Swamp Sunflower (Helianthus angustifolius) is a 5- to 8-foot perennial with profuse 2- to 3-inch yellow daisy-like flowers from August until the first frost. If the plants are pruned a bit in June they will branch out. in June to encourage branching. It will tolerate part shade but flowers better in full sun.

This is a larval host plant that supports silvery checkerspot (Chlosyne nycteis), a species of special concern in Connecticut. Other butterflies and specialized bees are attracted to the nectar and pollen. Leave the dead flowers in fall to provide winter food for songbirds, Mourning Doves, and small mammals. Deer do not like swamp sunflower.