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Key to Poaceae, Key L: grasses with 1 floret and awned lemmas

Poaceae

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1 Lemma awn 3-branched (the lateral 2 sometimes very reduced compared to the central); [tribe Aristideae]
1 Lemma awned with a simple awn.
  2 Upper glumes present, 1-veined; lower glumes absent or much shorter than the upper glumes and veinless; [tribe Brachyelytreae]
  2 Both glumes present, 1-many-veined.
    3 Lemma hardened, distinctly different than the glumes in texture when mature; [tribe Stipeae].
      4 Rhizomatous perennials; primary leaves cauline (the basal leaves < 2 cm long or merely represented by sheaths), 8-16 mm wide
      4 Cespitose perennials; primary leaves basally disposed, 0.2-10 mm wide.
        5 Leaves > 4 mm wide.
          6 Florets 2.5-3.5 mm long; awns 3.4 mm long; [exotic, rarely naturalized]
          6 Florets 5-13 mm long; awns either 7-15 or 30-120 mm long; [exotics or natives].
             7 Leaves 2-8 mm wide, not twisted at the base; awns 30-120 mm long
             7 Leaves 4-10 mm wide, the base twisted so that the abaxial surface is uppermost; awns 7-15 mm long
        5 Leaves < 4 mm wide.
               8 Florets 7-25 mm long; awns 30-225 mm long.
                 9 Palea grooved, longer than the lemma; lemma margins involute, fitting into the paleal groove; [native species, collectively widespread in our area]
                 9 Palea flat, shorter than or equal to the lemma; lemma margin convolute or not overlapping; [exotic species, rare in our area]
                   10 Lemma margins not or only slightly overlapping at maturity; awns 60-190 mm long
                   10 Lemma margins strongly overlapping for their entire length at maturity; awns 40-120 mm long
               8 Florets 1.5-4.5 mm long; awns 1-35 mm long
                     11 Leaves 0.2-0.6 mm wide; florets 1.5-2.5 mm long; awns 15-35 mm long
                     11 Leaves 0.5-10 mm wide; florets 2.2-4.5 mm long; awns 1-15 mm long.
                       12 Leaves 0.5-1.8 mm wide; central vein of the lemma not prominent; [native species]
                       12 Leaves 2-10 mm wide; [rare exotic species]
    3 Lemma neither hardened nor distinctly different than the glumes in texture when mature.
                          13 Spikelets 18-32 mm long; [tribe Poeae]
                          13 Spikelets 1.1-8 mm long.
                            14 All spikelets sessile or subsessile and arrayed along inflorescence axes (racemes) divergent from the central axis (but not both overlapping one another and clearly ranked on one side of the axis, so as to be keyed under Key H).
                              15 Inflorescences with disarticulating branches; Lower glumes 0.9-4 mm long; spikelets disarticulating below the glumes, the spikelet falling as a whole; spikelets appressed to divergent from the raceme axes; sheaths not strongly overlapping; [tribe Cynodonteae; subtribe Eleusininae]
                              15 Inflorescences without disarticulating branches; lower glumes 1.5-3 mm long (Muhlenbergia paniculata) or (2-) 3.5-7 mm long (Gymnopogon); spikelets disarticulating above the glumes (which often remain on the inflorescence); spikelets strongly appressed to the raceme axes; sheaths strongly overlapping or not , if so then at least on the upper culm, therefore hiding the culm; [tribe Cynodonteae; subtribe “incertae sedis”]
                                16 Blades with thick, white margins and well-developed midrib; inflorescence branches strongly divergent; glumes unequal, usually shorter (sometimes only slightly so) than the solitary floret
                                16 Blades lacking both thick, white margins and well-developed midribs; glumes subequal, usually exceeding the 1-2(4) floret(s)
                            14 Spikelets pedicellate and arrayed in a more complex, open (and sometimes loosely contracted) panicle.
                                  17 Lemma surrounded by a tuft of callus hairs; [tribe Poeae]
                                  17 Lemma not surrounded by callus hairs.
                                    18 Spikelets disarticulated below the glumes, the spikelet falling intact, leaving a naked pedicel; [tribe Poeae]
                                       19 Lemma awns 5.0-14.5 mm long; culms to 60 cm tall; plants tufted annuals
                                    18 Spikelets disarticulated above the glumes, the floret falling, leaving the glumes attached to the pedicels.
                                         20 Lemmas faintly 5-veined; awn from the back of the lemma; lower glume longer than the lemma; palea much shorter than the lemma (or absent); [tribe Poeae]
                                         20 Lemmas strongly 3-veined; awn from the tip of the lemma; lower glume shorter than (rarely equaling) the lemma; palea about equaling the lemma; [tribe Cynodonteae; subtribe Muhlenbergiinae]