This section is from the book "Commercial Gardening Vol4", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
The most popular species is D. florida, formerly better known as Weigela rosea. It is a deciduous Chinese shrub, 6-8 ft. high, with masses of tubular rose or white flowers in April and May. There are several varieties, including amabilis or grandiflora, of which there are also many forms, such as Isolina, striata, Van Houttei, Stelzneri, etc. Other species are canadensis and sessilifolia, both with yellow flowers; and Middendorfiana, yellowish white dotted with pink. There are now several hybrid forms, of which the crimson-red Eva Bathke and the red-purple Abel Carriere are the best. These plants are easily raised from cuttings, layers, or suckers, and also from seeds, and flourish in any good garden soil.