There are a few other flowers considered to be romantic also.
The Romans believed that the daisy was once a wood nymph. One day, while dancing in a field she was seen by Vertumnus, the God of Spring (who fell in love with her of course). But when he reached for her she got frightened. So, out of pity the other gods let her sink into the earth and she became a daisy.
I do not know how the game of holding a daisy and plucking off it's petals saying "He loves me" or "He loves me not" got started.
As far as Violets go....one day it is said that Venus got jealous of a group of beautiful maidens. And when Cpid refused to say that his mother's beauty was better than theirs, Venus go furious, so she beat her rivals (these maidens) until they were blue and she watched them shrink into violets.
In the Science of Botany, the cornflower is known as Kyanus, named after a Greek youth who was born in a field one day, making garlands of the blue blossoms for the altar of Flora, Goddess of Flowers. He died, unfortnately, leaving some of the garlands undone and so this touched Flora's heart and so in his honor she named the flowers after him.
Say It With Flowers...
This is most commonly known as FTD's slogan today. But what to say and with what flower? Here are some traditional meanings for some other flowers often sent for Valentine's Day or other touching moments:
Bleeding Heart = Hopeless, but not heartless.
Gardenia = I love you secretly.
Gladiolus = You pierce my heart.
Lily-of-the-Valley = Let us make up.
Rose - I love you passionately.
Sweet William = You are gallant, suave and perfect.
Violet = I return your love.
Green leaves represented hope in a love affair. (Often rumored to be the reason why British girls sprinkled bay leaves with rose water and put them on their pillows on Valentine's Day Eve. They wanted to see their loved one in their dreams.)
Sweetheart, Sugar Pie, Honey etc.
When people are in love they just seem to automatically develop this type of dialogue. But why? We often refer to someone we care about as sweetheart or honey. Researchers have found that when we fall in love, a chemical called phenylethylamine or phenylalanine is produced.
This drug is responsible for that erratic, psychotic love high that we all feel. When phenylethylamine or phenylalanine is flowing through our veins it's as if we are on amphetamines. We can stay up all night and work all day the next day. And a pheromone called androstenol is also released, which heightens our sexual attractions. Thus, we also end up producing what is called a sweet taste in our mouths and we start spouting off phrases like "luscious" and "sweet" and "honey" and other things that we like such as "muffin" or "cupcake" or"pudding."
However, there is nothing as bad as love gone wrong! And so then we suddenly start spouting off words that have to do with being disgusted, depressed, angry, bitter etc. These are like, "a sour taste in my mouth" or "foul mood" or even being a little "stinker."
Chocolate
Believe it or not, chocolate contains the same chemical mentioned above called phenylethylamine or phenylaline that is produced in our brains when falling in love, and that gives the same emotional high related to amphetamines.
Many psychologist feel that chocolate is an instant "love booster" and an automatic sweet taste in our mouths. And with some people, both chocolate and love can be addictive.
Anyway, the idea of giving chocolate to someone we care about is a way to stir up the same emotions in them (only artificially if they don't really feel the same way emotionally back) as well. As with all drugs, the phenylethylamine will wear off if it's not produced due to real emotions. Some also say that "sweets for my sweet" is a pun for giving any candy to someone you care about.
Love Knots
It has no beginning and no end and consists of graceful loops (sometimes forming hearts) in which messages of love are either attached and knotted in (or written on the ribbon or rope) and read by turning the knot around and around. And, if you couldn't make a real love knot, then many Valentines included a design of one.
A young man often hung this love knot on his true love's doorknob, slipping a letter under also. (Some feel this began with the sailors since many were skilled at making fishnets and so doing knots or macrame were their skill. Others say it is a celtic custom and design. While others say it is Scandinavian.)
Paper Hands
By the 19th Century another symbol of love became the paper hand. It was considered a symbol of courtship because of the custom of a man "asking for a lady's hand" in marriage. And eventually tiny paper gloves became a valentine card symbol as well....evolving into gloves (esp. silk) becoming a popular gift to for a man to give his sweetheart. Eventually, a woman sort of expected a pair of good gloves as a gift (in she was in certain social circles). Eventually (I guess it depended on how well you knew the woman?) a man would also give shoestrings, silk stockings, garters and jewlery to his sweetheart for Valentines.
Valentine Lace
Expensive Valentines today have real lace, perhaps gold charms, real flowers (or dried) and even made with red velvet and not paper. For thousands of years, certain "pretty things" have often been associated with romance. In the days of olde, knights often rode into battle with his lady love's scarf or ribbon tied somewhere on him. Lace, because of it's delicate nature, has come to represent something lovely to look at and thus represent love (because lace really isn't practical as far as a fabric.) So lace as long as 400 years ago because a popular trimming for clothing...especially clothing associated with love = wedding dresses!
How lace paper got made was purely accidental. Joseph Addenbrooke in 1834 was working for a London paper when by accident a file brushed over a sheet of paper embossed with a raised design. The high points of this embossed design thus got filed off leaving small holes, and giving a lacey look to the paper.
This led into the business of making paper laces and soon others followed --- competitively to the point where some of these paper laces are of museum quality today.