This section is from the book "The Gardener V1", by William Thomson. Also available from Amazon: The New Organic Grower: A Master's Manual of Tools and Techniques for the Home and Market Gardener.
Of the long list of species which compose this genus of beautiful flowering evergreen shrubs, comparatively few have been found sufficiently hardy for open-air cultivation in Britain, and even these require the shelter of a wall to enable them to survive the rigours of our ordinary winters. The great bulk of the sorts are indigenous to the south of Europe, where they are widely distributed; but a few are found in Northern Asia, and on the African shores of the Mediterranean. Most of the species are of free growth in ordinary soils, preferring such as are light and well drained. They are all more or less remarkable for the fugaciousness of their flowers, the corollas in most cases expanding in the morning and falling off at sunset. As others, however, come on in rapid succession and in great abundance, the plants maintain their gay appearance for five or six weeks in summer. This peculiarity is thus prettily alluded to by one of the poets, who says -
"Yet though the gauzy hells fall fast,
Long ere appears the evening crescent, Another bloom succeeds the last, As lovely and as evanescent".
A resinous gum, which exudes from the leaves and young branches of most of the species, notably from those of C. ladaniferus, and known in commerce by the name of "labdanum," has a pleasant aromatic fragrance, and is used medicinally in a variety of ways, particularly in plasters, and by perfumers in the preparation of cosmetics. This substance is said to have formerly been gathered from the beards of the "goats, whereon it collected while they browsed on the plants".
It is now, however, collected by a leather comb drawn over the branches, to the teeth of which the juice readily adheres, forming an ever-thickening crust, and is easily scraped off with a knife.
This is an evergreen shrub of about 5 feet in height, indigenous to Spain and Portugal in mountainous districts. It has been cultivated in our gardens since 1629. The leaves are oblong-lanceolate, smooth, dark-green on the upper surface, and slightly hoary below. The flowers are white, with a dark-brownish or crimson spot at the base of each petal, appearing in wonderful profusion in June and July. This is one of the most valuable of our wall shrubs, hardy, and of robust growth in any situation where the soil is dry and moderately rich, and, like all its congeners, remarkably patient under the pruning-knife. As it flowers, however, from the shoots of the previous year, care should always be taken to thin the branches, rather than indiscriminately cutting off all the young wood. The so-called species, "Cyprius," or Island of Cyprus Cistus, differs only from this in its flowers being destitute of the beautiful blotch so attractive in those of the Gum Cistus, and is probably only a variety: it is interesting, however, as a companion plant in collections of wall shrubs.
A robust evergreen shrub, found naturally over a wide area in Spain and the south of France, where it grows to the height of about 6 feet. It was introduced to our gardens in 1771. The leaves are large, of an ovate-lanceolate form, thick and leathery in texture, smooth dark-green above, and covered on the under surface with a minute down. The flowers, which appear in July and August, are pure white, clothed with prominent red bracts, which are very ornamental just before the flowers expand. This is a very free-growing species, one of the hardiest in cultivation, and very desirable for covering walls. It stands, however, in many districts as a specimen shrub in the open border, when planted in light, well-drained soil.
This is a species introduced from the Levant so early as 1659. It is a sub-evergreen, with an erect bushy habit of growth, from 3 to 4 feet in height. The leaves are oblong-lanceolate, prominently veined, undulated at the margins, and of a dark-green colour. The flowers, which are produced in June and July in great abundance, are reddish-purple, with a bright-yellow spot at the base of each petal. The petals are imbricated and crumpled. The young branches are covered with a minute pubescence. Though somewhat tender, even on a sheltered wall, this species deserves a trial in any favourable situation, the abundance and brilliancy of its flowers, and its neat distinct foliage, rendering it quite a feature in a collection of dwarf wall-plants. A dry, well-drained soil is essential to its wellbeing, and a slight covering during the severest of the winter will in most cases save it from damage.
A distinct-looking dwarf evergreen, seldom exceeding 3 feet in height. Found wild over a large area in Spain and the south of France, especially on the mountains of Corbieres, from whence it is reported as having been sent to this country in 1656. The leaves are of an ovate form, distinctly acuminate, wrinkled on both sides; the margins fringed, of a deep-green colour, and very glutinous. The flowers appear in May and June, generally in remarkable profusion. They are pure white, the margins of the petals tinged with delicate rose. This is one of the hardiest, as well as the most ornamental, of the genus. It is of very free growth, and well worthy of a prominent place among neat, dwarf, wall evergreens. Hugh Fraser.