Saxifraga Cæsia
Silver Moss, or Grey Saxifrage; Nat. Ord. Saxifragaceæ.
One of the alpine gems. This has been grown in English gardens since 1752, yet good specimens are rarely met with, though its culture is simple and easy. It is found wild on the Alps of Switzerland, Austria, and the Pyrenees. To the lover of the minute forms of genuine alpine plants, this will be a treasure; it is very distinct in form, habit, and colour. Its tiny rosettes of encrusted leaves can scarcely be said to rise from the ground, and the common name, “silver moss,” which it is often called by, most fittingly applies; but perhaps its colour is the main feature of notice. The meaning of its specific name is grey, to which it certainly answers; but so peculiar is the greyness that a more definite description may be useful, in giving which I will quote that of Decandolle and Sprengle: “The lavender-blue is a pale blue (cæsius); it is mixed with a little grey.” This exactly answers to the colour of the pretty Saxifrage under notice, and it is far from a common one in foliage.
The flowers differ but slightly from those of other encrusted forms of the genus, but they are a creamy white, arranged in small panicles on short and slender stems. They are sparingly produced in May and June. The leaves are ¼in. long, aggregate or in miniature rosettes; in shape, linear-oblong, recurved, and keeled. The upper surface is concave, having marginal dots, evenly disposed; the dots are bright and excavated, and some of the leaves (those of the stems) are scale formed. The glaucous or lavender-blue colour is beautifully enlivened with the crystal dots. Its habit reminds one of the more distinct forms of lichens, and, when it is grown with suitable companions on rockwork, it has a happy way of showing and adapting itself in such situation; besides, its colour then shows with more effect.
There is a variety of this species not yet in general cultivation, and it cannot be too strongly recommended to lovers of the finest forms of rock or alpine plants. It is called S. c. major (see Fig. 82). The name at once suggests the main difference from the type, but there are other features quite as marked as that of its extra size in all its parts; the foliage is more crowded, which seems to cause the largest leaves to become more erect, and the habit, too, perhaps from the same cause, is ball shaped; the small rosettes of thick encrusted leaves, from the manner in which they are packed together, form a rigid mass, which differs widely both in detail and effect from any other Saxifrage I know.
These dwarf subjects are best suited for rockwork; but another plan, now much practised, is to grow them in pots. This in no way implies that protection is given or needed—these sturdy subjects are far better fully exposed—but the pot system has advantages; when so planted, the roots are more likely to be placed in a better selected compost, and the specimens can be raised in order to examine their miniature beauties. The above kinds enjoy a gritty vegetable soil; perfect drainage is indispensable. These are not among the Saxifrages that are readily propagated; a few crowns or rosettes with short pieces of stem are not sure to root, and if more careful division is not carried out, perhaps but two or three growing bits from a large specimen may be the result, so lessening instead of increasing the stock. Before cutting let the roots be washed clear of soil, trace the long roots, and so cut up the plant that each division will have a share of them. Sometimes a rather large specimen will have but few of such roots, in which case it will prove the better and safer plan to make only a corresponding number of divisions, so making sure of each. A further help to such newly planted stock is gained by placing small stones about the collars; this keeps the plants moist and cool during the dry season, when (after flowering) the divisions should be made.
Flowering period, May and June.