Helianthus mollis (downy sunflower)

Perennial sunflowers have different sizes and leaf types, but they are all tough and assertive plants that produce golden flowers late in the growing season. Native to the Great Plains, downy sunflower is a fairly short species - it tops out at 5' - with grey-green, downy leaves. It prefers full sun and dry to medium soils, and tends to spread aggressively to form stands.

Photo credit: Eric Hunt