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Key to Paspalum

Poaceae

Paspalum

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1 Both lower and upper glumes absent, or upper glume present on terminal spikelet only of a panicle branch.
  2 Plants stoloniferous; culms to 40 cm long; blades to 4 mm wide; spikelets 3.8-5.2 mm long, apex acuminate; upper glume sometimes present on terminal spikelet of a panicle branch
  2 Plants cespitose; culms to 200 cm long; blades to 35 mm wide; spikelets 1.8-2 mm long, apex obtuse; both glumes absent from all spikelets
1 At least upper glume present on all spikelets.
    3 Spikelets solitary, not associated with rudimentary spikelets or naked pedicels.
(c) Horn, Jay
      4 Panicles usually composed of a terminal pair of branches, sometimes with 1 (-5) additional branches below the terminal pair.
(c) mark-groeneveld - CC-BY
        5 Upper glumes pubescent on the back or margins.
          6 Spikelets 1.3-1.9 mm long; upper glumes pilose along the margins; ligules 0.5-0.8 mm long; panicle branch axis 0.2-0.8 mm wide
          6 Spikelets 2.4-3.2 mm long; upper glumes sparsely pubescent on the back; ligules 1-2 mm long; panicle branch axis 1.2-2.2 mm wide
(c) Wright, Janet - CC-BY-NC, permission granted to NCBG
        5 Upper glumes glabrous.
               8 Plants short-rhizomatous, culms appearing cespitose; blades to 4 mm wide; spikelets 3-3.6 mm long; lower lemmas 5-veined; upper florets stramineous to golden brown; most frequently found along roadsides and in pastures
               8 Plants rhizomatous, the culms separate; blades to 8 mm wide; spikelets 3-4.5 mm long; lower lemmas 3-veined; upper florets white; most frequently found in brackish and salt marshes
                 9 Culms to 60 cm long; blades flat; panicle branches to 6.4 cm long; spikelets 1.9-2.3 mm long, 1.2-2 mm wide; upper glumes 3-veined
                 9 Culms to 120 cm long; blades flat or longitudinally folded; panicle branches to 15 cm long; spikelets 2.5-4 mm long, 2-2.8 mm wide; upper glumes 5-veined
(c) Faccenda, Kevin - CC-BY
      4 Panicles with 1-70 branches; if > 1, the branches arranged racemosely, the 2 uppermost not paired.
(c) Fleming, Gary P.
                   10 Panicle branches 7-70, the axes extending beyond the outermost spikelets; panicle branches disarticulating at maturity
(c) Tasney, Greg - CC-BY-SA
                   10 Panicle branches 1-6, terminating in a spikelet; panicle branches persistent.
© Scott Ward
                       12 Axes of panicle branches not broadly winged, 0.6-1.3 mm wide.
(c) Johnson, Dan - CC-BY
                       12 Axes of panicle branches broadly winged, 1.8-3.3 mm wide.
                            14 Culms to 100 cm long; spikelets 3.2-4 mm long, 1.6-1.7 mm wide; upper lemmas with a few short hairs at their tips; caryopses 2-3 mm long
                            14 Culms to 50 cm long; spikelets 1.7-2.1 mm long 1.1-1.4 mm wide; upper lemmas glabrous; caryopses 1-1.3 mm long
    3 Spikelets paired, or at least the second nonfunctional spikelet represented by a naked pedicel.
(c) Bradley, Keith
                                    18 Culms to 70 cm long; upper glumes and lower lemmas broadly winged, the wing fimbriate; spikelets 2.4-3 mm wide
                                    18 Culms to 220 cm long; margins of upper glume and lower lemmas long-ciliate, wingless; spikelets 1.1-2.5 mm wide.
                                           21 Plants either not aquatic OR if aquatic then with erect culms; lower glumes absent.
                                               23 Plants annual; axes of panicle branches broadly winged, the wings about as wide as the central portion; [common native]
                                               23 Plants perennial; axes of panicle branches narrowly winged, the wings narrower than the central portion; [rare exotics].
                                                          28 Rhizomes indistinct or absent; ligule 1-4.1 mm long; panicle branches to 11 cm long; mature lower lemma not transversely rugose.
                                                              30 Plants annual; culms to 53 cm long; blades to 12 mm wide, flat; ligules 2-4.1 mm long; branch axes 0.8-1.3 mm wide; spikelets 2.1-2.6 mm long
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Key to Paspalum, Key A: Paspalum setaceum complex
(by Richard J. LeBlond)

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1 Blades glabrous to pubescent or sparsely pilose (the margins often ciliate and/or scabrous).
  2 Blades glabrous, crowded toward the base, often recurved, 3-10 mm wide; rachis of panicle branches 0.2-0.6 mm wide; spikelets 1.4-1.8 mm long, 0.9-1.3 mm wide, glabrous (-few glandular hairs); sterile lemma without a midvein
  2 Blades glabrous, sometimes pubescent or sparsely pilose, more strongly cauline, not recurved (though sometimes spreading), 3-18 mm wide; rachis of panicle branches 0.6-1.2 mm wide; spikelets 1.7-2.6 mm long, 1.2-2.1 mm wide, pubescent to glabrous; sterile lemma with or without a midvein.
    3 Blades conspicuously rigid, 2.5-6 (-8) mm wide; spikelets 2.0-2.6 mm long, 1.5-1.8 mm wide
    3 Blades lax to firm (if firm, then more than 6 mm wide); spikelets 1.7-2.4 mm long, 1.2-2.1 mm wide.
      4 Sterile lemma with a midvein; blades dark green to purple; spikelets elliptic to obovate, 1.7-2.0 mm long, 1.2-1.5 mm wide
      4 Sterile lemma without a midvein; blades yellow-green to dark green; spikelets obovate to suborbicular, 1.7-2.4 mm long, 1.5-2.1 mm wide
1 Blades densely pubescent, hirsute, or long pilose.
        5 Blades crowded toward the base, recurved; spikelets 1.4-1.9 mm long, often purple-spotted
        5 Blades more strongly cauline, not recurved (though sometimes spreading); spikelets 1.4-2.5 mm long, not purple-spotted.
          6 Plants prostrate to widely spreading; rachis of panicle branches 0.6-1.5 mm wide.
             7 Blades 3-8 mm wide, grayish green, densely pubescent with hairs < 1.5 mm; panicle branches 3-6 cm long, rachis 0.7-1.0 mm wide; spikelets 1.8-2.2 mm long, 1.6-1.8 mm wide, suborbicular to orbicular, pubescent; sterile lemma without a midvein
             7 Blades 2-19 mm wide, yellow-green, pilose with hairs 1.5-4 mm long; panicle branches 2-10 cm long, rachis 0.6-1.5 mm wide; spikelets 1.7-2.1 mm long, 1.2-1.6 mm wide, elliptic to obovate (-suborbicular), glabrous or pubescent; sterile lemma with or without a midvein
          6 Plants erect to spreading; rachis of panicle branches 0.3-1.0 mm wide.
               8 Spikelets 1.4-1.9 mm long, 1.1-1.6 mm wide; sterile lemma without a midvein; blades grayish green, 1.5-7 mm wide
               8 Spikelets 1.7-2.5 mm long, 1.5-2.1 mm wide; sterile lemma with or without a midvein; blades light green or yellow-green to dark green, 2-16 mm wide.
                 9 Sterile lemma usually with a midvein; blades 2-10 mm wide, hirsute with hairs to 5.5 mm long, light to dark green; spikelets glabrous to sparsely pubescent