigynia 3.0-3.5 mm long, nerveless on the upper (ventral) face
 ⇒ Carex muehlenbergii var. enervis
  5
Perigynia corky-thickened in the lower 1/3 to 1/2 at maturity.

(c) Ward, Scott G
    13
Basal scales and sheaths purplish-tinted; perigynia ascending to spreading at maturity; [rare exotic]
 ⇒ Carex spicata
    13
Basal scales and sheaths light tan or brown; perigynia spreading or reflexed at maturity; [native species].
      14
Leaves 2.2-4.6 mm wide; perigynia 3.3-5.6 mm long, beaks (1-) 1.4-1.8 mm long
 ⇒ Carex perdentata
      14
Leaves 0.5-3 mm wide; perigynia not > than 4.0 long, beaks 0.3-1.2 mm long.
        15
Beak of perigynium smooth or serrulate; perigynia (2-) 3-12 (-20) per spike.
             17
Average perigynium width ≥ 1.3 mm; average spongy portion of the perigynium ≥ 1.1 mm long; perigynium base distinctly nerved, bulging on the ventral surface, making the perigynium biconvex in cross-section; perigynium 2-2.5× as long as wide; perigynium gradually narrowed to a short beak; leaves 1-3 mm wide
 ⇒ Carex retroflexa
             17
Average perigynium width < 1.3 mm; average spongy portion of the perigynium < 1.1 mm long; perigynium base nerveless, flattened on the ventral surface, making the perigynium planoconvex in cross-section; perigynium ca. 3× as long as wide; perigynium narrowed to a conspicuous beak; leaves 0.75-1.5 mm wide
 ⇒ Carex texensis
             18
Plants with creeping rhizomes, the culms arising scattered along the rhizome; perigynia 4-5× as long as wide
 ⇒ Carex socialis
             18
Plants densely cespitose, the culms arising from the center of clump; perigynia 2-3× as long as wide.
               19
Widest leaves 0.9-1.7 mm wide; base of fertile culm 0.7-1.4 mm wide.
                 20
Base of perigynium cuneate to rounded; distance from base of perigynium to base of achene 0.1-0.5 mm; [primarily of the Mountains in our area on dry soils]
 ⇒ Carex appalachica

(c) Powell, Eric M - CC-BY-NC, permission granted to NCBG
                 20
Base of perigynium rounded to truncate; distance from base of perigynium to base of achene 0.5-0.9 mm; [widespread in our area, soils typically mesic to wet]
 ⇒ Carex radiata

(c) Ward, Scott G
               19
Widest leaves 1.7-3.0 mm wide; base of fertile culm 1.4-2.2 mm wide.
                 21
Stigmas 0.03-0.06 mm thick, straight to slightly twisted; widest leaves < 2.0 mm wide; perigynia 3-7 (-8) per spike
 ⇒ Carex radiata
                 21
Stigmas 0.07-0.10 mm thick, mostly coiled; widest leaves > 1.7 mm wide; perigynia (6-) 7-14 (-20) per spike
 ⇒ Carex rosea