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Bulletin of the American Rock Garden Society Volume 49 Number 4 Fall 1991 Cover: Cirsium acaule Watercolor by Vickie Danielsen of Englewood, Colorado Bulletin of the American Rock Garden Society Volume 49 Number 4 Fall 1991 Features Silver Saxifrages, by Rex Murfitt 243 American Sedums in Czechoslovakia, by Vaclav Plestil 249 Hormones for Fast Germination, by Bob Stewart and Brigitta Presley 253 Interesting Plants of Mt. Olympus, by Josef Halda 261 Gardening in Pine Duff, by Jeanie Vesall 265 Prickly Charmers, by Panayoti Kelaidis 271 Chowder Ridge, An Alpine Showcase, by Ronald J. Taylor 285 Tools I Have Loved, Lost, and Thrown Away, by Sandy Snyder 291 Jovibarbas, I Presume, by Karen Matthews 295 In and Around the Black Hills, by James H. Locklear 297 Departments Awards 305 Saxifraga cochlearis 'Minor' 242 Bulletin of the American Rock Garden Society Vol. 49(4) Silver Saxifrages by Rex Murfitt I grow a dozen or so varieties of leathery with usually conspicuous silvery silver saxifrages grouped around some incrustation. The concentration and trough gardens. It is a pleasant planting arrangement of tiny beads of calcium of mixed sizes, some plants forming carbonate along the leaf margins large, spreading clumps and others enhance the underlying leaf color, miniature carpets. Several plants have giving the whole plant a silvery look. bold rosettes as much as 3" across This group may also be called incrusted while others produce masses of small saxifrages. rosettes less than half an inch in width. Why should we grow these Together these plants make an interest• saxifrages? Why do they have such ing pattern, a lovely combination of appeal to gardeners? Without much shades of green and gray highlighted by doubt it is the silver color that first a few golden clumps. Most of this large attracts us. The intriguing makeup of group of silver saxifrages are represen• the individual rosettes and above all the tatives of a few species, and include symmetrical regularity appeal to some geographic forms, varieties, and natural love of neatness and form found within and man-made hybrids. rock gardeners. Furthermore, there is a The definitive definition of the group wide variety of leaf shape and size, lies in its botanical classification within from short and broad to long and the genus Saxifraga. In 1916 the narrow, and some leaves curve inward, species were described under the while others curve gracefully outward. section Euaizoonia—a Latin word This group offers a great range of which means everliving. Now the plants that will add variety and interest section that includes all the species to the garden. Their symmetry and discussed here is called Section Ligu- quiet beauty fit into any scheme, latae Haworth (Section Aizoonia whether large or small. About mid-May, Tausch). The plants are described as almost as a bonus, flower spikes begin forming leaf rosettes, usually so crowd• to elongate from the center of the ed together that they form cushions or mature rosettes, arching out into pani• thick mats. The leaves are fleshy or cles of chalk-white flowers often carried 243 on mahogany-red stems. One variety the leaves. Neither is true. Many lovely offers rose-red flowers, another delicate species originate from mountain ranges pink, a couple more lovely yellow flow• that are anything but limestone. Take ers. Most species have flower stems in Saxifraga cotyledon, for example. It the 6-12" range although some species comes from lime-free mountains, and have spikes to 2' tall. some writers say that lime must not be Silver saxifrages are not the easiest used near it. The presence of some plants to grow in all garden climates. I lime in the soil will not kill it, but do not am always dismayed when I hear them go out of your way to add extra. referred to as "lovely succulents." The The only species that does totally leaves are rosulate and somewhat dislike lime in any form is the rare S. fleshy, but that is as far as the resem• florulenta, which grows in cool shade blance to sedums, sempervivums, and in the Maritime Alps. It is in its own dudleyas goes. Whatever you do, get rid separate subsection of the incrusted of any ideas that they respond well to saxifrages, the Florulentae. This species droughty, sunny growing conditions. is by no means silver and lacks any They demand far more skill and care incrustation on its regularly arranged than the average succulent. Even in leaves. Reginald Farrer called this the favored Victoria, we have to disregard "Ancient King" and goes on to write some of the cultural advice to be found one of his glowing passages about it. in European books, particularly where Photographs of the