Answer: Sawtooth Sunflower, Helianthus grosseserratus, is an Illinois native. Helianthus maximiliani is the Prairie or Maximillian sunflower. Maximilian and sawtooth sunflowers are so close to identical I can't tell them apart but sawtooth sunflowers bloom a little sooner and the well-bred Maximilians have more flowers.
These plants are perennials and will grow 36-72 inches tall and about 40 inches wide.
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