From the National Encyclopedaedia of Business and Social Forms,
embracing
The Laws of Etiquette and Good Society, etc. etc. (the title goes on for a full page!)

Published in 1884, the following was taken from the Language and Sentiment of Flowers

pink: boldness
violet, blue: faithfulness
violet, Dame: watchfulness
violet, sweet: modesty
violet, yellow: I cling to you both in sunshine and shade

There are a bunch of specifics for different types and colours of roses, but a red rosebud stands for pure and lovely

kat