Ox-Eye (Sunflower Heliopsis; False Sunflower)
A clump-forming, spreading, branched, sunflower-like, short-lived perennial of variable height. Flowerheads about 2 inches across, distinctly orange-yellow when young, fading to light yellow; rays 8–15, usually 10. Blooms May–September. Leaves opposite on long petioles, broadly ovate to nearly triangular, without hair; with large, regular teeth. Seeds angular, while those of Helianthus species are flat.
Similar species: This is the only species of Heliopsis in Missouri. You can distinguish it from the many closely related true sunflowers (genus Helianthus) by its conical central disk and by its ray flowers, which dry out but persist, instead of withering and falling off.