Not sure if this is what you meant, but the Victorians used to use flowers as a code to communicate with lovers. Couldn't find a flower which specifically meant "you have bad breath", but here is a list which you may be able to use to say something to that effect.
Bittersweet (Nightshade, Woody)
Truth
Bay Tree (Laurel)
Sharpness
Burdock
Importunity, Touch me not
Dragonswort
Geranium, Fish
Disappointed expectation
Henbane
Imperfection
Hyssop
Cleanliness
Tussie Mussie
Fragrance remembered
Carnation (Yellow)
Disdain, Rejection
The Yellow Poppy is the flower that symbolizes family. Another flower than can stand for family is the Iris flower.
LOTUS
Geraniums
The thistle
The Almond Blossom symbolizes HOPE, sweetness and delicacy.
the lotus flower symbolizes the nile river
mine
Sorrel :)
Heliotrope
The Gladiolus flower symbolizes strength of character, faithfulness and honor to mankind. The Gladiolus flower has 260 different species. Most of these flowers are native to Africa and 10 are native to Eurasia.
A white daisy or an Azaleas
The September birth flower is the Aster. The meaning is love, faith and wisdom. It symbolizes valor