ags logo

Saxy silvers – January 2019

January 15, 2019
Content Sidebar

Firstly, belated wishes for a happy and healthy New Year to everyone!

One nice surprise at the start of the year was the arrival of the rejuvenated latest edition of ‘The Saxifrage Magazine’ through the post. This was the most interesting and best-produced issue for many a year. Congratulations to the new Editor, Razvan Chisu, and if I haven’t got all his cedillas and diacritics in place, I am sure he will forgive me. He has done a super job, not least by sponsoring a stellar clutch of articles on a diverse range of topics. How good to see intelligent, informed articles on mossy saxifrages from Paul Kennett, such a Cinderella group, yet to become fashionable and so often misnamed in cultivation.

There is also an interesting article on silver saxifrage hybrids by Adrian Young, who maintains such an important collection of both Porphyrion (‘Kabschia’) and silver (Ligulatae) saxifrages at Waterperry, near Oxford. He describes as a new hybrid binomial S. x  cottianensis, the hybrid between the very rare and localised S. valdensis and the ubiquitous S. paniculata and this got me thinking. The best known colonies of S. valdensis are in the vicinity of Bessans, a village which lies on the road between Lanslebourg, north of Mont Cenis, and the Col d’Iseran. This is mostly limestone country, and around Bonneval there are many huge boulders, several metres high, scattered in flower-filled meadows, full of Paradisea and other delights. Sheila and I spent a idyllic afternoon cruising round these which were full of saxifrages (S. exarataS. paniculata, S. oppositifolia and S. granulata come to mind), but I never convinced myself that I found S. valdensis. However, a few rosettes of the most promising candidates were put in my pocket for later reference with a identification guide.

One of the delights of silver saxifrages is that they are loath to die and root readily, and so I still grow a couple of these in troughs, now grown to a considerable diameter. Adrian shows that whereas S. paniculata has sharp leaf-teeth, the margins of the leaves of S. valdensis is entire, whereas the dwarf hybrid (with really tiny rosettes only about 1 cm in diameter) has shallow blunt teeth. Examination of these two clones convinces me (and, I believe, Adrian) that although we never found S. valdensis there, we did unwittingly collect the hybrid.

Here is the other clone.

In fact we did find Saxifraga valdensis on that trip back in 2013, but on the Col de Restefond, within the known range of S. valdensis, but not to my knowledge a recorded station. Here it grew in the company of S. exarata again on limy banks above the road, in a zone famed for the profusion of good forms of Daphne cneorum. I illustrated this find in issue number 250 and won’t repeat myself. If you want to catch up with old entries and are new to this diary, or perhaps to the new format, scroll down to the bottom of this entry where there is a list of all the previous entries (arrow). Have fun!

The other hybrid given a new binomial by Adrian is S. x hoekiana, the cross between S. callosa and S. paniculata. In fact, this is a frequent cross in cultivation. I thought I had found it together with both parents at Trinita in N. Italy, together with Primula allionii, in 2012. This is S. callosa v. callosa, with very scraggy leaves, and some of the plants were much neater, more like S. paniculata which grew alongside (Diary 213). However, Beryl Bland was very sceptical, and so recently, was Adrian. I also thought I had found this hybrid back in the autumn of 2008 at the well-known location for this cross of Gorges du Verdon. However, I have just re-examined the picture for signs of hairs on the scape. S. callosa (here the much neater v. australis) is normally glabrous, so hairs are a good sign of the hybrid. I found none. Here, nevertheless, is a picture of this good form of S. callosa.

Truly, Saxifraga callosa v. australis can be a magnificent plant. Here it is on the limestone walls of the lower gorges north of the Restefond in 2013.

I don’t find S. callosa the easiest of the species to cultivate. Various forms of S. hostiiS. paniculata and S. crustata are much easier here. However, I do grow one clone of v. australis which has persisted for many years.

In the last few years, a seedling has appeared next to the S. callosa just illustrated, just where the flower spikes sheds seeds. It is not typical of S. callosa and a close examination of the leaf margin leads me to suspect that this has resulted from a cross with S. crustata (there are many plants of S. crustata in the vicinity). Adrian thought it might just be a seedling of S. callosa but I am not so sure. Either way, it is a potentially attractive plant.

