Flowers, plants, and herbs have been used as symbols since antiquity, but the romantic custom of using flowers to converse flourished after the 1819 publication in France of Charlotte de Latour's "Le Langage des Fleurs." In this enormously popular book, hundreds of flora were paired with translations, which ranged from heartwarming to heartbreaking. Courting couples used blooms to declare their affection when the strict etiquette of the time prohibited them from speaking openly, a method of communicating that became nearly an art. Over time many floral definitions have changed according to culture and whim.
Garden roses speak of love, carnations purer love, and tulips a declaration of love. Combining all three in a single bouquet sends a multi-layered message, spelling out three variants of the feeling. Other flowers have more specific meanings. Variegated tulips, for example, signal that the recipient has beautiful eyes; lavender can mean either luck or distrust (so exercise caution when using it in a bouquet), while geranium foliage symbolizes true friendship. A marguerite daisy sends a message of innocence, lady's mantle of comfort, mint signals virtue, and thyme strength and courage.