The common Sunflower is often seen along the Pennsylvania Turnpike, but also in urban lots. Originally a native of the Midwest, it springs up happily enough in Pittsburgh wherever anyone has been feeding sunflower seeds to the birds. If it grows tall enough, late in the season it produces many smaller flowers in the leaf axils, as here. This plant was blooming in early October on a hillside by one of Beechview’s many public stairways.
From Gray’s Manual: H. annuus L. (COMMON SUNFLOWER.) Tall, rough; leaves triple-ribbed ovate or the lower cordate, serrate; involucral bracts broadly ovate to oblong, long-pointed, ciliate; disk usually 2.5 cm. broad or more. Rich soil, Minn, to Tex., and westw.; long cultivated, and occasionally found in waste grounds eastw.