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. 

Laetiflorus Characteristics

receptacle convex or low-conical

disk of flower heads purple, red, or dark brown

 

Helianthus Characteristics

receptacle flat or convex, not conic or columnar

receptacle with chaffy scales between the florets

flower heads with both tubular and ray florets

rays conspicuous

ray florets yellow