Colour and fragrance in flowers originally served to tempt insect life – and so ensured the survival of the species. But the siren song of the rose has, over the aeons, captured a far wider audience. In a fitting tribute to the species, the image of a fragrant, red rose has become the universal symbol of love.

Throughout the ages, man has sought to capture the tantalisingly elusive perfume of the rose. People seem instinctively to bow to a rose bloom – its beauty is a lure that holds the promise of further delight. One inhales deeply, eyes closed to focus the senses and, if the rose proves to be fragrant, ecstasy ensues!

It is a common belief that modern roses have lost the powerful fragrance of older varieties. In fact, most fragrant old rose varieties are still being grown today. What is more, most modern roses are superior in flowering ability, brightness of colour, shape of flower and firmness of petal.

Some 25 different sorts of rose scents can be identified and some roses have a mixture of these perfumes. Most Hybrid Teas appear to contain seven of the basic scents associated with the genus, or a mixture of them: rose, nasturtium, oris, violet, apple, lemon and clover.

To identify rose perfume:

Begin with a brief sniff, no more than a few seconds long, lest the hypersensitive nasal olfactory cells become anaesthetized. Let your memory go to work. Explore your personal collection of scents for a similar fragrance.

Having analysed the head space, take a deeper sniff and smell the heart and then the base of the rose. (Remember that it takes 12 hours for a rose to play all its notes, and the composition of smells varies during the day.)

On average, people are able to memorise and identify several hundred different smells. Henri Delbard, in ‘A Passion for Roses’, appends colours to scents and allocates a pyramid of colours to each variety. Since scent is generated when alcohol oxidises, temperature plays a major role in the release of perfume. On warm days, fragrance is strongest. During cold spells, fragrant varieties may lose all trace of their perfume; while extreme heat can cause fragrance to escape faster than it is made.

It is futile to pick an immature bud and peel off its petals to establish its scent. In this respect, the rose differs from many other flowers. The oils in a rose can only be synthesized by mature cells at a relatively late stage. Cut roses from florists may have no fragrance as they are often harvested at an immature stage. Blooms picked when the outer petals have fully reflected will exude perfume for days to come at evenly warm room temperature.

The scent comes from tiny cells on the undersides of the petals. As a rule, dark-coloured roses are more strongly scented than those of lighter hue. Cross-pollination, however, is changing the rules, resulting in varieties of strongly scented white roses – and deep-red blooms with hardly any fragrance at all, but most of all for thick petalled, commercially grown florist roses, to exude scent.

To test for fragrance, pick a semi-open bloom and keep it in your pocket or under your hat for half an hour. You will soon know whether it is a fragrant variety or not.

Some categories of scents:

•           citrus

•           aromatics, such as aniseed and lavender

•           flora, such as rose, jasmine and lilac

•           greenery

•           fruit, such as raspberry, pear and peach

•           spices, which include cloves, nutmeg and cinnamon

•           wood and balsam i.e. vanilla and heliotrope at the base.