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.
1. C. stylosa. - A very pretty plant in an otherwise uninteresting genus. A dwarf tufted perennial with slender straggling stems and whorls of linear acute hispid leaves. Flowers rosy pink, in terminal compact cymes, produced all the Summer. The style is conspicuously exserted beyond the corolla, hence the specific name. Persia.
Houstdnia cairulea, a North American plant of similar appearance, but belonging to another tribe, with opposite leaves and a several-seeded capsule, has lilac-blue flowers, and being of very diminutive growth is well adapted for rock-work. Mitchella repens is another North American plant, of creeping habit, having oval persistent leaves, white flowers, and red berries. Some other species of the Cinchonaceae are occasionally seen in the border, but none are perfectly hardy. Bouvardia triphylla is one of the best suited for this purpose.