FOR those traversing one of Scotland's highest and most exposed roads, it has become a beloved landmark: a lone rowan that grows inexplicably atop a craggy boulder on the rain-strewn and wind-lashed expanse of Rannoch Moor.

This small, solitary tree can be seen on the left-hand side of the A82, around five miles north of Bridge of Orchy, as the road climbs above the Loch Tulla Viewpoint heading towards Glen Coe.

The roots of the hardy specimen cling to a giant, lichen-covered rock, drawing support and nourishment from the shallowest of cracks. Battered by the elements, the weathered leaves and branches at its crown are testament to the robustness of nature.

How the indefatigable little tree, known as the "Rannoch Rowan", came to grow here has long been a source of fascination. The most likely explanation is a passing bird dropped a rowan berry and the seed – against the odds – managed to land in exactly the right spot to take root within the boulder.

READ MORE: A magical architectural gem reached through a fairy trail

Experts believe its enduring survival is largely due to a lofty perch elevated beyond the reach of ravenous sheep and deer.

The rowan is a tree species that has powerful symbolism in Scotland. According to folklore, planting one near a gate or front door brings good luck and will keep evil spirits at bay. By the same token, it is considered bad luck to cut down a rowan.

Rowans growing out of an inaccessible cleft in a rock – such as the one on Rannoch Moor – or those found sprouting from the crevices of another tree, are said to possess even more potent magical powers. These are known as "flying rowan".

As autumn nears, the nation's rowan trees are laden with plump red berries. One oft-cited old wives' tale is that if the berries are in plentiful supply then it portends a hard winter. However, in reality, the quantity of the fruit owes more to a good growing season than predicting what lies ahead.

READ MORE: 13 unusual and quirky places to holiday in Scotland

Each September, the Rannoch Rowan produces a harvest of berries that belies its inhospitable environment. Strong, steadfast and tenacious: it is a survivor.

What to read: WH Murray, who penned the classic guides Mountaineering in Scotland (1947) and Undiscovered Scotland (1951), has written about the rowan in his books.

What to watch: Grand Tours of Scotland presenter Paul Murton also speaks fondly about this tree, returning to film it for TV programmes several times over the years.