Ten minutes from Tarhill Farm, the road gives way to track, and the track gives way to open moorland. The walk up to Glenlomond begins with a fringe of pine trees before the trees thin and disappear, and the Lomond Hills open out on either side: Bishop's Hill on the right and West Lomond on the left. From here to Knox's pulpit, the path rises through heather. It lines the trail in both directions, stretching into the valley that flows beneath West Lomond, a sea of purple in late summer, and brown and wiry in the winter. The farm and the silver of Loch Leven is visible behind you as you climb.
It is one of the defining images of Scotland. Yet, if you stop on that path and breathe in deliberately, seeking the smell that the image promises, you will be left wanting.
We have looked into this and hope we can clear up the mystery.
https://www.alltrails.com/en-gb/trail/scotland/fife/john-knox-pulpit
What does the chemistry actually tell us?
Calluna vulgaris - common heather - does produce volatile organic compounds. Scientific analysis using gas chromatography has identified more than thirty of them in heather's headspace, that being the airspace immediately surrounding the plant. They are organised into several chemical classes: fatty acid derivatives, monoterpenes, sesquiterpenes, and a small group of alcohols and aldehydes.
The monoterpenes are the most recognisable to a trained nose. α-pinene - the sharp, resinous backbone of Scots pine - is present. So is β-pinene, limonene (clean, and citrus-like), linalool (herbaceous and lavender-like), and β-myrcene (warm and slightly green). These are not rare compounds. They are some of the most widely used molecules in perfumery. If you could somehow concentrate heather's output and smell it in isolation in a laboratory, you would find something recognisable: faintly floral, lightly resinous, with a clean herbal thread.
The sesquiterpenes add some depth to the cocktail: β-caryophyllene brings a dry, faintly spiced woodiness. Germacrene D is green and earthy. There is even 1-octen-3-ol in the mix - a compound more associated with woodland fungi, giving a faintly mushroomy, forest character.
The problem is volume. Heather emits these compounds at concentrations that are meaningful in an enclosed laboratory but vanish almost instantly in open air. The moment wind moves across the moor - which in the Lomond Hills is more or less always - the scent dissipates before it reaches any human nose.
There is also a species question. Calluna vulgaris, the dominant heather of Scottish uplands, is botanically distinct from the bell heathers - Erica cinerea and Erica tetralix - that sometimes grow alongside it. The Erica species are a little more aromatic, but Calluna is the one carpeting the hillsides, and its scent profile in the open air is essentially undetectable.
And yet, everyone who has walked a Scottish moor returns with a sense memory of it. The smell is real. It is just not coming from the heather.
https://pmc.ncbi.nlm.nih.gov/articles/PMC7076469/
What the moor is actually made of, olfactorily speaking
Continuing on our walk up the Glenlomond valley, where the path narrows and the cloud tends to gather, the air changes. A small stream runs close to the rock beneath Knox Pulpit. When the valley top is misty - as it often is, with cloud sitting low over the hills while the farm is still in sun below - you are walking through the conditions that release one of the most potent olfactory compounds in nature: Geosmin.
Geosmin is a bicyclic alcohol produced by bacteria in the soil - primarily Streptomyces species - as they break down organic matter in the peat. Its name comes from the Greek: ge, earth; osme, smell. It is the compound responsible for the scent of rain on dry ground, a phenomenon named petrichor. And the human nose is extraordinarily sensitive to it: we can detect geosmin at concentrations as low as five parts per trillion - more sensitive than a shark detecting blood in water.
When moisture hits peaty moorland soil - when rain falls, or mist descends, or a stream disturbs the ground - geosmin lifts into the air. It is the smell of the ancient organic matter (the soil) that has been accumulating decomposed vegetation for thousands of years. On a wet March morning on Glenlomond, it is everywhere. It is usually what people mean when they say the moor has a smell.
Then there is the air itself. Scottish upland air carries cold and moisture even on dry days, and that absence of warmth changes how we perceive what little scent is present. Smell is partly a function of volatility - warmth drives molecules off surfaces and towards the nose. In cool, moving air, everything is dialled down. The few molecules heather does release disperse faster. What you may notice instead is the quality of the air: clean, slightly mineral, the faint pine resin from the trees at the bottom of the trail still lingering at the base of your sense memory.
In the hollow just beneath the rock, where the wind briefly drops, something changes. Without constant dispersal, the accumulated scent of the moorland - geosmin from the soil, the faint green-resinous signature of heather and grass, the cold mineral quality of the stream nearby - becomes briefly perceptible as a whole. It is not floral or sweet, but rather earthy and clean.
https://www.compoundchem.com/2014/05/14/thesmellofrain/
https://en.wikipedia.org/wiki/Geosmin
https://chem.hbcse.tifr.res.in/wp-content/uploads/2024/08/Geosmin-English.pdf
Burns saw it. He didn't smell it.
Robert Burns catalogued the Scottish natural world with more precision than almost any writer before or since. In 'Composed in August', he records the westlin winds, the blooming heather, the moon rising bright - placing the poet in landscape, using specific observation to open into psychological reflection. The poem is full of sensory detail, but the heather, as it always does in Burns, appears as colour and visual presence.
He does not describe how it smells. Not once, in all of his nature writing, does Burns attribute an odour to heather itself. He was accurate. What he wrote about, olfactorily, was the landscape around it: rain on soil, turned earth, the scent of rivers and meadows and night air. The heather was what he saw, but the smell came from underneath it.
This is a significant, and often overlooked, distinction. The romantic mythology of Scotland has collapsed the visual and the olfactory into a single sensation: heather, and by implication the purple moorland, must smell of something. It must carry the scent of the place. But the most attentive reader of that landscape, Burns, a man who spent most of his life working in it, never made that claim.
https://www.gla.ac.uk/media/Media_1209435_smxx.pdf
What perfumers do instead
There is a version of heather in perfumery. It is described - when the fragrance industry characterises Calluna vulgaris as an ingredient - as a sweet and aromatic honey floral. Not the plant in open air, but the plant's concentrated chemical signature: the linalool and linalyl acetate threading through it, the honey quality from compounds shared with the nectar the plant produces for bees, the warmth that volatility and concentration can restore to something that disperses in the wild.
This is, in a sense, what perfumery always does with landscape: you cannot bottle a hillside. What you can do is find the molecules that carry the character of that hillside - the warmth, the sweetness, the particular quality of its light and season - and work with those.
In Cherish the Bee, we describe this as a Honeyed Highland Floral. The name holds two places at once: the heather moorland of the Lomond Hills and the wildflower meadow at Tarhill Farm itself, where the bees actually work. The honey character in the perfume comes from both - the moorland above, and the meadow below.
It is, in its way, a more honest story than a heather soliflore (soliflore = single-note perfume) would be.
The view back down to the farm
From near Knox Pulpit, on a clear day, you can see across the valley to Loch Leven and the farm below. The heather is all around you, doing what it does best: providing cover for ground nesting birds, nectar for bees, colour for a landscape that would look stripped without it. In flower, in August, it is purple to the horizon. In November, bare and dark, it forms the texture of the hill itself.
What you smell, if the wind drops and the mist is in, is Scotland: the deep geosmin of the soil, cold mineral air, the memory of rain. But, I'm afraid to say, not the heather. Rather, the earth the heather grows from.
This is not a disappointment. It is, if anything, a more interesting answer. The plant that represents Scotland more than any other is, in terms of scent, almost entirely absent from the experience of the Scottish landscape. The smell is elsewhere - in the soil, the sky, the moisture, the ancient organic matter underfoot. Scotland smells of its depth, not its surface.
Heather just shows you where to look.
