Begonia: unrequited love; Beware, I am fanciful
Calla lily: feminine modesty, panache, magnificent beauty
Camellia: excellence, beauty; perfected loveliness, contentment
Crocus: youthful gladness, pleasure of hope
Light-colored: I understand you
Red: I will not economize
White: warm hearted
Daffodil: regard, respect, gracefulness, chivalry
Daisy: innocence, simplicity
Dusty Miller: felicity, delicacy, venerable, industriousness
Fern: fascination, sincerity
Red: comfort, health, protection
Scarlet: comfort, consolation, folly, stupidity; Your smile bewitches me
Johnny-jump-up: happy thoughts
Heather (white): good luck
Hyacinth: kindliness, sport, games
Hyacinth grape: usefulness
Ivy: wedded love, fidelity, constancy, friendship, trustfulness, ambition, tenacity
Jasmine: transport of joy, amiability
Jonquil: I desire a return of affection; Have pity on my passion!
Lavender: devotion, luck, success, happiness, distrust, soothes the trembling and passions of the heart, ardent attachment
Narcissus: egotism, self-love, self-esteem
Orchid: luxury, love, refinement, nobility, scholarship, a belle, beauty, numerous progeny, lust, I await your favors
Cattleya: mature charms, matronly grace, flamboyant
Cymbidium: magnificence, scholarship luxury, love, beauty
Phalaenoppsis/moth: evening joy.
Pansy: thoughts, loving thoughts, You occupy my thoughts.
Ranunculus: Your are rich in attractions, I am dazzled by your charms
Rosemary: remembrance; Your presence revives me; fidelity, devotion, wisdom
Stonecrop/sedum: tranquility; welcome home husband however drunk ye be
Tulip: fame, charity, the perfect lover, consuming love, happy years, memory.
Pink: love, imagination, dreaminess
Red: declaration of ardent love
Variegated: beautiful eyes
White: lost love
Yellow: hopeless love
Of course, there are many more plants that could be used and there are more meanings of all the plants but perhaps this list suggests some possibilities. The best book I found on the subject is Tussie-Mussies: The Language of Flowers by Geraldine Adamich Laufer Workman Publishing Company, 2000. I borrowed it from the public library but you can buy a used copy from Amazon for less than a dollar.