A Northumberland Alpine Gardener's Diary
This entry: 28 July 2013 by John Richards
French Alps 3. Primulas and Saxifrages. Issue 250.
Well, when I started this diary back in the summer of 2006, I don't suppose I thought I would even get to 100 entries, let alone quarter of a thousand! I have been doing some sums. 250 entries in almost exactly seven years. That means that to get to 1000 at this rate, I shall need to blog for another 21 years, which will make me....., well never mind, but if spared, probably too old to write a weekly diary!! The most important thing is to continue while I still enjoy it and then stop. People are occasionally kind enough to tell me that they enjoy reading it, but I write it only because I enjoy doing it ( very selfishly!), and if others gain a little benefit, thats merely a bonus!
This will be the last contribution in which I discuss some of the plants we saw in the western French Alps between June 25th and July 6th, after which it will be back to the garden. Lots to talk about there, but at least its pouring with rain at the moment after the hottest dryest month since 2006 (coincidentally the start of the diary!).
One of our main targets this year was Primula pedemontana, a plant I grow but had never seen in the wild. It is localised to quite a small area around the French/Italian border in Piedmont (as the name suggests), from Mont Cenis in the south north to the Petit St Bernard. However, it is also found in the northern Apennines (where it was known as P. apennina), and in the far north-west of Spain, where it seems to be little known. It is related to P. hirsuta, but has longer reddish hairs on the leaf margin, and longer flower stalks which exceed the leaves.
We first found it on rocks by the road east to the border at Col D'IIseran, on roadside rocks west of Bonneval, wher it was long over flower. However we had been told that if we drove to the Col de Petit Mont Cenis and then walked up the acidic valley to the north, we should find it, and we did so readily, and in quantity. Here are a few pictures, showing some of the variability.
On to P. marginata. Having visited this species in glorious flower in the Maritime Alps in company with Pam Eveleigh in April 2012, it was curious to see it still in excellent condition more than two months later in the year on all of the passes south of Barcelonette. Here it grows at much higher altitudes than in the Maritimes (certainly up to 2450 m on the Col de Restefond), about 150 km further north, and usually on metamorphic schists rather than on limestone. All these factors may contribute to its much later flowering, as did the tardy season. P. marginata is amongst the most variable of Primulas, as the following pictures show. First a pale variety from the Restefond.
Second one with a marked mealy band on the flower, from the Col de Cayolle.
This too is from the Cayolle.
One of the intriguing things about these sites on metamorphic rocks is that sometimes P. marginata grows alongside P. latifolia, a plant which seems to limit itself to acidic formations. When this happens, it is sometimes possible to find the hybrid between them, P. x crucis. On the Restefond in particular, there were large vigorous cushions of the hybrid which were either over, or which seemed not to have flowered. However we did find one beautiful example in full flower (P. latifolia was completely over at this stage). Notice the very narrow flower tubes compared with P. marginata.
The next photo shows P. marginata (to the bottom left) and P. x crucis mats (top right) on cliffs at the Col de Restefond.
A quick reference to the oxlip, Primula elatior, which was still in flower during the delayed season on all of the Barcelonette passes, and of course the little birds-eye primrose, P. farinosa in wet limy places everywhere.
Together with P. pedemontana, two of my other main targets were the rare and localised saxifrages, S. diapensioides, and S. valdensis. I already showed a picture of the former, but I think it is worth discussing in more detail. This is of course one of the very few Porophyllum section saxifrages in the Alps, and all are localised to limestone cliffs and boulders in limited areas (the others are S. tombaeensis, S. vandelii and S. burseriana). I had already seen the previous three in the Dolomites or the Garda area, and featured them in earlier blogs, but I had never seen S. diapensioides in the wild. Good friends told me that rocks above the Col de Petit Mont Cenis was a good location, but before this we stumbled on a plant on a limestone boulder on the east side of the Col de Galiber where a lady at the Lautaret Botanic Garden told me it was well known.
However, after we had visited P. pedemontana, we stopped at the Col de Petit Mont Cenis and walked up to low limestone cliffs above the road, each side of a track leading south.
The saxifrage grows in several places on this rock, usually embedded within hollows in the vertical face, so that plants receive no water from above.
Now to Saxifraga valdensis. This rather obscure plant is another endemic localised to the French-Italian border, although the Col d'Iseran, a well-known locality, is its northern limit, and it stretches south as far as the Mercantour. It is a silver saxifrage, related to S. cochlearis, but very small and tight. It has no teeth at the edge of the leaf (as does the often confused S. paniculata), but instead the surface of the tiny leaf is covered with pimples formed by lime glands.
A friend advised us of a site on roadside rocks near Bessans, but we could only find S. paniculata there, although some forms were very tiny and superficially resembled S. valdensis closely (as Farrer commented 'there is scarcely a catalogue that does not offer it, or nursery that possesses it') and this is equally true today. I also searched innumerable limestone bouldrers in the vicinity of Bonneval on the road to Iseran, but also without success.
It was only when I came to examine photographs of a strange saxifrage we found growing with S. exarata on rocks above the road on the route up the Restefond, that I realised that we had found S. valdensis there, much further south on one of the Barcelonette passes (this is still in range according to Webb & Gornall). My eye had been caught by Daphne cneorum growing on a roadside cliff, and when I climbed onto the top, I found these two saxifrages growing together. You will see that the S. exarata (bottom left) has three-fingered leaves, but the S. valdensis (top right) has entire leaves which are pimpled all over.
It was interesting how variable the S. paniculata was in the Bonneval area. Many were very tight and congested, and with unbranched, very few-flowered inflorescences, and these are often confused with S. valdensis.
By far the most spectacular silver saxifrage in the area is however S. callosa, which is found in all the limestone gorges which lead from Barcelonette to each of the passes Allos, Cayolle and Restefond.
Two more saxifrages. Amongst the 'mossies', S. exarata is ubiquitous on boulders, seemingly dismissive of rock type, although it may shun the most acidic and sterile of formations. However, S. pedemontana grows both at Casterino, in the Maritimes above the Roya Valley, where it was over flower, and at Mont Cenis. At the latter locality it grows on rocks above the main road, where it looks like a large version of S. exarata, but with longer and much more dissected three-fingered leaves.
Finally, back to the Maritimes, where the strange little S. cuneifolia is common on all the rocks, often growing with Primula marginata.
As this is my last French entry, I am ending with a few star turns which don't fit into any of the categories discussed so far. First, two wonderful plants on the great screes which the road crosses on the route up to the Col de Cayolle in the northern Mercantour. First, Campanula alpestris. This is well known by the Lautaret road too, but I think we were much too early for it there.
At the same site, growing alongside the campanula, and with other goodies such as Daphne cneorum, the superb Viola cenisia, totally unexpected here. We didn't see it at Mont Cenis.
Viola calcarata is such an ever-present in all the sites we visited, abundant and often in a welter of colours (lilac, purple, yellow, white, cream) that it is easily overlooked. But it is a superb plant, possibly at its very best on the Col de Cayolle.
Finally, and also very much a feature of all the sites we visited, (apart from those at the end in the Maritimes) Androsace vitaliana, often known as Vitaliana primuliflora, but proven by the DNA to be an aretian androsace.