American sunflower

See the american sunflower my brother planted~~ So tall~ it's supposed to be able to grow to 2 men's height. I asked my mother to stand there to show its height in relative to her height. She is about 150cm tall.
I stood on a chair in an attempt to take a good look of the flower. But... even standing up on a chair, I am shorter than the flower. hahahahaha...