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Key to Cyperaceae

Cyperaceae

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1
Achene enclosed in a perigynium (a sac-like structure); [subfamily Caricoideae, tribe Cariceae]
 ⇒ Carex

(c) Marcum, Paul
1
Achene not enclosed in a perigynium.
  2
Scales obviously and strongly distichously imbricate; spikelets either aggregated into spikes or heads (Cyperus, Dulichium, Schoenus), or solitary (Abildgaardia); [subfamily Cyperoideae].

(c) Marcum, Paul
    3
Spikelets solitary and terminal (rarely 2-4); of FL peninsula in our area]
 ⇒ Abildgaardia ovata

(c) Horn, Jay
    3
Spikelets aggregated into terminal or axillary spikes or heads; [widespread in our area].
      4
Inflorescence axillary; leaves predominantly cauline, conspicuously 3-ranked; perianth bristles subtending the achene 6-9; [tribe Dulichieae]
 ⇒ Dulichium arundinaceum var. arundinaceum
      4
Inflorescence terminal, more-or-less scapose (though immediately subtended by leafy bracts); leaves predominantly basal, not 3-ranked; perianth bristles absent (Cyperus) or present (Schoenus); [tribe Cypereae].
  2
Scales spirally imbricate; spikelets not usually aggregated.

(c) Fleming, Gary P.
    6
Achene (when ripe) bony and white; style base persistent on the summit of the achene, forming a differently-textured or differently-colored tubercle; spikelets all unisexual, the pistillate spikelets 1-flowered, the staminate spikelets several-flowered; [subfamily Sclerioideae, tribe Sclerieae]
 ⇒ Scleria

(c) Horn, Jay
    6
Achene mostly brown, black, or tan; style base either persistent as a differentiated tubercle (Bulbostylis, Eleocharis, Rhynchospora) or not (Cladium, Eriophorum, Fuirena, Isolepis, Cyperus, Schoenoplectus, Scirpus, Trichophorum); spikelets mostly or all bisexual; [subfamily Cyperoideae].

(c) Flood, Melanie
      7
Style base persistent as a differentiated tubercle (this small and inconspicuous in Bulbostylis and some spp. of Rhynchospora).
        8
Leaves consisting of bladeless sheaths; spikelet 1 per stem, terminal (very rarely proliferating and with > 1 spikelet); [tribe Eleocharideae]
 ⇒ Eleocharis

(c) Ward, Scott G
        8
Leaves with well-developed blades; spikelets few to many per stem, usually subtended by foliaceous bracts.
          9
Perianth bristles absent; spikelets several-many-flowered; leaves capillary; [tribe Abildgaardieae]
 ⇒ Bulbostylis
          9
Perianth bristles present (rarely absent in species without capillary leaves); spikelets 1-2-flowered (several-many-flowered in some species without capillary leaves); leaves capillary to broad; [tribe Schoeneae]
 ⇒ Rhynchospora
        10
Achene not subtended by a modified perianth of bristles or scales (in addition to the scales of the spikelets).
          11
Involucral bracts 1-3, the lowest erect, appearing like a continuation of the culm, the inflorescence therefore appearing lateral.
             12
Achenes 0.5-0.7 mm long, 1.8-3× as long as wide, minutely papillose in longitudinal lines; [tribe Cypereae]
 ⇒ Cyperus
             12
Achenes 1.2-1.5 mm long, 1-1.4× as long as wide, minutely pitted or transversely rugose.
               13
Achenes transversely rugose; [tribe Fuireneae]
 ⇒ Schoenoplectiella
               13
Achenes minutely pitted in longitudinal lines; [tribe Cypereae]
          11
Involucral bracts 2-several, spreading, the inflorescence therefore appearing terminal.
             15
Plants diminutive, to 5 dm tall; leaves 3-15 cm long, < 1 mm wide; [tribe Abildgaardieae]
 ⇒ Bulbostylis
             15
Plants moderate to very robust, (3-) 5-30 dm tall; leaves 30-150 cm long, 1.5-15 mm wide.
               16
Flowers 1-2 per spikelet; [tribe Schoeneae]
 ⇒ Cladium
               16
Flowers several-many per spikelet.
                 17
Style fimbriate; leaves 0.5-5 mm wide; [tribe Abildgaardieae]
 ⇒ Fimbristylis

(c) Horn, Jay
                 17
Style smooth; leaves (2-) 5-18 mm wide; [tribe Scirpeae]
 ⇒ Scirpus georgianus
        10
Achene subtended by a modified perianth of either bristles, 3 stalked paddle-like scales, or 1-2 broad-based scales (in addition to the scales of the spikelets).
          18
Achene subtended by stalked paddle-like scales or broad-based scales.
             19
Achene lacking a perianth, but subtended by 1-2 broad-based scales; plants 0.5-3 dm tall; [tribe Cypereae]
 ⇒ Cyperus
             19
Achene subtended by a perianth of 3 stalked paddle-like scales; plants 2-7 dm tall; [tribe Fuireneae]
 ⇒ Fuirena
             20
Bristles 10-many, > 5× as long as the achene, white to tawny, straight; [tribe Scirpeae]
 ⇒ Eriophorum
             20
Bristles 1-6, usually < 4× as long as the achene, brown, straight or conspicuously twisted (twisted if > 3× as long as the achene).
               21
Involucral bracts lacking, or consisting only of the slightly modified basal scales of the solitary and terminal spikelet; [of hillsides, upland forests, or cliffs; never (in our area) in marshes, bogs, or streambeds]; [tribe Scirpeae]
 ⇒ Trichophorum
               21
Involucral bracts present, consisting either of a single, erect bract appearing as a continuation of the culm (the inflorescence thus appearing lateral) or of 2 or more spreading, foliaceous bracts (the inflorescence thus appearing terminal); [of marshes, bogs, streambeds, ditches, or (rarely) terrestrial or on rock outcrops].
                 22
Main involucral bract 1 (rarely 2), erect, appearing as a continuation of the culm (the inflorescence thus appearing lateral, though in some species the longer inflorescence branches may overtop the bract); [tribe Fuireneae]
                 22
Main involucral bracts 2-8, spreading and foliaceous (the inflorescence thus appearing terminal).
                   24
Spikelets 10-40 mm long, 6-12 mm in diameter, (1-) 2-40 (-50) per culm; [tribe Fuireneae]
 ⇒ Bolboschoenus
                   24
Spikelets 2.5-19 mm long, 2-4 mm in diameter, usually > 50 per culm; [tribe Scirpeae]
 ⇒ Scirpus