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Key to Festuca

Poaceae

Festuca

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1 Plant annual (easily uprooted); stamen 1.
© Scott Ward
  2 First glume < ½ as long as the second glume
  2 First glume > ½ as long as the second glume.
    3 Lemma pubescent; lowest lemma 2.5-3.5 mm long; grains 1.5-2 mm long
    3 Lemma glabrous or scabrous; lowest lemma 2.7-7 mm long; grains 1.7-3.3 mm long.
      4 First glume 1.7-4.5 mm long; lemma awns 3-12 mm long; spikelets with 4-7 loosely imbricate florets; rachilla internodes mostly 0.9-1.1 mm long
      4 First glume 3.5-5 mm long; lemma awns 0.3-6 (-9) mm long; spikelets with 5-11 (-more) closely imbricate florets; rachilla internodes mostly 0.5-0.7 mm long.
        5 Spikelets 4-5.5 (-6.5) mm long; awn of the lowest lemma 0.3-3 mm long
        5 Spikelets 5.5-10 (-13) mm long; awn of the lowest lemma 3-9 mm long.
          6 Lemmas scabrous to pubescent; [TX and OK, westward as a native, introduced in n. FL]
          6 Lemmas usually smooth, sometimes scabridulous distally and marginally; [widespread]
1 Plant perennial (firmly rooted); stamens 3.
             7 Leaves 0.2-3 mm wide, often involute or conduplicate.
               8 Plants loosely tufted, often rhizomatous; basal sheaths disintegrating into fibers; spikelets 6-13 mm long
               8 Plants tufted, lacking rhizomes; basal sheaths usually persistent, remaining firm and entire; spikelets 3-9 (-10) mm long.
                 9 Lemmas 2.3-4.0 (-4.4) mm long, awnless, or with a minute projection (mucro) to 0.4 mm long; spikelets 3.0-6.0 (-6.5) mm long
                 9 Lemmas (3-) 3.4-5.5 mm long, with an awn 0.5-2.5 mm long; spikelets 4.5-9.0 mm long
                   10 Anthers 0.8-1.8 mm long; lower panicle branches strongly ascending; [high elevation boreal habitats, NY northward]
                   10 Anthers 1.8-2.6 mm long; lower panicle branches often spreading; [widespread in a variety of habits in e. and w. US]
(c) Marcum, Paul
             7 Leaves (2-) 3-12 mm wide, flat (flat, conduplicate or involute in Festuca versuta).
                     11 Larger lemmas 5.5-10 mm long; leaf blades auriculate at the base (except Festuca versuta); anthers 2-4 mm long
                       12 Leaf blades auriculate at the base, held flat, loosely conduplicate, or involute; [scattered from se. KS and nw. AR south into OK, disjunct southwards on the Edwards Plateau]
                          13 Auricles ciliate (sometimes only very sparsely so – check several at 10-20× magnification); spikelets with 3-6 (-9) florets; old sheaths pale straw-colored, often remaining intact; internodes of the rachilla antrorsely scabrous
                          13 Auricles glabrous; spikelets with (2-) 4-10 (-12) florets; old sheaths brown, decaying to fibers; internodes of the rachilla glabrous (smooth) or nearly so
(c) Marcum, Paul
                     11 Larger lemmas 3.3-5.2 mm long; leaf blades not auriculate at the base; anthers 0.8-1.5 mm long; [subgenus Subulatae, section Obtusae].
                            14 Ligules 0.1-1.5 (-2) mm long; [common natives].
                              15 Principal lowermost panicle branches with 8-20 spikelets clustered at the end; spikelets broadly ovate, 4-6 mm wide
                              15 Principal lowermost panicle branches with 2-7 spikelets scattered along the outer half; spikelets narrowly ovate, 2-4 mm wide