Helianthus divaricatus aka Woodland Sunflower

The woodland sunflower has the scientific name Helianthus divaricatus. Another name for it is rough sunflower. This plant belongs to the daisy family. It lives for years and has no woody stems. Its native range covers southeastern Canada. It also spans much of the eastern United States. The plant grows in the north-central United States, too. In the wild, it grows in woods and thickets. It also grows in dry clearings. These sites often have sandy or rocky ground.

Plants reach 2–6 feet (0.61–1.83 metres) tall. They spread 1–3 feet (0.30–0.91 metres) wide. Stems grow upright in clumps and branch near the flowers. Rhizomes, or creeping underground stems, help the clumps spread. They form larger groups called colonies. Growth is fast, and these groups can spread with force. The thin, round stems range from light green to purple. Some have a pale, waxy coat. Most stems have no hairs, though some have a few.

Pairs of simple leaves grow along the stems. Their shape ranges from lance-like to oval or oblong. Leaves reach 6 inches long and have pale undersides. Their tops feel rough, and soft hairs cover their undersides. Leaf edges may be smooth or have a few teeth. Leaves join the stem with no stalk or very short stalks. These short stalks help tell this species from other sunflowers.

Yellow flower heads bloom from July through September. Some plants may bloom earlier in summer. Each head measures about 1.5–3 inches across. Bright yellow rays ring a disk of deeper yellow. Small, tube-shaped flowers, called florets, form the disk. Green bracts, or leaf-like parts, overlap beneath each head. Flat, oval fruits called achenes follow the flowers. They ripen in fall and turn dark brown to black. Butterflies and other insects visit the flowers for nectar. The plant serves as a host for silvery checkerspot caterpillars. Birds and small mammals eat its seeds.

Woodland sunflower grows in sun or partial shade. It suits shaded borders and woodland gardens. It also fits plantings of native plants. Large groups suit meadows and sites left to grow wild. The flowers work well as fresh-cut flowers for display. Plants grow in USDA zones 3–8. They need soil that drains well. They accept many soil types, including sand and loam. They grow in dry to moist ground. Once plants take hold, they can withstand drought. They need little care. Reports note no major pest or disease concerns. Deer resistance helps where deer feed on plants. Tall stems may need stakes to stay upright. Divide clumps every three to four years. This curbs their spread and keeps plants growing strongly.