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Key to Alternanthera

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1 Inflorescences borne on peduncles 1-7 cm long, these from the leaf axils or terminal.
image of plant
Show caption*© Joe MDO, some rights reserved (CC BY-NC), uploaded by Joe MDO
  2 Bracts keeled; tepals pilose or villous; leaves not succulent, acute to acuminate at the tip.
    3 Young stems and leaves pubescent, strigose or glabrous; bracts < 1/2 as long as tepals; peduncle 3-6 cm long; [common native of coastal, saline habitats]
    3 Young stems and leaves villous; bracts slightly shorter than or equaling tepal length; peduncle 1-2 cm long; [uncommon native]
image of plant
Show caption*© Richard & Teresa Ware
  2 Bracts not keeled; tepals glabrous; leaves somewhat succulent, obtuse to rounded at the tip
1 Inflorescences sessile, in the leaf axils.
image of plant
Show caption*© Scott Ward, dimorphic tepals
      4 Tepals dimorphic; tepal hairs barbed.
        5 Leaf blades longer than broad; tepals 3-5 mm long, densely villous
        5 Leaf blades as broad as long; tepals 5-7 mm long, sparsely villous
image of plant
Show caption*© Scott Ward, monomorphic tepals
      4 Tepals monomorphic; tepal hairs not barbed.
          6 Pseudostaminode margins fimbriate; anthers 5, oblong.
             7 Young stems pubescent; leaves not succulent; tepals chartaceous, pilose to hispid; [non-native, disturbed habitats]
             7 Young stems glabrous; leaves succulent; tepals rigid, glabrous; [native, coastal habitats]
          6 Pseudostaminode margins entire, dentate, or laciniate; anthers 3-5, globose.
               8 Mature fruit included within the tepals; spikes globular; stems sericeous
               8 Mature fruit exserted between the tepals; spikes narrow, short-cylindric; stems glabrous to pubescent in lines (the nodes also pubescent)