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Key to Urochloa

Poaceae

Urochloa

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1 Spikelets with evident cross-venation throughout (cross veins not only confined to distal 1/2 of upper glumes or first lemmas); spikelets yellowish
1 Spikelets with longitudinal veins only, the upper glumes without cross-venation or cross-venation only on distal 1/2 of upper glumes; spikelets green or greenish-purple.
  2 Spikelets 1.8-2.2 mm long; plants annual and forming sprawling mats
  2 Spikelets 2.4-6 mm long; plants annual or perennial, erect or decumbent and rooting at nodes but not typically mat-forming.
    3 Pedicels bearing 1-5 long, conspicuous hairs.
      4 Spikelets solitary.
        5 Plants cespitose perennials; culm internodes with papillose-based hairs; secondary inflorescence branches present; lower glumes with 1-3 rigid hairs
        5 Plants erect to decumbent annuals (often rooting at lower nodes); culm internodes glabrous or sparsely pubescent; secondary inflorescence branches rarely present; lower glumes lacking rigid hairs
      4 Spikelets paired (at least at mid-branch length).
          6 Spikelets 4.8-6 mm long
          6 Spikelets 2.5-4 mm long.
             7 Spikelets suffused with purple
             7 Spikelets primarily green.
               8 Panicle branches glabrous to pubescent, with or without some papillose-based hairs; spikelets 2.5-3.4 mm long; upper glumes without cross venation distally; culm nodes pubescent
               8 Primary branches of panicles densely pubescent with papillose-based hairs; spikelets 3.2-4 mm long; upper glumes with evident cross venation distally; culm nodes glabrous or hispid
    3 Pedicels glabrous, scabrous or sometimes short-pilose, but not bearing long, conspicuous hairs.
                 9 Margins of upper glumes and lower lemmas uniformly pilose-fringed
                 9 Margins of upper glumes and lower lemmas glabrous or, if pilose, then the basal hairs shorter than the distal hairs (as in U. piligera).
                   10 Spikelets 2.9-3.8 mm long.
                     11 Spikelets paired, in 2-4 rows, the apices abruptly acuminate; glumes not spaced apart; leaf blades 7-20 mm wide
                     11 Spikelets solitary, in 2 rows, the apices acute or rounded; glumes 0.3-0.5 mm apart; leaf blades 3-10 mm wide
                   10 Spikelets 3.8-6 mm long.
                       12 Upper half of second glume and first lemma with evident transverse veins connecting the longitudinal veins
                       12 Upper half of second glume and first lemma without evident transverse veins.
                          13 Spikelets glabrous, 4.5-6 mm long; panicles 6-25 cm long; sheaths with papillose-based hairs
                          13 Spikelets usually pubescent, 3.8-4.9 mm long; panicles 3-12 cm long; sheaths lacking papillose-based hairs