This section is from the book "Handbook Of Hardy Trees, Shrubs, And Herbaceous Plants", by W. Botting Hemsley. Also available from Amazon: Handbook of hardy trees, shrubs, and herbaceous plants.
Small deciduous shrubs with opposite oranches and minute stellate often rough hairs. Leaves ovate or lanceolate, serrulate. Flowers scentless, white or pink, solitary, racemose or corymbose, axillary or terminal. Petals 5, induplicate or imbricate. Stamens 10, epigynous; filaments often dilated, and furnished with a lobe at the apex on each side of the anther. Fruit capsular, small, globose, 3- to 5-celled, many-seeded. About half a dozen species are known, nearly all of which are or have been in cultivation. The name is commemorative of one of Thunberg's assistants in Japan.
1. D. gracilis (fig. 98). - This is the smallest species, and at the same time the prettiest in cultivation, the habit being less straggling than in the other species. It grows from 1 to 2 feet high, with numerous slender stems and smooth leaves and small numerous white flowers. It is quite hardy in the south, though a very severe season will destroy the beauty of the blossom; but for early forcing it is almost without a rival. A native of Japan.
D. crenata, syn. D. scabra of gardens. A very handsome erect shrub with slender stems from 4 to 8 feet high. Leaves ovate-lanceolate, rigidly serrulate, rough to the touch. Flowers racemose or paniculate. The single-flowered white variety is usually known by the latter name, and the double varieties by the former, as crendta fibre pleno, and purpurea plena. The first of these two varieties has pink and white flowers, and is already widely grown; but the second is of quite recent acquisition. Japan. The true D. scabra does not appear to be in cultivation. D. Fortunei appears to be a form of the foregoing, that is if we have seen the right plant. The Himalayan species corymbosa and staminea have almost disappeared from our gardens. They are both very showy species, with cymose or corymbose white flowers and foliage similar to crenat]a.
Decumaria, sarmentosa is an allied American plant of climbing habit with small white odoriferous flowers having 7 to 10 petals, numerous stamens, subulate filaments, and only one style. Platycrater Steboldii, syn. P. arguta, is a recently introduced Japanese shrub with lanceolate dentate deciduous leaves and white Philadelphus-like flowers, remarkable for the 4-valvate petals and 2 slender styles.
Fig. 98. Deutzia gracilis. (1/4 nat. size.)