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Key to Carduus

Asteraceae

Carduus

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1 Phyllaries 2-8 mm wide; heads mostly nodding (declined at least slightly from the vertical)
1 Phyllaries 1-2 mm wide; heads erect.
  2 Involucres spherical or hemispherical.
      4 Abaxial leaf blade surface with only curling, septate hairs; involucres 14-20 mm tall; disk corollas 13-20 mm long
      4 Abaxial leaf blade surface with dimorphic hairs (longer, curling septate hairs on the veins and sparse to dense tomentum across the surface); involucres 12-17 mm tall; disk corollas 11-16 mm long