Asteraceae: Heliopsis helianthoides
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Family Name
Asteraceae
Common Name
Smooth oxeye, false sunflower
Description
Heliopsis helianthoides is a perennial herbaceous plant that grows from a fibrous root system with creeping rhizomes that form dense clumps or colonies over time. The stems are erect, branching and typically reach 60 to 150 cm tall. Leaves are opposite or alternate, ovate to lanceolate, measuring 7 to 15 cm long and 3 to 7 cm wide. The leaf margins are serrated with coarse teeth, and the surface is rough to the touch. Leaves have pointed tips and tapering bases, attaching via short petioles. The plant has a bushy habit. Flowering occurs from mid to late summer (July–September). Inflorescences consist of bright yellow, daisy-like flower heads about 4–7 cm across. Each flower head is surrounded by several series of green, lanceolate to ovate involucral bracts about 10 to 15 mm long, often with fine hairs. The ray florets number about 10 to 20, with petals that are oblong to spatulate, measuring 2.5 to 4 cm long and 5 to 10 mm wide, with smooth edges. Disc florets are tubular, perfect (bisexual), about 3 to 5 mm long, with five lobes at the corolla tip. Stamens are fused into a tube around the style, which divides into two stigmatic branches. The fruit is a small, dry achene, 3 to 4 mm long, with no pappus or with a pappus of short hairs, that matures in late summer. Smooth oxeye is native to South Dakota and commonly found in prairies, open woodlands, and along roadsides and disturbed sites across the state.
Horticulture Notes
Seed Collection: Seeds mature in late summer when flower heads dry; harvest seeds by removing dried heads.
Germination: Seeds germinate readily without special treatment; sow in spring on well-drained soil.
Vegetative Propagation: Can be propagated by division of mature clumps in spring or fall.
Soils: Prefers well-drained, moderately fertile soils.
Light: Thrives in full sun to partial shade.
Water: Prefers moderate moisture but tolerates occasional dry periods.
Additional Notes
Smooth oxeye attracts a variety of pollinators including bees and butterflies. This species is popular in native plant landscaping and restoration projects due to its showy flowers and adaptability.