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Key to Tridens

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image of plant
Show caption*© Bruce A. Sorrie
1 Panicle dense and spike-like, > 4× as long as wide, the branches ascending to appressed.
  2 Plants from elongate rhizomes; lemma 4-5 mm long; spikelet 7-9 mm long
  2 Plants cespitose; lemma 2.5-3 mm long; spikelet 4-6 mm long
image of plant
Show caption*© Richard & Teresa Ware
1 Panicle open and spreading, < 4× as long as wide, the branches well-developed and spreading-ascending to reflexed.
    3 Midveins sometimes excurrent, the lateral veins not present as excurrent points (rarely reaching the distal margin of the lemmas); lower glumes 2.0-2.5 mm long (not mucronate).
    3 Midveins and (often also) the lateral veins of the lemmas both excurrent; lower glumes 4.0-4.5 mm long (if 2.5-3.0 mm long as in T. flavus and T. chapmanii, then the tips also usually mucronate).
      4 Spikelets 4-5 mm long, 2.5-3.5 mm wide; all pedicels shorter than 1 mm long
      4 Spikelets 6-8 mm long, 1.5-2.2 mm wide; pedicels > 1 mm long.
image of plant
Show caption*© Gary P. Fleming
        5 Primary pulvini densely pubescent, the hairs encircling the base of the panicle branch; secondary pulvini pubescent; spikelets mostly on pedicels 3-20 mm long, these divergent from the inflorescence branchlets; main branches of the inflorescence stiffly spreading
image of plant
Show caption*© Richard & Teresa Ware
        5 Primary pulvini glabrous to sparsely pubescent, tufted only in the axil (the upper surface of the panicle branch); secondary pulvini glabrous; spikelets on pedicels mostly < 3 mm long, these mainly appressed to the inflorescence branchlets; main branches of the inflorescence spreading, ascending or drooping