I'm a bit of a Cereus cactus addict. They only bloom one night each year, starting around sunset, and I always show up early to make sure I get as much photo-time with them as possible. There is a wonderful synchronized opening as it gets darker. The buds that minutes earlier were compact and wound up tight quickly unfurl in unison to create the incredible blossoms seen elsewhere in this gallery. The unwinding process is like a time-lapse of a flower opening, except it happens in real-time. You have to be quick with the camera, though. The flowers are changing rapidly as darkness approaches.