Maximillian's Sunflower Asteraceae.
This North American native sunflower is a very large and showy species with many bright yellow flowers that have yellow(turning dark) centers. Plants grow from 4 to 8 (10) feet tall and bloom in late summer-late fall, after flowering is done the seeds are feed upon by migrating birds. Best grown in dry sandy, loamy, or clay soils. Drought tolerant. Not as much a spreader as 'Showy Sunflower' but seedlings can grow in the smallest spot between rocks and the edging of borders if the birds don't get all the seeds first. In some areas plants grow so large they often “flop,” a hard shearing in early July will make a fuller but shorter plant that does not so readily flop under windy conditions.