Article from Bean's Trees and Shrubs Hardy in the British Isles
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'Hibiscus syriacus' from the website Trees and Shrubs Online (treesandshrubsonline.
A deciduous shrub, with rather erect branches but bushy habit, up to 10 ft and more high. Leaves variable in size, ordinarily from 2 to 4 in. long, of ovate outline, more or less distinctly three-lobed and coarsely toothed, glabrous except for an occasional bristle on the veins, stalk 1⁄4 to 1 in. long. Flowers produced singly on short stalks from the leaf-axils towards the end of the branch. Each flower is from 21⁄2 to 4 in. across, with five free petals forming a trumpet mouth. The colour is exceedingly variable in the numerous forms of this shrub, some being white, others red, violet, purple, or striped; others again have double or semi-double flowers. Calyx unequally five-lobed, with an involucre of linear bractlets scarcely 1⁄12 in. wide and shorter than the calyx.
The date of the introduction of this shrub to Britain is not known, but as it was included by Gerard among the garden shrubs of his time, it has been cultivated here for probably 350 years. In early times it was known as the ‘Syrian Ketmie’, and in the specific name Linnaeus suggested that it was from Syria, but it has never been found truly wild except in India and China. In Syria, as in more western countries, it exists as a cultivated plant only. It is perfectly hardy in most parts of Britain, but owing to its late-flowering habit, it is often necessary in the north to treat it as a wall plant in order that its flowers may develop under more favourable conditions. In the south, where the cold rains do not come so early, it can be grown quite in the open, and there is no shrub more beautiful during September, especially if that month be hot and sunny. In selecting a place for it, shady and ill-drained spots should be avoided. Any soil of moderate or good quality suits it. It can be propagated by cuttings or by layers, and rare sorts may be grafted on common ones. Plants growing too large for their places may be pruned back in early April. One of the common features of the gardens at Versailles are large bushes of this hibiscus, cut hard back annually into formal shape. Both in France and in Italy it flowers with greater profusion and regularity than under our uncertain skies. A great number of varieties have been raised and named, and the following list must only be regarded as a selection of a representative few of approved merit. On the whole, single-flowered ones are to be preferred.
Flowers Single
Flowers large, opening widely, rich mauvish blue with a deeper centre. A.M. 1965. Raised in France and originally named ‘Oiseau Bleu’.
Flowers white, blush-tinted, with conspicuous bronzy markings in the throat. A.M. 1935. Not to be confused with the species H. hamabo Sieb. & Zucc. Raised in Japan.
Flowers pure white.