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Key to Bromus

Poaceae

Bromus

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(c) Fleming, Gary P.
1 Lemmas compressed and strongly keeled (the whole spikelet thus strongly laterally flattened); first glume 3-9-nerved; [section Ceratochloa]
(c) Gunnar, Aaron - CC-BY
1 Lemmas rounded or weakly keeled (the whole spikelet therefore terete to somewhat laterally flattened); first glume either 3-5-nerved or 1-3-nerved.
(c) Ward, Scott G - CC-BY
  2 First glume 3-5 nerved (at least 3 nerves well-developed).
(c) Marcum, Paul
    3 Lemma awns 2-3 mm long; plants perennial; [native species of dry woodlands]; [section Bromopsis]
    3 Lemma awns 3-12 mm long (or 0-6 mm long in B. secalinus); plants annual; [introduced species of disturbed habitats]; [section Bromus].
(c) Weakley, Alan - CC0
      4 Panicle compact, the lateral branches erect or ascending (often densely ascendent in immature panicles), the pedicels < 10 mm long (shorter than the spikelets)
        5 Lemmas 11-20 long; spikelets 20-50 mm long; spikelets often arranged 2+ per inflorescence node; [LA and TX in our flora area]
        5 Lemmas 6.5-11.0 mm long; spikelets (11-) 12-25 mm long, usually 1 per inflorescence node (spikelet congestion can obscure this character); [collectively widespread in our flora area including LA and TX].
          6 Lemmas 3-5 mm wide; inflorescence ovoid in outline, branches not verticillate.
          6 Lemmas 1.5-2 mm wide; inflorescence obovoid in outline, the branches sometimes verticillate.
(c) Chytrý, Milan - CC-BY
      4 Panicle relatively open, the lateral branches erect, ascending, or spreading, the pedicels > 15 mm long (longer than the spikelets).
(c) Ward, Scott G - CC-BY
               8 Margins of the lemmas involute in fruit, wrapping around the grain, exposing the rachilla.
                 9 Spikelets often purple-tinged; lower leaf sheaths bearing soft, appressed hairs; lemma awns 6-11 mm long
                 9 Spikelets not purple-tinged; lower leaf sheaths glabrous, loosely pubescent and glabrate, or evenly pilose; lemma awns 0-6 mm (sometimes awns absent or rudimentary)
               8 Margins of the lemmas gaping, overlapping in fruit.
(c) Richardson, Dave - CC-BY
                   10 Panicle branches erect or ascending, relatively stiff and straight
                   10 Panicle branches spreading (at least the lower), either relatively stiff and straight, or flexuous and lax.
  2 First (lower) glume 1-nerved (occasionally with 3 nerves, but with only 1 nerve well-developed).
                       12 Longer lemma awns 10-60 mm long; plants annual; [introduced species of disturbed habitats]; [section Genea].
                            14 First glume 13-20 mm long; second glume 20-30 mm long; lemma awns 35-65 mm long
                            14 First glume 5-14 mm long; second glume 8-17 mm long; lemma awns 10-30 mm long.
                              15 First glume 7-14 mm long; second glume 9-17 mm long; lemma awns 18-30 mm long; branches of the panicles variable (drooping, spreading or ascending)
                              15 First glume 5-7 mm long; second glume 8-11 mm long; lemma awn (7-) 10-17 mm long; branches of the panicles drooping
                       12 Longer lemma awns 1-6 (-8) mm long; plants perennial; [native and introduced species, collectively of disturbed and natural habitats]; [section Bromopsis].
                                16 Plants with creeping rhizomes, forming clonal colonies; both surfaces of leaves glabrous or glabrescent
                                16 Plants not strongly rhizomatous, the stems solitary or tufted; surfaces of leaf blades usually pubescent (sometimes sparsely so).
                                  17 Pedicels erect or ascending, mostly shorter than the spikelets; leaves 2-3 mm wide; [introduced, of disturbed habitats]
                                  17 Pedicels ascending at first, later arching-drooping, mostly longer than the spikelets; leaves (3-) 4-15 mm wide; [natives of forests, seepages and brushy areas excluding B. ramosus].
                                    18 Lemmas primarily glabrous on the abaxial surface (sometimes scabrous or with hirsute marginally in B. ciliatus but not uniformly pubescent).
                                       19 Plants perennial; culms 45-120 (-150) cm tall; basal sheaths usually pilose but upper sheaths glabrous; awns of the lemmas 3-5 mm long; [primarily northeastern US southward in the mountains to NC in our flora area]
                                       19 Plants annual; culms 30-70 cm tall; sheaths densely pubescent to pilose throughout; awns of the lemmas 4-8 mm long; [endemic to s. TX and n. Mexico]; [section Bromopsis)
                                    18 Lemmas either uniformly pubescent over the entire back-surface (or rarely entirely glabrous), or hairy across at least the lower half of the back-surface.
                                         20 Culms with 6-20 leaves; glumes pubescent (sometimes glabrous in some species); [natives, collectively widespread].
                                           21 Culms with 10-20 leaves, often weak and leaning or reclining; junction of sheaths and base of leaf blades with 2 well-developed flanges prolonged into auricles or divergent spurs; second glume primarily 5-nerved; flowering late, with anthesis Aug-Oct
                                           21 Culms with 6-10 leaves, erect; junction of sheaths and base of leaf blades lacking flanges or auricles; second glume primarily 3-nerved; flowering earlier, anthesis from May-Aug.
                                             22 Lower surface of leaf with a conspicuous satiny sheen (when fresh); summit of sheath opposite the ligule with a conspicuous tuft of hairs; upper glumes often 5-veined
                                             22 Lower surface of leaf lacking a conspicuous satiny sheen; summit of sheath opposite the ligule lacking a conspicuous tuft of hairs; upper glumes 3-veined