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.
This is one of a large and very varied genus, consisting of evergreen and deciduous trees and shrubs, along with a considerable number of herbaceous plants and annuals. The various species are found distributed over the tropical and temperate regions of both the old and new worlds. All the sorts have handsome foliage and showy flowers, and some, such as the grand H. roseus sinensis with its fine varieties, with single and double flowers, are among the most valued ornaments of our stoves and greenhouses. With the exception, however, of the one which forms the subject of this paper, the ligneous species are too tender for our climate in the open air. As its specific name implies, it is indigenous to Syria, but it is also found more or less abundantly in several of the surrounding countries, growing in high mountain valleys, and forming an amply branched bush with a somewhat upright habit of growth, of from 8 to 10 feet in height. It was formerly associated with the Hollyhocks and Mallows in the genus Althcea, and is still known under the name of Althtea frutex or "Shrubby Hollyhock." It has been cultivated in British gardens since 1596. The leaves are of a light-green tint, ovate in outline, serrated, and distinctly three-lobed. The pretty bell-shaped purple flowers are borne on long footstalks from the sides of the young branches, and begin to expand early in September.
The Syrian Hibiscus, though now little known, and comparatively seldom met with, is one of the finest of our hardy deciduous flowering shrubs, of free growth in any rich deep soil, and hardy enough for the open shrubbery border. It is found, however, to flower best when enjoying the protection of a sunny wall, a position for which it is well adapted, notwithstanding the absence of foliage in winter, a defect to some extent compensated for by its rich autumnal beauty, while its smooth whitish bark forms quite a feature after the decay of the leaves.
It is found to grow well in the smoke and dust of towns, and might with advantage be introduced into our squares and parks much more extensively than it has been hitherto.
Of a large number of varieties, the following are the most attractive: they are all equally hardy with the parent, and in some cases more beautiful, so far as flowers are concerned.
Var. alba - flowers pure white.
,, ardens - bright violet.
,, azurea plena - double blue.
,, caerulea plena - double dark blue.
Var. elegantissima - blue and purple.
,, fastuosa - bright rose.
,, grandiflora - large red.
,, purpurea variegata - purple, with silvery variegated leaves.
,, purpurea plena - double reddish purple.
,, speciosa plena - double white, purple striped.
,, violacea plena - double violet.