Silphium mohrii – Shaggy Rosinweed

General Information: This rare native, relative of sunflowers, sports large rosettes of basal leaves, followed by interesting pale yellow flowers. Each basal leaf can grow to nearly 1 foot long and around 5 inches wide. The flowers emerge in July and persist until fall, sometimes as late as November in warmer climates. Like other members of this genus, Shaggy Rosinweed is covered in scented resin-producing glands. These plants are imperiled in their native range by habitat loss. Home gardeners and landscapers alike can contribute to the conservation efforts of this species by growing these plants and producing seeds.

Cultivation Details: Self-fertile (only one is required to produce seeds). To collect seeds, harvest dried seed heads in October or November, when the inner flower parts begin to fall out. As with other members of the genus Silphium, but unlike other members of the Sunflower/Daisy Family, these plants have fertile ray florets (the “petals”) and sterile disc florets (the center). Seeds will only be found around the circumference of the flower head. These plants naturally occur on gravelly soils at the foothills of mountains and in prairies, indicating that the species is uniquely adapted to poor soils. Consider pairing with other selections from our “Attracts Wildlife” category. A unique and interesting addition to cottage gardens, wildflower gardens, prairie restorations, and pollinator gardens. Well-suited for mass plantings, roadside plantings, and for planting along fence lines and foundations.

Growing Requirements: Plant in full sun. Prefers well-drained soils, and is suitable for sandy or loamy soils. It is uniquely tolerant of dry, infertile gravelly soils; mildly acidic, neutral, and mildly alkaline soils.