No family of hardy shrubs is more bewildering in the multiplicity and intricacy of its nomenclature than Rosa. Although there are many species now accepted by botanists, yet the pseudo-specific names may be counted by hundreds. Fortunately for those interested in their cultivation, a good many of these names refer to plants with very unimportant distinctions (many of them, indeed, are minor forms of our native Dog Rose), and the best of the wild species are mostly grown under the names applied to them in the following notes.
Their cultivation is simple. They are like the Hybrid Perpetuals in their love for a rich loamy soil—one inclining to a clayey rather than to a sandy nature. Loving abundant sunlight, they are not happy in shady spots. The commonest mistake in their cultivation is in pruning. The notion that they have to be cut back like Hybrid Perpetuals and such-like Roses has often resulted in the loss of a season's flowers, besides destroying for the time the peculiar beauty of habit that many species possess. The shoots, often long, sucker-like growths that push from the base in summer, supply the flowers of the following year, and until they have flowered should not be touched with a knife. Whatever pruning is necessary—and it is, as a rule, a mere matter of thinning out of old worn-out stems—is to give the young growths more air and freedom. No shortening back is needed. It may always be remembered that some of the most beautiful specimens of Wild Roses in existence, especially those of rambling growth, have never been pruned at all. The chief thing is always to retain the free, unfettered grace natural to the plants. Pruning will help to do this, but it must be pruning of the proper kind.
In the wilder parts of the garden the common Dog Rose (R. canina) and its numerous varieties are worth a place; they flower well, and are always beautiful in fruit. The same may be said of the Sweet Briar (R. rubiginosa), the fragrance of whose young growths is always a delight, whether in garden or hedgerow. R. hibernica, a British Rose, thought to be a hybrid between the Scotch Rose and R. canina, comes in the same category. It flowers earlier than the Dog Rose.
For the wild garden also there are several other Roses that may be mentioned, such as cinnamomea, with rosy-red flowers and crimson fruit; nutkana, acicularis, pisocarpa, and californica. Only those are mentioned that from their greater beauty and distinctness deserve a more detailed notice.
R. alba.—Although found wild in several parts of Europe, this, the "Common White Rose" of Linnæus, is supposed to be a hybrid between R. gallica and the Dog Rose. It is always found in places which lead to the belief that it is not truly indigenous, but an escape from cultivated grounds. The typical plant has white flowers that are considerably larger than those of the Dog Rose, and the petals have more substance. There are now numerous double-flowered varieties in gardens, some beautifully tinged with rose.
R. Alberti.—A native of Turkestan, where it was discovered by M. Albert Regel not many years ago. This is one of the rarest species of Rosa in cultivation. The flowers are bright yellow, the leaves small and much divided.
R. alpina.—This is the species from which the Boursault Roses have been derived. It is a native of the Alps and Pyrenees. The stems are 4 to 5 feet high, and have few or no spines except when young. The flowers are rosy red; the fruits red, often pear-shaped, and covered with bristles, which, when rubbed, have a turpentine-like odour.
R. arvensis (or R. repens).—From this species the Ayrshire Roses have been obtained. It is naturally a trailing or climbing plant, having long thin shoots and white flowers. When trained over tree stumps or rough stakes and ultimately allowed to grow at will, it forms tangled masses which are very pretty. But the double forms—even the common variety, flore-pleno—are to be preferred, being especially useful in semi-wild spots. The type is wild in England, and frequently to be seen in hedges and thickets.
R. carolina.—For certain positions this is a useful Rose. It has erect stems and forms dense thickets, spreading rapidly by means of the numerous underground rhizomes it sends out in all directions. The flowers are purplish-rose. A later-flowering variety known as nuttalliana is a stronger grower and has larger flowers. This will flower up to September. R. lucida and R. nitida are, like R. carolina, natives of North America, and are of similar habit, but they are dwarfer and the leaves are more glossy. All these are apt to become crowded with old stems, and, besides an occasional thinning out, are much improved by dividing up every three or four years.
R. ferruginea (R. rubrifolia).—This species, which comes from the Pyrenees and Alps, is remarkable for the reddish-purple colour of its leaves and young shoots. Groups of half-a-dozen or more plants give a striking colour effect. The flowers are similar to the Dog Rose, but red.