This is a photo of the same cactus taken in April. The brilliant red color and full petals are a real contrast to the pitiful little June 23 flower.
The Euphorbia milli 'Dinni' suddenly put out a few flowers this week. They are sparse, but will last for days.
Then there's my old reliable Gymnocalycium baldianum. It blooms from April through September, no matter how hot it gets. The flowers last a few days, and then it takes a rest for a few days. New buds form and another round of flowers appear. This happens repeatedly for six months.