Helianthus grosseserratus (Saw-tooth Sunflower)
Sawtooth sunflower is a striking late summer bloomer with awesome yellow flowers. CAUTION this plant is extremely aggressive for smaller landscapes. When used in the correct context it can be an awesome restoration tool.
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Photo Eric Hunt, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons