Crown

In Phoenix,  saguaros flower once every year, typically in May and June.
 Flowers are  about a three-inch-wide cluster of creamy white petals around a dense group of yellow stamens on about a four-inch-long stem. The saguaro has more stamens per flower than any other cactus flower. 
 Not all the saguaro cactus flowers bloom at the same time; several per day will bloom over the period of a few weeks. Saguaro blooms open at night and last through the next midday. Over a period of about a month, a few of the flowers open each night. They secrete a very sweet nectar into the flower tubes. Each flower blooms only once.