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Key to Leersia

Poaceae

Leersia

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1
Spikelets 1.5-2 mm long, spikelets glabrous; plants cespitose, lacking rhizomes; [FL and TX southwards]
 ⇒ Leersia monandra
1
Spikelets 2.5-6.5 mm long; spikelets ciliate on the keels and margins; plants with short to elongate rhizomes; [collectively widespread].
  2
Lower panicle branches whorled or closely approximate; spikelets 4.0-5.5 mm long, 1.5-2.0 mm broad; stamens 3
 ⇒ Leersia oryzoides
  2
Lower panicle branches alternate (rarely opposite); spikelets 2.2-5.0 mm long, 0.8-4.0 mm broad; stamens 2 or 6.
    3
Spikelets suborbicular-falcate, 3.0-4.0 mm broad, < 2× as long as broad; principal leaf-blades 10-15 mm wide; stamens 2
 ⇒ Leersia lenticularis
    3
Spikelets narrowly elliptic-falcate, 0.8-2.0 mm broad, > 2× as long as wide; principal leaf-blades usually < 7 mm wide; stamens 2 or 6.
      4
Spikelets 3.8-4.7 mm long, 1.5-2.0 mm broad; panicle branches short, bearing spikelets nearly to their bases; stamens 6
 ⇒ Leersia hexandra
      4
Spikelets 2.2-3.5 mm long, 0.8-1.2 mm broad; panicle branches long, filiform, the longer ones bearing spikelets only in their upper half; stamens 2
 ⇒ Leersia virginica