WiseGeek’s page on growing moonflowers explains:
For a gardener who doesn’t keep a normal nine-to-five schedule, growing moonflowers may be the perfect hobby. Ipomoea alba, or the common moonflower, is a night-blooming vine from the same family as the morning glory. Growing moonflowers requires very little effort, and the gardener is rewarded with a climbing vine that can reach a height of 10 to 20 feet (3.05 to 6.1 meters) in one season. In its natural habitat of tropical and sub-tropical climates, this vine is considered a perennial, but in colder climates it must be replanted every year.
…As with their daytime cousins, the morning glories, growing moonflowers requires full or partial sun. The plant will begin to bloom in late afternoon and into the early evening hours, and continue to remain open until sunrise. The vines are voracious climbers, and should be planted in a spot where they may spread as needed, such as near a trellis or patio support beam.
Moonflowers produce large white flowers. Some gardeners like to grow them alongside various colors of morning glories, especially the “heavenly blue” strain. This commingling results in an abundance of flowers both day and night in one garden spot, blue in daylight and white by moonlight. The fragrant moonflowers are often considered ornamental, and each flower remains open no longer than one night.
Many (many) more Michigan flowers on Michigan in Pictures!