What has floriography been used for?

The significance assigned to specific flowers in Western culture varied – nearly every flower had multiple associations, listed in the hundreds of floral dictionaries – but a consensus of meaning for common blooms has emerged. Often, definitions derive from the appearance or behavior of the plant itself. For example, the mimosa, or sensitive plant, represents chastity. This is because the leaves of the mimosa close at night, or when touched. Likewise, the deep red rose and its thorns have been used to symbolize both the blood of Christ and the intensity of romantic love, while the rose's five petals are thought to illustrate the five crucifixion wounds of Christ. Pink roses imply a lesser affection, white roses suggest virtue and chastity, and yellow roses stand for friendship or devotion. The black rose (in nature, a very dark shade of red, purple, or maroon, or may be dyed) may be associated with death and darkness due to the traditional (Western) connotations of the shade.