The first few real summer nights, when the backyard is too enchanting to leave before dark, we wait for the evening primrose to open. The plant is a tidy rosette of jaggedy, dandelion-looking leaves, with a little flock of pointed, pale green buds bobbing six inches above.
The unfurling is easy to miss, if you are not there, reclining on the sidewalk with a cocktail in hand. The sheath splits, and then... Well, you can see for yourself, right here (this is in real time, not sped up).
I *believe* this is Oenothera flava or triloba or acutissima, but I am not sure of species. The song is Picador by Calexico, from the Hot Rail album.