Where in a flower does the smell come from?

Have you ever noticed how a garden full of flowers smells particularly fragrant on a warm day? This floral aroma comes from oils that are found in the flowers’ petals; these oils readily evaporate when the weather is warm. And it’s when the oils evaporate (when they turn into a vapour) that we end up inhaling them – at which point our noses can detect their scent: we smell them.

(The same principle applies to the ‘essential oils’ that some people heat over a tea-light to relax: as the essential oil – lavender perhaps – is heated, it starts to evaporate, filling the room with a calming lavender scent.)

Each flower produces its own unique cocktail of oils – the chemical equivalent of a fingerprint. The scent of some flowers may be the result of a mix of as few as seven different oils; others are a heady mix of over 100.Flower macro by @Doug88888, on Flickr

But these scents don’t just happen to give us something aromatic to sniff: their primary purpose is to attract creatures such as insects to the flower. By attracting these pollinators to the flower, there’s a better chance of the flower’s pollen being gathered and then being transferred – an essential part of the reproductive cycle of a flowering plant. Without this transfer, the plant would fail to reproduce.

Plants aren’t the only organisms that exploit scent for sexual purposes. We all know what liberal doses of perfume and aftershave can do for the human mating ritual!

Answered by Jon Crowe

Question from Becky Cutlan-Wilson via website

Article by Jon Crowe

August 30, 2013

Jon Crowe is a science publisher (by day) and science writer (at various other times). A biochemistry graduate (University of Warwick, 1997), he was a runner-up in the 2001 Daily Telegraph/BASF Young Science Writer Competition (back when he was still classed as being young). Jon has co-authored two editions of Chemistry for the Biosciences, which first published in 2006, and is currently embroiled in writing the third. He lives with his fiancee, Katy, and their slightly rotund cat, Basil, in Eynsham, Oxfordshire (the location of one of the two toll bridges across the River Thames). They mostly enjoy drinking tea and eating cake. You can follow him on Twitter @crowe_jon

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