Roses and lilies have been found to have a positive effect on both male and female libido.

Work done by Helen Farmer-Knowles, a counsellor on natural remedies and cosmetics and an aromatherapist, points to the beneficial effects of scented flowers - and particularly roses and lilies (as these are the ones that have been investigated) to improve our love life.

Helen Farmer-Knowles tells us: Plants and their flowers have been a part of human culture since Neanderthal times. Plant life has nurtured and sustained us throughout millions of generations. The roots, branches, leaves, flowers and seeds now found in the garden were our food and medicines. Their medicinal properties were important, because the first basic prerequisite of 'good sex' is 'robust health', sexual prowess depends upon it.

But flowers and plants offer much more. They regale the senses of sight, touch, sound and particularly smell. Their colour, form, texture and fragrance have long given mental stimulus to love-making ­ both the thought and the deed - for the romantic and poetic soul.

Flowers, particularly scented ones, can aid sensuality and alleviate stress. The texture of rose petals is sensuous and silken to the touch. Not only are the senses of sight and touch stimulated by the rose, but its fragrance hides a scientific secret that aids 'falling in love'. PEA, phenylethylamine, is a substance found in fresh roses, which helps give them their distinctive scent. PEA contains an amino acid known to slow the breakdown of beta-endorphins. Beta-endorphins are "happy hormones", which give us a high and the euphoria of being in love. PEA is also present in chocolate. A suitor who comes bearing a bunch of red roses and a box of chocolates has long been seen as a romantic. We are just beginning to understand why. The effect of PEA has been described as a mood-altering chemical that is able to prolong feelings of sensuality.

Life's simple pleasures, such as savouring the fragrance of a favourite flower, have a measurable affect upon mood in relation to the immune system. A good mood and good health boost our immunity, and are necessary to well-being and a healthy sex life. Scented association of ideas, scented memories of a past pleasurable incident or event, can also trigger the mental perception into a sexual response.

Some romantics, men or women, may prefer clear scents, such as spring flowers like sweet violets (so dear to French Latin lovers, especially Napoleon and his Josephine), or lily-of-the-valley. Others may have more exotic tastes in natural flower perfumes and respond well to the deep aroma of tuberose, erotic jasmine, or narcotic narcissus.

The lily may be traditionally association with purity and the Virgin Mary ­as the Madonna lily suggests - but lilies have a particularly strong feminine appeal. Perhaps their ancient use as a warming and mollifying scented ointment to treat 'female' complaints, remains in our unconscious collective memory. In modern times the ancient 'Oil of Lilies', that took at least 2,000 stems to make, is no longer within our grasp. However, to lull and relax lovers, a bedside bowl of heavily scented lilies, redolent of the orient can work wonders on sexuality. The scent is very calming, and a relaxed attitude is important to successful sex.

Libido, the intensity of sexual desire, can be increased by floral aids to arousal. For example, tobacco flowers (Nicotiana) or romantic gardenia, with their sensual aromas, a heady hyacinth plant, or a vase of luxurious cut flowers, can help pave the way to sensuous and sensitive 'love-making'.

In our high-tech busy stressful world, the power of flowers, and their sexual appeal to our senses, should never be underestimated or forgotten.