large, flat, dark they recommend sunny, dry banks and green rosettes can be found in older crevices. When grown under these books and in the journals of the Alpine conditions, even with several inches of Garden Society. If ever you should have prepared soil, the long, hot, sunny days the opportunity to get a little seed, grab of midsummer on our continent will it. You can have several years of chal• damage them. Try to find spots where lenge and fun trying to produce the there will be some relief for at least half large, 6"-wide, monocarpic rosettes. the day. A place that gets relatively cool Looking through catalogs and books morning sun is ideal. Prepare the spot that mention silver saxifrages, one is with a good 6" of gritty soil enriched soon inundated with lists of names, but with a generous amount of leafmold to a large extent that is all they and peatmoss, and after planting top are—tantalizing names on paper. When dress with a few inches of stone chips samples of listed varieties from several to help keep the soil cool and moist. sources are grown side by side, it is Often summer produces more stress readily seen that many display such for these plants than any other season. minute differences that they hardly Where I have a plant happily settled warrant separate names. Furthermore, and growing attractively into its place in should you order one specific named the rock garden, rather than move it variety from several suppliers, chances and spoil its potential, I resort to shad• are you will receive as many totally ing with a screen of twigs, enough to different plants. This may not be all give some shade during the hottest bad, providing you can identify what spells of summer. you have received. There is a belief that silver saxifrages All is not totally lost among this demand copious quantities of lime welter of names, as some order can be added to the soil for successful cultiva• brought with a little study of the species tion. I have heard it said also that lime and varieties described under the will enhance the silver incrustation of Section Ligulatae. Many of our plants 244 Bulletin of the American Rock Garden Society Vol. 49(4) are from four species, Saxifraga panic- south and central Europe. Many of its ulata (S.aizoon), S. callosa (S. lingula- forms have been grown for many years ta), S. cochlearis, and S. cotyledon. and are still worth growing today. The There have been many changes in size of different kinds will vary enor• nomenclature in this group in recent mously from minute, silvery carpets to years; in older books look for the names bold domes. Generally the leaves are here given in parentheses. Each of heavily serrated and incrusted. In some these four species has features that will forms, the leaves curve inward, produc• help in recognizing their differences. ing an attractive, globular-shaped Varieties and forms of S. cochlearis rosette. There is a range of greens have no marginal teeth along their through silvers and even a couple of beautiful silvery leaves. Closer examina• quite golden ones. The most consistent tion will show that these leaves also feature is the relatively inferior flower expand at the tip and curl back, so they color, from off-white to creamy yellow. remind one of tiny spoons. The flowers It is only fair to acknowledge that these are chalk-white and borne on light, hues blend well with the pure white of arching stems of mahogany-red. other species, setting them off to great I think Saxifraga callosa and its effect. This is true also of the red-spot• forms embody the very essence of ted, pink flowers of S. paniculata incrusted saxifrage beauty. It forms 'Rosea' and the pale yellow ones of S. spidery rosettes, irregular in outline, to paniculata 'Lutea'. Both are worth 2" across. The leaves are long and having and easily recognized at flower• narrow, blue-green, and richly incrust• ing time. ed. They are toothless along the I've mentioned the Ancient King, margins and become spathulate at the and here is a good place to pay tips. Younger leaves growing up homage to the most distinct Queen of through the mature ones give an Saxifrages, S. longifolia. There is a bit uneven appearance that is very attrac• of confusion between the true species tive. This species will have pure white and a hybrid called S. 'Tumbling flowers carried in gracefully arching Waters'. Both are well worth growing plumes, at least 12", sometimes nearly and take several years to grow to the 16". It cries out to be planted on cliff• enormous silver rosettes we see like rocks. In the late 1940s several pictured. This is good, because we have forms and superior selected forms were a few years to enjoy them before they available, and what a joy they were.