The language of flowers was developed in the Ottoman Empire, centuries ago. The „language” of messaging by flowers reached Western Europe in 1717, but its real boom and heyday was in the 1800s. The strict morals of the Victorian Europe didn’t allow for the lovers to talk open about their feelings or even stay téte-á-téte. That’s why the language of flowers became the perfect tool for sending messages and express emotions (both positive and negative).
Several books were published in the subject in the 19th century, providing a complete dictionary for the readers. This knowledge was part of the good education. Almost every flower had its own meaning, sometimes more meanings. Some varieties had meanings by colors (e.g. rose, tulip, carnation). Multi-sentenced confessions could be sent with a perfectly made bouquet. The method of accepting the present flower (bouquet) had a message also. If it was kissed, that meant yes. If a petal was torn, that meant no.
The meanings of some of them are well known still today: red rose = love, white lily = innocence, violet = modesty. Maybe these are less known: campanula = humbleness, blue hyacinth = perseverance, yellow rose = friendship.
Hundreds of flower dictionary were published which weren’t unified at all. The meaning of a flower might be different by countries or counties. So, if somebody wanted to send a message that way in a foreign country, it was worth to orient himself/herself about the local „dialect” before doing it, otherwise he/she could get in a predicament.
The beginning of the WWI was the turning point that was the time when the usage of flower language almost finally died. Nowadays only red rose is given as a certain symbol.