A June trip to the Serra d’Arga mountain region in northern Portugal, just south of the border with Spain, reminded me of one of the many pearls of wisdom to be found in Catherine Stewart’s blog postings for GardenDrum. The one I have in mind was about the importance of pH (point number 3 in The 7 best pieces of garden advice I’ve had): “Other than drainage, it [pH] is usually the reason as to why something is not thriving”. The flip side of that, of course, is that pH may also be the reason why something is thriving.
Although the temperature, and the occasional olive grove or small field of grape vines, convinced us that we were definitely in southern Europe, the terrain and vegetation of the Serra d’Arga are in many ways remarkably like parts of Scotland. A quick look at a geological map of Europe shows the most likely explanation: the predominant feature of both western Scotland and the north-western part of the Iberian peninsula is tertiary volcanic rocks, creating acid soils and a very different landscape and flora from, for example, the limestone mountains of Italy featured so beautifully in Helen McKerral’s blog postings from the Dolomites a couple of years ago.
Our walks in the Serra d’Arga, now largely protected by national park status, were often through high, open heathland punctuated by stands of pine trees and rocky outcrops softened by clumps of heather, gorse and broom. We even came across large lumps of quartzite just like the ones so lovingly used as “features” by some former owner of our garden ( The Mystery of the White Rocks), and on one walk we crossed (with some difficulty) a high, boggy plateau for all the world like the treacherous boggy hills of Argyll.
In more sheltered woodland areas we found foxgloves, ferns, mosses and sedges. Even parts of the man-made environment looked familiar, with dry-stone walls surrounding the fields, and systems of open drainage channels to control the flow of water – though they apparently don’t have our problem with deer, as kitchen gardens stocked with brassicas and beans were completely unmolested.
We were in Portugal in early June, and wildflowers sprinkled the grassy verges and nestled in crevices in stone walls. Without a field guide to the flora of the area – and I haven’t been able to find much on the Web – I was not able to identify many of them, though some appeared to be close cousins of British wildflowers such as Scabious and saxifrage.
One characteristic of the vegetation of large tracts of western Britain that seemed to be completely absent from the Serra d’Arga region was Rhododendron ponticum. This turns out to be more surprising than it seems at first thought, as apparently R. ponticum, introduced into Britain in the 18th century as a garden plant but now an invasive pest, doesn’t come from the Himalayas like many garden rhododendrons but is in fact a hybrid originating from species native to the Iberian peninsula. Presumably, in its native habitat, ponticum or its wild ancestors are much better behaved.