This is the bloom of the Celestial or Ghost Iris, although the USDA (http://plants.usda.gov/core/profile?symbol=NEGE ) calls this species the Praire Pleatleaf. Nemastylis geminiflora is a perennial wildflower in the Iridaceae family (irises) that is found throughout Texas. They are small plants 6 to 18 inches tall and they like dry calcareous soils. Each flower lasts for a single day. This flower is one of my favorite wildflowers because of its petal color contrasted with the yellow stamens. Look for them blooming March through May.