Helianthus laetiflorus

Beautiful Sunflower

3 Miles North of Antler
17-Aug-2002

I have found that neither flora easily distinguishes between Helianthus and Rudbeckia (Rudbeckia hirta is Black-eyed Susan) in their keys.  However, they do note that the receptacles of Rudbeckia are more conic. 

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Laetiflorus Characteristics
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receptacle convex or low-conical

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disk of flower heads purple, red, or dark brown

 

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Helianthus Characteristics
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receptacle flat or convex, not conic or columnar

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receptacle with chaffy scales between the florets

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flower heads with both tubular and ray florets

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rays conspicuous

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ray florets yellow