Roses are red, violets are blue.
But what if roses were blue?
Florists might stand to make a lot of green.
Modern biochemists and geneticists are now closing in on a prize that has obsessed rose lovers for centuries -- the creation of the true blue rose.
The flower does not exist in nature, and despite centuries of effort, no breeder has managed to even come close. They have called many roses blue -- Blue Girl, Bleu Magenta, Blue Moon.
The only way to create the elusive and unnatural color blue is by manipulating the genetic code of the rose, and millions of dollars are being spent on the effort by genetic engineering companies.
The prize is a hefty piece of the $25-billion global cut flower market, which hasn't seen a major twist in roses since the introduction of yellow around the turn of the 20th century.
But beyond the monetary prospects, flower lovers are already fantasizing about what new emotional dimensions blue would bring to the rose.
"You think of blue as the ocean and sky, which are very powerful elements," said Amulka Kitamura, a designer at the Flower Box in Santa Monica. "I think it would be stunning."
To conjure the elusive color, scientists have plucked genes from blue petunias, fiddled with indigo-producing enzymes from the human liver and delved into the mystery of King George III's occasionally blue urine.
So far, they've made some really nice purples.
Humans have been growing roses for almost as long as civilization itself. The first cultivated varieties appeared in Asia 5,000 years ago, and mention of the flower is woven into tales across the ancient world.
An example is found in ancient Hindu legend. Brahma, the creator of the world, and Vishnu, the protector of the world, argued over which flower was most beautiful -- the lotus or the rose.
Vishnu supported the rose and Brahma the lotus. Brahma had never seen a rose before, but when he did, he immediately recanted and rewarded Vishnu by creating his bride, Lakshmi, from 108 large and 1,008 small rose petals.
Until the beginning of the 19th century, all roses in Europe were shades of pink or white, said Clair Martin, rose curator at the Huntington Botanical Gardens in San Marino.
The first scarlet roses came from China around 1800, he said. Unusual green roses arrived a few decades later.
Bright yellow roses entered the palette around 1900, when Frenchman Joseph Pernet-Ducher, after more than 20 years of breeding roses in a search for a hardy yellow variety, simply stumbled across a mutant yellow flower in a field, Martin said.
"All of our bright orange and yellow roses descend from that single rose," he said.
Painstaking cultivation has revealed all of the remaining colors, except blue. Well, black is missing too, but the commercial possibilities of a black rose are, understandably, smaller.
"I wonder what it is in us that wishes so poignantly for blue roses," said Luanne Wilson, a rose enthusiast in Richmond, Calif. Is it "a desire for the unique, a love of that color or only a twisted yearning to have something nature doesn't provide?"
Frank Cowlishaw, an amateur rose breeder in Derbyshire, England, has spent 25 years trying to tease the color from nature through careful breeding.
His "Rhapsody in Blue" variety is one of the bluest roses that does not rely on genetic tricks for its color.
Chris Warner, a rose breeder in Derby, England who distributes Cowlishaw's roses, said that Rhapsody in Blue was an extraordinary breakthrough. "The ladies love it," he said.
The rose, however, is purple.
"It fades to a lovely slate blue," Warner hastened to add.
The problem is that blue pigment does not exist in roses. No amount of breeding will bring it to life.
"We're trying to attain the apparently unattainable," Cowlishaw said.
Many flower pigments have the same basic chemical structure -- a molecule called an anthocyanin. Extra chemical decorations, called hydroxyl groups, determine the color. One extra hydroxyl group makes a dark brick red, two is a light pinkish red and three is blue.
Roses do not have a gene that allows them to add the third hydroxyl group, which makes the blue pigment delphinidin.
Purple roses, which you might think contain blue pigment, actually get their color from a reaction between a red anthocyanin pigment and other molecules in rose petals. Unfortunately, there is no way nature can get rid of the reddish tinge.
So why not pull a blue gene from, say, a petunia and put it into a rose?
"It's not as simple as taking one gene from one plant and putting it in another," said John Mason, research manager for Florigene, a biotechnology company in Melbourne, Australia.
To begin with, anthocyanin pigments are sensitive to acidity. That's the reason hydrangeas can be blue or pink. Gardeners say that if you want blue hydrangeas, add aluminum sulfate to the soil to make it more acidic. Any blue rose also would have to be modified to increase the acidity in its petals.