The answer is gorse. They also call it whin or furze and its Latin name is Ulex europaeus. We saw it all over Skye and the Highlands and Loch Lomond / Trossachs National Park north of Glasgow. It also skirts the Salisbury Crags in Holyrood Park near Arthur’s Seat in Edinburgh. We didn’t see it too much in Glasgow, though.
Gorse on the Isle of Skye.
Click on any photo to see a larger version of that photo.
Take a look at my previous posting of Eilean Donan Castle (see here). That’s gorse in the lower right hand corner. Also immediately to the left of the castle.
Gorse by the roadside as you enter Portree on the Isle of Skye.
Gorse and other vegetation on the road to our B & B just outside the town of Portree on the Isle of Skye.
Gorse on the roadside near a trailer park on the Isle 0f Skye.
According to Wikipedia, ulex is “a genus of flowering plants in the family Fabaceae. The genus comprises about 20 species of thorny evergreen shrubs in the subfamily Faboideae of the pea family Fabaceae.” According to other Internet sources, the flowers are edible and used in salads, teas, wine and beer. The thorns and seeds are not edible, however. The flowers are also sometimes used to make a beautiful yellow dye.
The plant grows very thick and is usually 3 to 6 feet high but can reach the height of nine feet. Unfortunately, it also has gained a nasty reputation for being an invasive plant that smothers native vegetation. There’s a remedy, though, if you really need to get rid of it: plant a tree and wait until the tree shades the gorse. It can’t live in the shade.
Gorse near the Eilean Donan Castle in the western Highlands near the Isle of Skye.
Another view of gorse — from the other side of the Eilean Donan Castle.
Common gorse was introduced in the 19th century to various parts of the world including the western US, Hawaii and New Zealand as an ornamental and it quickly went wild causing all kinds of environmental problems. Other ulex species include ulex galii (western gorse or western furze) and ulex minor (dwarf furze or dwarf gorse). Gorse is often confused with the Scotch broom (cytisus scoparius), another invasive plant found all over the American West.
Gorse, larch, spruce and birch near Loch Laggan northeast of Fort William in the western Highlands.
Gorse on the Salisbury Crags in Edinburgh’s Holyrood Park. That’s the Scottish Parliament building on the right.
But it really is a beauty and it brightens up the hills during the winter and spring months when the heather doesn’t bloom. You won’t see the purple heather blossoms in Scotland until late August. Right now the heather plants are just clumps of brown.
Oh, one more thing: get close to a gorse flower (but watch out for the thorns!) and give it a good sniff and you will smell coconut!
Crow Canyon Journal 
I love whin, as I call it, and have never thought of it as invasive.
Ah, I have lovely memories of hot days and the tropical smell of coconut on the breeze. Gorse is a lovely splash of color on the hills, as long as you don’t get too close to those very long thorns.
You’re right; it does add colour on those dull days. Lovely fotos too.