Today's Guardian Country Diary is about the close link between scent and memory, about the way in which a whiff of a natural odour can transport us back to personal memories of our past.
Years ago, when I was learning to identify plants at school, a teacher made us crush and smell a piece of all the plants that we found, emphasising how important the smell of plant can be in identification. There are many that can be named with your eyes closed, like..........
..... hogweed, for example. Just crush one of the seeds between finger and thumb and those oil glands - the brown stripes on the seed coat - release a pungent, slightly fruity aroma that for me is one of the smells associated with the drift from summer into autumn.
Our sense of smell is quite limited compared with that of many other animals, particularly insects. There is a whole scent landscape that we are unaware of that includes mating pheromones and scents that insects associate with food sources. Their scent perception is concentrated in their antennae and you can see how important these are just by watching a honeybee at work.
If you look closely at this one, exploring a day lily flower, you can see that it's touching the pollen with its antennae before feeding ....
...... and this one, visiting Astrantia flowers, is constantly touching them with its antennae while it feeds.
Scent is an important means of communication in bees. They label flowers that they've visited with secretions of their Nasonov glands and also use scents from the same gland to make other workers aware of food sources.
Scent production in flowers is a complex process too. When we poke our nose into a rose to appreciate its fragrance we are using a very crude instrument compared with an insect antennae. Chemical analysis of rose fragrances reveal subtle but distinct differences between the scent of petals and the scent of the pollen; the former is a general attractant to insects whilst the latter orientates them for the true purpose of the visit, to pollinate the flower, once they have landed.
Insect sensitivity to scent is also far greater than our own, with moths being able to detect the scent of nocturnal flowers like honeysuckle from long distances down-wind.
Our ways of describing subtle differences in scent in the English language are as crude as our sense of smell. When we describe an aroma we tend to use general terms like 'pungent' or 'acrid' or 'sweet' or 'foetid' and then qualify them by adding an analogy to another scent that's commonly experienced by fellow humans - like the scent of a herb, foodstuff or excreta. Our language is seriously limited when it comes to describing, in absolute terms, subtle differences between the scents we can detect. Which is why, I guess, that wine tasters resort to such tortured terminology when they are describing the bouquet of wines and often lapse into incoherence.
To see what I mean, watch this..........
But for something even more amazing in the world of insect olfactory senses, take a look at this post on Africa Gomez's BugBlog which reveals how butterflies detect scents with their legs and feet.
Imagine what life would be like if we could do that .........
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