Obviously this provides an excuse to illustrate S. crustata in winter. As I say, rather surprisingly in this acidic garden, this limestone speciality from the south-eastern Alps (easterly in its distribution even in the Dolomites) is a good doer here and we have lots of it. The lime crustations in the narrow bluish leaves are indented into the entire leaf margin.

Here, S. crustata has seeded into a mat of Saxifraga continentalis. This is a rather odd little species (Mossy) which disappears totally after flowering for three months of what passes for our summer.

Continuing with the theme of hybrid silver saxifrages, readers of recent issues will recall that this last summer we encountered a stunning mixed population of S. hostii subsp. rhaetica and S. paniculata growing on porphyrite below the Valles Pass (entry 363). It soon became evident that some particularly striking individuals were of the hybrid S. x churchillii, a fairly well-known cross in cultivation. Once again, the few rosettes that were taken to confirm the identification were not discarded, and they have established well. This clone has particularly handsome foliage. It is very similar to illustrations of cultivated forms of this hybrid.

This brings us neatly to S. hostii, a popular species here and a very good doer. In our first Hexham garden, nearly 50 years ago, we found a large silver saxifrage in planters when we arrived and we have grown it ever since. It is a vigorous, sprawling plant, very useful as a ground cover, a form of the eastern subsp. hostii.

We grow several forms of the more compact westerly S. hostii subsp. rhaetica, two of them introduced as single rosette cuttings from the central Italian Alps. It too is a fine plant here. It can resemble S. crustata although with wider and less blue leaves.

Saxifraga cochlearis is famously restricted in the wild to the lower Roya Valley on the French-Italian border. Arguably, it is the most attractive of all the species, with attractive slender hairy red stems and tight cushions. The main form here is the very tight v. minor. Two others, one received as v. major, are probably hybrids. V. minor is a super plant here, easily rooting when dibbed in, but easily swamped by moss if neglected as it is so small and slow.

Here is S. cochlearis growing in the Cairos side valley of the Roya, flowering in May.

In the summer of 2017, we were in the central Italian Alps not far from Pellegrino when we encountered a cliff above a waterfall plastered with the very local S. cotyledon. We have also seen it in the Pyrenees and it grows in Norway too. It no longer grows here (once we grew a good Norwegian form), but we do grow some of the ‘Southside Seedling Group’. Here first is S. cotyledon in Italy.

This is one of our groups of Saxifraga ‘Southside Seedling’, grown vertically in a rock wall.

This is a real trap. Saxifraga mutata can look very like S. cotyledon vegetatively, but its spire of weedy orange flowers shows it to be a relative of the yellow mountain saxifrage, S. aizoides. We find it to be monocarpic but it sets loads of seed and we usually have some groups of seedlings.

Saxifraga paniculata is of course the most familiar and widespread plant and we grow a lot of forms. It is known for its sharply toothed and incurving rosettes. I believe that my favourite is one of many collected originally by Farrer, ‘Minutifolia’.

For some reason the Caucasian S. cartilaginea is still often thought of as a relative of S. paniculata, but it seems very distinct to me. It is slow but persistent here, unlike the other Caucasian, S. kolenatiana which we lost.

The point of this brief survey (and I have shown less than half the silver saxs grown here) is that they are of easy culture and, unlike so many good rock garden plants, they give good value 12 months of the year, being excellent foliage subjects as well as spectacular in flower. They are due a renaissance.

Mid January, and quite mild so far. The earliest snowdrops here, ‘Three Ships’, ‘Straffan’, ‘Dionysus’, G. ikariae, an early ‘Sandersii’ clone, are already starting to flower. Many others are scarcely through the ground. Here is a new one to me, acquired last year, ‘Lady Alice’, an early Plicate. At times ,I think that snowdrop foliage can be as important as the flowers.

Hamamelis mollis. Such a good winter shrub!

Image of John Richards John Richards

John Richards has lived in south Northumberland for 50 years and has been a keen grower of alpines, and visitor to the mountains, throughout the half-century. He and his wife Sheila have been in their present garden 30 years and John has been writing this diary about the garden since 2006.

John is Emeritus Professor of Botany at the University of Newcastle, where his research interests centre on the evolution and genetics of plant breeding systems. He is an authority on the genera Primula and Taraxacum (dandelions!). John is an AGS judge, exhibitor and Vice-President and previous President (2003-6).