Trees and Shrubs for English Gardens

by E. T. Cook

(In the left lower corner, Cistus hirsutus; middle, Rosa alba; to right, R. rugosa Mme. Georges Bruant.)]

Some of the small-growing Conifers, from their compact habit and distinct character, are especially well fitted to break the outline and to give contrast. We think of Pines and Spruce Firs and Cedars as majestic trees, and it is only when one comes to study them in their manifold varieties that we find how many of these range from a height of only a few inches to 3 feet, or at most to 4 feet.

Some species, it is true, do not lend themselves gracefully to the dwarfing process, becoming clumpy and inelegant, but this charge cannot be brought against many of the Cypresses and Junipers. Several of the smaller Conifers, besides, give the advantage of distinct variations of colour with the changing seasons. Reference is not now made to the golden and silver forms, so-called, which occur in most of the genera, and put on their brightest tints in spring, but to the deeper winter colouring assumed, e.g. by the interesting Retinospora ericoides, which alters its summer tone of dark green to purple brown on the approach of cold weather; or by Cryptomeria elegans, a little less hardy, which changes to a fine shade of bronzy crimson. Like other plants, Conifers differ greatly as to constitution, and judgment must be used in their choice. The dwarf alpine form of the Common Juniper (Juniperus communis nana) is very hardy and slow-growing, never becoming too rampant for the smallest Rock Garden, and shares the blue-grey tint which is so characteristic of this beautiful species. J. c. alpina aurea is a delightful small-growing Conifer. In summer the foliage is light yellow, and in winter heavily shaded with bronzy yellow. Very distinct from it is the lovely prostrate Savin (J. Sabina procumbens), one of the best of evergreen shrubs for the Rock Garden, and one most restful and satisfying to the eye at all times in its deep tones of sea green. A first-rate variety is J. S. tamariscifolia, which is of very spreading growth.

DWARF SHRUBS ON ROCK GARDEN.

Cupressus pisifera, almost plumose in one of its many variations, and C. obtusa, both better known perhaps under the garden name of Retinosporas, are admirable, and may be used either in the normal or the dwarf forms according to the greater or less space at command. Almost the last tree, probably, which one would expect to see draping the vertical face of a rock is the Spruce Fir, yet a weeping variety (Picea excelsa pendula) is exceedingly effective in such a position as a foil to hanging masses of richly-coloured Aubrietias or Golden Alyssum, while it looks well at all seasons. Mention may here be made of a remarkable Conifer, Cunninghamia sinensis, of great beauty and very distinct character, which takes the shape, in our climate, of a spreading bush, though in its native habitat it grows into a tree of noble dimensions. It is suitable only for a Rock Garden of some boldness of construction, and in gardens favoured with a mild climate and a sheltered position, but under such happy circumstances a place should certainly be found for this handsome and little-known China Fir.

Another uncommon coniferous shrub, also very distinct and more generally useful than the last, is Podocarpus alpina. Though a native of Tasmania, it grows at high elevations, and is able to resist severe frost. Dark green in foliage, only about 2 feet in height, and of a somewhat spreading nature, it is never out of place in the Rock Garden, whether large or small.

From Conifers we may pass to Veronicas, certain of which might almost be mistaken for some minute form of Cypress. Of this character is a small group known in New Zealand, the natural habitat of a large number of shrubby species, by the apposite name of Whipcord Veronicas. Being themselves alpine, they are particularly well suited for grouping with low-growing mountain plants. Six species or varieties of this interesting section grow naturally at elevations ranging from 7000 to 4000 feet, and are much more hardy than is generally supposed. These are: V. cupressoides, V. c. var. variabilis, V. lycopodioides, V. Armstrongii, V. Hectori, V. loganioides.

The form of V. cupressoides, known as variabilis, was mistaken, on its first introduction, for a distinct species, V. salicornoides, and may still be met with under that name. The small violet or white flowers of these miniature evergreen shrubs are not perhaps much to be taken into account, but they have a distinct value of their own as rock-work greenery. There are other dwarf New Zealand Veronicas of a leafy character, differing essentially from these mimetic species, such as V. carnosula and V. pinguifolia, also inhabiting regions 5000 feet above the sea-level, which are suited for localities with average advantages of climate. Others again, such as V. Lyallii, V. glauco-cærulea, and V. hulkeana, though they grow naturally at lower altitudes, and must be reckoned only half-hardy, may yet be serviceable for Rock Gardens on the southern sea-board, or on the west coast of Scotland. Belonging to the larger-growing and more familiar species of Shrubby Veronica, mention may be made of a good purple-flowered hybrid, of very compact growth, known as Purple Queen, which is exceedingly ornamental from its free-flowering habit. Many of the losses sustained amongst these interesting New Zealand shrubs are owing to drought rather than to frost, and their extreme susceptibility to dryness at the root is a fact not recognised as it should be.

Hardy Heaths are of the utmost value in the Rock Garden, and range in height from the 6 feet or more of Erica arborea to the 6 inches of the well-known E. carnea, and can be used in rough places, where more delicate plants might not thrive. A sudden emergency once arose in the experience of the writer, when a shelving mass of earth had to be shored-up as quickly as possible with such material as lay ready to hand at the moment. This happened to be found in a heap of ugly, yellowish, water-worn boulders of great size, which abound in that particular locality, at no great distance below the ground-level, and must be dug out when any deep trenching has to be done. There was no time to be wasted in facing the stones, which would have made them more sightly, and they had to be used as they were. Fortunately a large consignment of the best hardy Heaths had lately arrived from the Darley Dale Nurseries, and were immediately seized upon to cover up the ugliness of the hastily-built-up barricade. Boulders and Heaths, however, took to each other kindly, in spite of a soil by no means specially suitable, and with the addition, later, of a few good kinds of Cistus and other shrubs, the bank still remains as happy a bit of rough planting as could be desired.