This section is from "The Horticulturist, And Journal Of Rural Art And Rural Taste", by P. Barry, A. J. Downing, J. Jay Smith, Peter B. Mead, F. W. Woodward, Henry T. Williams. Also available from Amazon: Horticulturist and Journal of Rural Art and Rural Taste.
All the species of this beautiful genus are tained by some French cultivators, by whom it was soon extensively distributed. The plants produced at first only small and few flowers, in consequence of its proper treatment being imperfectly known. But when subsequently they were grown in a peaty soil, and freely supplied with water in the period of their vegetation, they soon assumed a very different appearance, and their real beauty was discovered. This fact alone might teach us to abstain from pronouncing a decided opinion on the merits of a newly introduced plant before the proper method of treating it has been proved by experiment . Many species of the same genus have since then been introduced, but these are not so beautiful as the old one. Their umbels are smaller, and the blossoms are less highly colored; moreover, with the newer sorts, the large unfertile flowers are less numerous than in the old species, the umbels of which are almost compact. This monstrosity is apparently the result of long experimental culture in the Chinese and Japanese gardens, and it is scarcely to be doubted that ultimately the smaller flowers will be made to bloom as large and as profusely as the others. The beautiful species which has called forth these observations, would seem to confirm this supposition.
Its unfertile exterior flowers are double, of a bright rose color. According to Siebold, who, however, does not appear to have introduced living plants of it, it grows on the highest mountains of the island of Niphon and Sikok, (Japan,) where it flowers during the months of July and August. It is grown plentifully in the gardens of these parts, and forms a handsome plant, with a stem about three feet high. According to some travellers, there are four varieties of it; one lilac, the others with flesh-colored, yellowish, and rose-colored flowers. The leaves are opposite, rounded at the base, or nearly heart-shapea.- Van Houtte's Floret des Serres.