floriography
Communication through the use of flowers, with different types of flowers having particular symbolic meanings.
uncountable
Floriography is a science that requires but little study. Some flowers almost bear written upon their upturned faces the thoughts of which they are living representatives.
Where it comes from
From Latin flōris + English -o- + -graphy (suffix indicating something represented in the specified manner). Flōris is the genitive singular of flōs (“blossom, flower”), ultimately from Proto-Indo-European *bʰleh₃- (“blossom, flower”).
Adapted from the Wiktionary entry floriography (CC BY-SA 4.0).