The night blooming cereus flower bloom on the hillsides in Honolulu once a year. And, when one pops out, the entire hillside will fill with their white blossoms. The flower develops overnight and is wilting already in the morning making them quite elusive, but many put out noticeable buds a day or two in advance as if to indicate that their show is about to start.
If you visit Hawaii at the right time, you will find the cereus in the rainforests and along rock walls. They blossom from long cactus stalks which seem to grow like weeds. And, you will have to make a morning dash to find them before their flowers start to wilt.