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.
Of the 160 species known only a few are of commercial value. Some of the best known are Androscemum, the Common British Tutsan or Sweet Amber, 1-2 ft. high, remarkable for the scent of its dried leaves; calycinum, commonly called the Rose of Sharon, an almost evergreen species, about 1 ft. high, and flowers 3 in. across; Moserianwm, a hybrid between calycinum and patulum, and having a pretty variety called tricolor, the leaves of which are blotched with green, white, and rosy carmine; rather tender; Hoolcerianum (oblongifolium), from Nepal, is an evergreen, 2-4 ft. high; patulum, a rather tender Japanese plant, 6 ft. high; perforatum, British St. John's Wort; and uralum from Nepal, 2 ft. - all with glossy yellow flowers and numerous conspicuous stamens. Most of them grow in any soil, and are useful for furnishing banks, beneath trees, etc Propagation by cuttings and seeds.