Why roses produce scents and why some stopped

By Elliot

You’re walking down a platform in Gardens by the Bay when you pass by a group of flowers. The diverse spread of roses and violets catches your eye as the pretty visuals alone was enough to draw you in. As you enter the flower zone, the heavenly fragrance of flora fills your nose. You lean toward a rose and hold it up to your nose, anticipating a strong heady aroma to rush in, and it didn’t disappoint.

Why do roses create scents?

There’s a reason why roses create perfumes, and no — its not for us humans to sniff, but they’re for insects and animals. The scent acts as a lighthouse, guiding pollinators — bees and butterflies in the day, and moth and bats at night — to a particular flower whose nectar and/or pollen is the reward. With every successful pollen transfer, sexual reproduction is ensured, continuing the line of its species.

If you’re looking for more technical terms, a study into the chemistry of roses has discovered the enzyme responsible for the sweet fragrance of roses, RhNUDX1. The enzyme works in the cells of flower petals and is used to create a substance called monoterpene geraniol, the primary ingredient in rose oil.

The next day, you’re walking down the street when you see a florist. You walk into the shop and you bend down, placing your snout near a new stalk of white roses, excited to learn a new scent of mother nature — this time, nothing. You instinctively touch the petals, half expecting the rose to feel of plastic, but its rubbery, it’s definitely real.

So wait, why did some of them stop producing smell?

‘The rose looks fair, but fairer we it deem
For that sweet odour which doth in it live’
– Shakespeare

This quote did not age well in this era of increasingly unscented roses, with 20% of all roses lacking the sweet odour. The reasons for the demotion of scent in roses are caused by our two antagonists — China rose, and Tea rose. A study published in Nature Genetics reported that these two roses, both originating from China in the 19th century were bred with other species to obtain a more diverse variety of flowers and colours like pink, yellow and white.

In addition to diversity, flowers have also been blended with the China rose and Tea rose to better suit different climates, resistant to disease to varying degrees, have higher frequency blooms that last longer when cut or have longer stems for display.

This is extremely important in the mainstream floral industry due to flowers and plants being shipped in long plane rides across the globe with many parts of the world having different atmospheric conditions. Having customers with higher demands also contribute to the need for some of these characteristics.

But everything comes with a price, and the price the roses had to pay was its soul, its scent. Through the many hybridisations, it is believed the enzyme RhNUDX1 responsible for the rose’s smell may have been lost in translation. As such, it is often common to encounter commercial cut roses without any fragrance. This change in the cut rose industry could have led to a change in perception of rose scents, that they are often faint, and non-existent.

Can we return their scent? How?

Fortunately, there is still a group of garden rose breeders who believe in the importance of scented roses in the floral industry, such as the families of David Austin and Meilland. These garden roses require more stringent conditions and care to grow than the unscented commercial roses. Only a small group of growers in the world are dedicated to grow them for international distribution, such as Tambuzi Farm from Kenya who specialises in the production of traditional scented garden roses. With their efforts, we hope the forgotten scents of roses can return, and just maybe, make William Shakespeare proud.