Description and General Information:
Once known as O. missouriensis, the Ozark or Missouri sundrops is native to Nebraska and Kansas, where is grows on limestone bluffs and rocky prairies. Plants have a sprawling habit and reach 15-30 cm high. The subspecies fremontii has narrow, elongate leaves with a silver shimmer. The solitary flowers are quite large for the size of the plant, measuring 7-10 cm in diameter, with four broad, yellow petals. Flowers last a single day, opening in late afternoon then fading the next morning. The blooming season ranges from May to September.
This species requires full sun and a well-drained site. It is particularly sensitive to excess winter-wet. It is tolerant to drought and clay soils. Plants will be more compact if grown in poor soils. It prefers alkaline soils and is hardy through zone 3. It is generally pest and disease-free.
Plants bloom from late spring to late summer, depending on the location.
Primarily by seeds, less commonly by cuttings.
Seeds usually germinate freely if sown at 20 C, but if seed does not germinate within a couple of months, try exposing them to cold for 1-2 months.
Not generally practiced.
Stem cuttings (preferably non-flowering shoots) may be taken in mid-summer.