Back in 2000 I received seed from North American Rock Garden Society seedlist of Saponaria cypria collected in the Troodos Mts of Cyprus. It is a seldom encountered endemic species. Just to let everyone know, it turns out this gem of a rock plant is perfectly hardy and easy to grow. Not only that, it flowers in late July to August, when little else is blooming. Of course this year, with our season 2-3 weeks advanced, it is beginning to flower in early July (now). The plant makes low mats 1-2" (2.5-5 cm) tall, and abundant sprays of pink flowers on 4-5" (10-12.5 cm) stems, showing off those long red sticky-glandular calyxes, even after the flowers fade.
In the small book "Cyprus Flora in Colour, The Endemics", it says of Saponaria cypria flowers, "opening in the evening and closing about noon of the following day". Not sure if we don't have the right night pollinators, or morning pollinators, but this plant has never set seed in spite of prolific flowering. I was going to take cuttings this spring, but forgot to do so.
This plant is difficult to photograph, the flowers opening under low evening light conditions, but hopefully you'll get the idea. I have included two photos of young flowering plants back in 2002 which do a better job of showing the long glandular red calyxes, which are as just as ornamental as the flowers.