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.
Dwarf, trailing, or erect shrubs with opposite or alternate simple usually entire leaves with large or small or no stipules and solitary or racemose showy ephemeral flowers. Flowers regular. Sepals 3 to 5, imbricate, the two outer usually smaller or absent. Petals 5, scarcely clawed, imbricate, spreading, very thin and fugacious. Stamens many, hypogynous; filaments free, filiform. Capsule 1-celled, or several-celled in consequence of the projecting parietal placentas; seeds numerous, albuminous, orthotropous. Chiefly from the Mediterranean region; a few dispersed throughout Europe, and a few found in North and South America, and Central and Eastern Asia.