By Cinder Stanton, Center for Urban Habitats
Woodland Sunflower
Helianthus divaricatus
Family: Asteraceae
Average Height: 4 feet (range is 2-6 feet)
Bloom Time: June through August
Elevation Range: All elevations in the Piedmont
Geologic/Soil Associations: Typically found on bedrock that is rich in cations (rocks with dark minerals, such as metabasalt, gabbro, amphibolite, biotite-plagioclase gneiss, etc.). Shallow, dry, nutrient-rich soils
Soil Drainage Regimes: Mesic and Dry-mesic
Soil Moisture: Dry soil as well as well-drained moist soils
Aspect and Quality of Light: East, South, and West-facing upper slopes, partial sun, dappled light, and full sun
Habitat Associations: Basic Woodlands, Basic Prairie remnants and edge habitat along roads, and margins of Mafic Barren habitats.
Flora Associations: Frequently in association with Eupatorium sessilifolium, Lespedeza violacea, Dichanthelium boscii, Celtis tenuifolium, Solidago ulmifolia, Scleria oligantha, and Rosa carolina in Basic Woodland habitats and along the upper margins of flat rock outcrops. It forms extensive colonies in thin veneers of soil on bedrock under the shade of Cercis canadansis, Fraxinus americana, Carya glabra, and Juniperus virginiana.
Photo by Cinder Stanton
Fauna Associations: The flowers attract a wide variety of bees, wasps, flies, and butterflies. They are an important nectar and pollen source for native bees; some Andrena species — Andrena helianthi, for instance — are specialist pollinators of Helianthus. Among the invertebrates that feed on the foliage are the caterpillars of the butterflies Silvery Checkerspot (Chlosyne nycteis) and Painted Lady (Vanessa cardui). Seeds of H. divaricatus are eaten by Bobwhite and many other birds and small mammals.
Photo by Cinder Stanton
Notes:
- This species, often seen along roadsides, is an early-flowering sunflower that especially favors base-rich soils, such as the gneiss of the Ragged Mountains and the metabasalts of the Catoctin formation.
- It has hairless, or nearly hairless, stems and opposite leaves that are sessile (stalkless), or subsessile, and nearly truncate. The colonies formed by its creeping rhizomes harbor numerous other plant species and provide ground cover for many kinds of wildlife. It is a popular landscaping plant.
- The genus name comes from the Greek for sun (helios) and flower (anthos). The specific epithet means wide-spreading.
Photograph at top by Cinder Stanton
