A corsage is a single flower or several small flowers worn pinned onto clothing or on an elastic band around the wrist. The flowers are usually worn to indicate a special person on a special day, such as a groom on his wedding day or a girl going to her prom.
A boutonniere is the male equivalent of the female corsage. The boutonniere is usually a collection of one or two small flowers, with perhaps an accent of a bit of baby’s breath or fern. Most often, the boutonniere is worn for formal occasions, such as weddings or proms. It is always pinned to the left lapel of the tuxedo or suit.